Coffee Science Alert n° 10
June 2007
AGRONOMY
Survey of Vietnamese coffee beans for the presence of ochratoxigenic Aspergilli
Ilic, Z.; Bui, T.; Tran-Dinh, N.; Dang, M. H.; Kennedy, I.; Carter, D.
Vietnamese coffee beans were investigated for the presence of ochratoxigenic Aspergilli. Ninety-three percent of the coffee samples studied were positive for A. niger. No other ochratoxigenic species were present. HPLC analysis determined that 8.7% of the A. niger strains were positive for ochratoxin A (OA) production. There was no significant difference in the level of contamination or incidence of toxigenic strains in samples that had been rejected by manual sorting and those that were destined for human consumption. No OA-producing fungi were uncovered in a fresh coffee bean sample analysed, suggesting that the OA problem most likely occurs post-harvest.
Source : Mycopathologia 2007 vol.163 Issue 3 pp 177 - 182
Residuos de tiametoxam, aldicarbe e de seus metabolitos em folhas de cafeeiro e efeito no controle de Leucoptera coffeella (Guerin-Meneville) (Lepidoptera: Lyonetiidae). [Residues of thiamethoxam, aldicarb and its metabolites in coffee leaves and effect on the control of Leucoptera coffeella (Guerin-Meneville) (Lepidoptera: Lyonetiidae)]
iez-Rodriguez, G. I.; de Baptista, G. C.; Trevizani, L. R.; Haddad, M. L.; Nava, D. E.
The coffee leaf miner Leucoptera coffeella (Guerin-Meneville), one of the major pests of coffee crops in Brazil, is mainly controlled with insecticides. The objective of this study was to evaluate the residues and the translocation of the insecticide thiamethoxam in coffee leaves, as well as to study its effect on the coffee leaf miner control, comparing it with aldicarb, used as standard. One experiment was set up in the county of Garca, SP from December/2001 to August/2002. The treatments used were: aldicarb 150 G at the rates of 2.25 and 4.50 g a.i./pit, thiamethoxam 10 GR, at the rates of 0.15 and 0.30 g a.i./pit and check. Twig samples were collected prior to and 30 , 60, 90, 120, 150, 180, 210 and 240 days after the application, at three coffee plant heights (lower, middle and upper third), and the percentage of mined leaves was evaluated. The determination of aldicarb residues, including their sulphoxide and sulfone metabolites and of thiamethoxam were performed by gas chromatography with a nitrogen-phosphorus and mass spectrometer detectors, respectively. The results indicated a uniform translocation of both insecticides in all three thirds of the coffee plants when applied to the soil. A higher persistence of thiamethoxam was verified with its residues being found for as far long as eight months following the application, while aldicarb residues, including the sulphoxide and sulfone metabolites, were found only until four to six months after the application. Control of the coffee leaf miner was observed with both insecticides.
Suorce : Neotrop.Entomol 2006 vol.35 (2), pp 257 - 263
Characterisation of a Malawian isolate of Beauveria bassiana, a potential control agent of coffee stem borer, Monochamus leuconotus
Kutywayo, V.; Karanja, L.; Oduor, G.; Nyirenda, S.
The radial growth, sporulation and viability of a Beauveria bassiana isolate were assessed at three temperatures (23, 28, 33 degrees C) under light and dark conditions. Optimum radial growth and sporulation occurred at 23 degrees C regardless of photoperiod with the highest spore concentration being attained after incubating for 28 days. Loss of viability was highest at 33 degrees C and there was no significant loss in viability at 23 degrees C for up to five weeks. It would appear that 33 degrees C is too hot for the sporulation, growth and viability of this insect fungus. Photoperiod effects were insignificant for all the parameters evaluated. The infectivity on white coffee stem borers at 2.5 x 10(8) spores ml(-1) was high with 100% of the test larvae immobilised and not feeding within 24 h and dying within two to twelve days.
Source : Commun Agric Appl Biol Sci 2006 vol.71 (2 Pt A?, pp 245 - 252 (not available on -line)
BIOCHEMISTRY / BIOTECHNOLOGY
A preliminary study of caffeine degradation by Pseudomonas sp. GSC 1182
Gokulakrishnan, S.; Chandraraj, K.; Gummadi, S. N.
Several microorganisms isolated from soil were tested for their ability to utilize caffeine as the sole carbon and nitrogen source. The isolate identified as Pseudomonas sp. GSC 1182 showed 80% degradation of caffeine in 48 h when caffeine was used as the sole carbon and nitrogen source. In the presence of sucrose (5 g/l), 100% degradation of caffeine was achieved within 36-40 h. The degradation rate was also found to increase when fructose, lactose and galactose were used as carbon source. The isolate showed decreased level (<10%) of caffeine degradation in the presence of glucose. At an initial pH of 6.0, the complete degradation of caffeine was attained in 24 h. The addition of urea and ammonium sulfate as external nitrogen source decreased the caffeine degradation to 35% and 70% respectively.
Source : Int J Food Microbiol 2007 vol.113 (3), pp 346 - 350
Cloning, expression, crystallization and preliminary X-ray analysis of the XMT and DXMT Nmethyltransferases
McCarthy, A. A.; Biget, L.; Lin, C.; Petiard, V.; Tanksley, S. D.; McCarthy, J. G.
Caffeine is a secondary metabolite produced by a variety of plants including Coffea canephora (robusta) and there is growing evidence that caffeine is part of a chemical defence strategy protecting young leaves and seeds from potential predators. The genes encoding XMT and DXMT, the enzymes from Coffea canephora (robusta) that catalyse the three independent N-methyl transfer reactions in the caffeinebiosynthesis pathway, have been cloned and the proteins have been expressed in Escherichia coli. Both proteins have been crystallized in the presence of the demethylated cofactor S-adenosyl-L-cysteine (SAH) and substrate (xanthosine for XMT and theobromine for DXMT). The crystals are orthorhombic, with space group P2(1)2(1)2(1) for XMT and C222(1) for DXMT. X-ray diffraction to 2.8 A for XMT and to 2.5 A for DXMT have been collected on beamline ID23-1 at the ESRF.
Source : Acta Crystallograph.Sect.F Struct Biol Cryst.Commun 2007 vol.63 (Pt4), pp 304 - 307
Secondary metabolites in fruits, vegetables, beverages and other plant-based dietary components
Crozier, A.; Yokota, T.; Jaganath, I. B.; Marks, S.; Saltmarsh, M.; Clifford, M. N.
The following topics are considered in this chapter: dietary phytochemicals; vegetables, including root crops, onions and garlic, cabbage family and greens, legumes, lettuce, celery, asparagus, avocados, artichoke, tomato and related plants and squashes; fruits, including apples and pears, apricots, nectarines and peaches, cherries, plums, citrus fruits, pineapple, dates, mango, papaya, fig, olive, soft fruits, melons, grapes, rhubarb, kiwi fruit, bananas and plantains and pomegranate; herbs and spices; cereals; nuts; algae; beverages, including tea, mate, coffee, cocoa, wines, beer, cider and scotch whisky; and databases.
PROCESSING
Influence of coffee/water ratio on the final quality of espresso coffee
Andueza, S.; Vila, M. A.; Paz, de Pena; Cid, C.
A number of factors influence the physicochemical and sensory properties of espresso coffee, including selection of ground roasted coffee and the percolation conditions. The coffee/water ratio is another influential factor, although few studies have examined this. The present study, therefore, aimed to evaluate the influence of the coffee/water ratio on the physicochemical and sensory properties of espresso coffee. In addition, the effects of coffee variety, either Arabica or Robusta, and the type of roast, either conventional or torrefacto, on the selection of the water/coffee ratio were also examined. The results indicated that type of roast seemed to have the greatest influence on the selection of the optimum coffee/water ratio. The addition of sugar during roasting in the torrefacto roasting process led to the generation of more acidic compounds and melanoidins than were formed in the conventional roasting process. Thus, for torrefacto roasted coffees, a lower coffee/water ratio was preferred than for conventionally roasted coffees.
Source : J Sci Food Agric 2007 vol. 87 (4), pp 586-592
Roasting technology gets more flexible and fuel efficient
Anon.
Interest in speciality coffees has increased, with roasting equipment needing to be highly flexible to meet taste and blend changes. The Therma Two multi-function roaster from Probat combines the roasting systems of three different roaster types and includes a special fresh air supply for roasting very dark roasts. Technical solutions are needed to reduce the energy required for roasting, as well as new treatments for emissions produced by the coffee roasting process. Recirculation of exhaust gases, green coffee preheating and Probat's Proforte process using flameless, regenerative thermal exhaust combustion technology are detailed as potential solutions. Green coffee is preheated in a way that enables energy to be reused. Widespread take-up of speciality coffee by coffee shops and cafes has introduced a new class of coffee drinkers in an international market. Control of roast profile consistency, and control and reduction of fuel cost and environmental impact are outlined. The Opus 3G roaster has gained market share.
Source : Coffee Cocoa Intern 2007 vol. 33 (6), pp 27-29 (not available on-line)
Mathematical modeling of caffeine kinetic during solid-liquid extraction of coffee beans
Espinoza-Perez, J. D.; Vargas, A.; Robles-Olvera, V. J.; Rodriguez-Jimenes, G. C.; Garcia-Alvarado, M. A.
Rigorous and simplified models were proposed for caffeine kinetic description during the solid-liquid extraction process of coffee decaffeination. The evolution of caffeine concentration was measured both in extract and refined phases by gas chromatograph. The rigorous model is a non-steady diffusion equation for the coffee beans couple with macroscopic mass transfer equation for solvent. The simplified one is the analytical solution of macroscopic mass transfer equations for beans and solvent. In both models, rectangular coordinates were assumed. Caffeine internal mass diffusivity was estimated by fitting the simplified model to experimental results. The caffeine diffusivity in coffee beans yields 3.209x10-10m2s-1 at 90°C. The simplified model reproduce adequately the experimental kinetic of caffeine in both phases.
Source : J Food Eng 2007 vol.81 (1), pp 72 - 78
Impact of ecological post-harvest processing on the volatile fraction of coffee beans: I. Green coffee
Gonzalez-Rios, O.; Suarez-Quiroz, M. L.; Boulanger, R.; Barel, M.; Guyot, B.; Guiraud, J. P.; Schorr-
Galindo, S.
Green coffees produced by three variants of the wet process and a new 'ecological' process were characterised for their aroma using combined headspace solid-phase microextraction/gas chromatography-mass spectroscopy (HS-SPME/GC-MS) and headspace solid-phase microextraction/gas chromatography-olfactometry (HS-SPME/GC-O). The effect of each post-harvest processing operation on the volatile fraction of the coffee produced was studied, particularly the effect of reducing the amount of water used in the process. The comparison of the green coffees from the different treatments revealed the importance of mucilage removal in distinguishing between the samples, and showed the merits of microbial mucilage removal in water to obtain coffees with a better aroma quality. These latter coffees were in fact characterised by pleasant and fruity aromatic notes, whereas those obtained after mechanical mucilage removal used in the ecological process were characterised by volatile compounds with an unpleasant note.
Source : J Food Compos Anal 2007 vol.20(3-4), pp 289-296
Impact of ecological post-harvest processing on coffee aroma: II. Roasted coffee
Gonzalez-Rios, O.; Suarez-Quiroz, M. L.; Boulanger, R.; Barel, M.; Guyot, B.; Guiraud, J. P.; Schorr-
Galindo, S.
The purpose of this study was to determine how water and microbial stages in post-harvest processing affect the volatile content of coffee. Following our aroma analysis carried out on green coffees, we turned our attention to roasted coffees. Coffees produced by three variants of the wet method, and by an ecological process, were compared after roasting. Three degrees of roasting were applied to gain a clearer picture of the differences in roasted coffee aromas by means of a volatile compound analysis. Changes in the post-harvest process actually led to aroma differences in roasted coffees, and with light roasting it was possible to more effectively distinguish between the four treatments based on aroma criteria. Coffee produced by the traditional wet method, with microbial stages, had a better aroma quality than coffee produced by the ecological method, which was purely mechanical. Moreover, in the microbial method, mucilage removal under water gave coffees with more fruity, floral and caramel notes, whereas dry mucilage removal gave more neutral coffees. These results confirmed the importance of microbial mucilage removal under water and tallied with the results of our previous study on green coffee. This work provides coffee producers and roasters with an insight into the volatile composition of roasted coffee depending on the post-harvest process used and degree of roasting applied.
Source : J Food Compos Anal.2007 vol.20 (3-4, pp 297 - 307
Fermentation quality and nutritive value of a total mixed ration silage containing coffee grounds at ten or twenty percent of dry matter
Xu, C. C.; Cai, Y.; Zhang, J. G.; Ogawa, M.
Six wethers were used in a replicated 3 x 3 Latin square to study the fermentation quality and nutritive value of total mixed ration (TMR) silages that included wet coffee grounds (WCG). The TMR were prepared using a commercial compound feed, timothy hay, alfalfa hay, dried beet pulp, and a vitaminmineral supplement in a ratio of 36.5:30:20:12:1.5, respectively, on a DM basis, with timothy hay and alfalfa hay being replaced by WCG at 0, 10, or 20%. All TMR silages, irrespective of WCG addition, were well preserved, with a low pH and ammonia-N content and a high lactic acid content. Intakes by wethers of TMR silages containing 0 and 10% WCG were 96.6 and 94.8 g/kg of BW(0.75), and did not differ (P > 0.05). Intake of TMR silage containing 20% WCG was 76.8 g/kg of BW(0.75), which was equal to 80% of that of the TMR silage with no WCG (quadratic: P < 0.01). Increasing concentrations of WCG in the rations decreased the digestibility of DM, CP, ADF, NDF, and energy, and increased that of ether extract (P < 0.05). The TDN and DE contents of the TMR silages with 0 and 10% WCG were similar, but the TMR silage with 20% WCG was lower (P < 0.05). With progressive increases in WCG concentrations, N intake did not differ, but fecal and urinary N increased linearly (P < 0.001), and retained N decreased linearly (P < 0.001). This study demonstrated that the proportion of WCG to be incorporated into TMR silages should not exceed 10% of the DM.
Source : J Anim Sci 2007 vol.85 (4), pp 1024 - 1029
Verwaarloosbare hoeveelheden cholesterolverhogende diterpenen in koffie gezet met de koffiepadzetmethode bij vergelijking met ongefilterde kookkoffie. [Negligible amounts of cholesterolraising diterpenes in coffee made with coffee pads in comparison with unfiltered coffee]
Boekschoten, M. V.; van Cruchten, S. T.; Katan, M. B.; Kosmeijer-Schuil, T. G.
To determine the amounts of the serum-cholesterol raising diterpenes cafestol and kahweol in coffee made with coffee pads and the Senseo coffee machine as opposed to filtered and unfiltered coffee. DESIGN: Observational. METHOD: In five cities in the Netherlands coffee was purchased in three major supermarkets resulting in a total of 30 samples of coffee pads. The levels of cafestol and kahweol were determined by gas chromatography. As controls, the diterpene levels in filtered and unfiltered coffee were also measured. RESULTS: Coffee prepared using coffee pads contained on average 0.76 mg/l cafestol (95% CI: 0.69-0.82) and 0.85 mg/l kahweol (95% CI: 0.77-0.94). Filtered coffee contained 0.76 mg/l cafestol (95% CI: 0.63-0.88) and 0.81 mg/l kahweol (95% CI: 0.63-0.99). Unfiltered coffee contained 72.5 mg/l cafestol (95% CI: 48.5-96.4) and 71.5 mg/l kahweol (95% CI: 45.0-98.1).
CONCLUSION: Coffee prepared using coffee pads and the Senseo coffee machine contained minute levels of diterpenes comparable to those of filtered coffee. Its effect on serum-cholesterol levels is therefore likely to be negligible.
Source : Ned Tijdschr Geneeskd. 2006 vol.150 Issue 52 pp 2873 - 2875
CHEMISTRY / SENSORICS
Structure determination and sensory analysis of bitter-tasting 4-vinylcatechol oligomers and their
Frank, O.; Blumberg, S.; Kunert, C.; Zehentbauer, G.; Hofmann, T.
Aimed at elucidating intense bitter-tasting molecules in coffee, various bean ingredients were thermally treated in model experiments and evaluated for their potential to produce bitter compounds. As caffeic acid was found to generate intense bitterness reminiscent of the bitter taste of a strongly roasted espresso-type coffee, the reaction products formed were screened for bitter compounds by means of taste dilution analysis, and the most bitter tastants were isolated and purified. LC-MS/MS as well as 1-D/2-D NMR experiments enabled the identification of 10 bitter compounds with rather low recognition threshold concentrations ranging between 23 and 178 micromol/L. These bitter compounds are the previously unreported 1,3-bis(3',4'-dihydroxyphenyl) butane, trans-1,3-bis(3',4'-dihydroxyphenyl)-1-butene, and eight multiply hydroxylated phenylindanes, among which five derivatives are reported for the first time. In addition, the occurrence of each of these bitter compounds in a coffee brew was verified by means of LC-MS/MS (ESI-) operating in the multiple reaction monitoring (MRM) mode. The structures of these bitter compounds show strong evidence that they are generated by oligomerization of 4-vinylcatechol released from caffeic acid moieties upon roasting.
Source : J Agric Food Chem 2007 vol.55 (5), pp 1945 - 1954
Comparison of bean biochemical composition and beverage quality of Arabica hybrids involving Sudanese-Ethiopian origins with traditional varieties at various elevations in Central America
Bertrand, B.; Vaast, P.; Alpizar, E.; Etienne, H.; Davrieux, F.; Charmetant, P.
For buyers of Arabica coffee (Coffea arabica L.) in Central America, elevation and variety are important indicators of quality. We compared coffee produced by three types of varieties established in various trials at elevations ranging from 700-1600 m in three countries (El Salvador, Costa Rica and Honduras). Arabica hybrids resulting from crosses of Sudanese-Ethiopian origins with either traditional varieties or with introgressed lines derived from the hybrid of Timor (C. arabica x Coffea canephora Pierre ex Froehn) were compared with traditional cultivars (TC). Effects of elevation and variety on bean biochemical composition (caffeine, chlorogenic acid, trigonelline, fat and sucrose) were evaluated by predictive models based on calibration of near-infrared (NIR) spectra and by chemometric analysis of the global NIR spectrum. Beverage quality tests were performed by a panel of ten professional cup-tasters. Experiment 1 was carried out on the slopes of the Poas volcano (Costa Rica) with the traditional cultivar 'Caturra'. Experiment 2 compared the three varieties in a network of trials established in three countries of Central America. Significant linear regressions with elevation were observed in Experiment 1 with Caturra and in Experiment 2 for the traditional cultivars, and trends were established relating variation in biochemical compounds and cup quality to elevation. Convergence or divergence of the new hybrids in relation to these trends was observed. For the traditional cultivars, elevation had a significant effect on bean biochemical composition, with chlorogenic acid and fat concentrations increasing with increasing elevation. For the Arabica hybrids, elevation explained little of the variation in chlorogenic acid concentration and none of the variation in fat concentration. Nevertheless, Arabica hybrids had 10-20% higher fat concentrations than the traditional varieties at low elevations and similar fat concentrations at high elevations. The samples could be discriminated according to elevation based on NIR spectra; however, the spectra of the TC varieties were more strongly modified by elevation than the spectra of the hybrids. Nonetheless, this analysis confirmed homeostasis of the hybrids for which bean biochemical composition was less affected by elevation than that of the traditional varieties. The organoleptic evaluation, performed on samples originating from high elevations, showed no significant differences between Arabica hybrids and traditional cultivars. The new hybrid varieties with high beverage quality and productivity potential should act as a catalyst in increasing the economic viability of coffee agroforestry systems being developed in Central America.
Source : Tree Physiol 2006 vol.26 Issue 9 pp 1239 - 1248
CHEMISTRY
Determination of beta-carboline alkaloids in foods and beverages by high-performance liquid chromatography with electrochemical detection at a glassy carbon electrode modified with carbon nanotubes
Agui, L.; Pena-Farfal, C.; Yanez-Sedeno, P.; Pingarron, J. M.
A method based on HPLC with amperometric detection was developed for determination of betacarboline alkaloids in foods and beverages. Optimization of sample pre-treatments for specific foods and application of the method to the analysis of beer, coffee and cheese samples contaminated artificially with beta-carbolines are reported. The HPLC employed an Ultrabase C18 column and isocratic elution. The amperometric detection involved use of glassy C electrodes modified with multiwalled C nanotubes which allowed direct detection of the analytes in a mobile phase composed of methanol and acetonitrile in a disodium orthophosphate solution (pH 9.0). Using the method, complete separation of harmalol, harmaline, norharmane, harmane and harmine was achieved. The quantification range of the assay was 4-19 ng/ml. Recoveries of beta-carbolines from beer, coffee and cheese were in the ranges 92-102, 92-101 and 88-100%, respectively.
Source : Anal Chim Acta 2007 vol.585 (2), pp 323 - 330
Determination of acrylamide levels in selected foods in Brazil
Arisseto, A.; Toledo, M.; Govaert, Y.; van Loco, J.; Fraselle, S.; Weverbergh, E.; Degroodt, J.
Acrylamide is a toxin that is formed during normal cooking processes. In this study the authors
determined acrylamide levels in processed foods consumed in Brazil. The highest levels were found in
potato products processed at high temperatures and instant coffee. Products based on cassava and
maize were found to contain the lowest levels. Acrylamide concentrations were found to be between less
than 20 mcg/kg and 2528 mcg/kg.
Source : Food Add Contam 2007 vol. 24 (3), pp 236-241
Factors influencing the norharman and harman contents in espresso coffee
Alves, R. C.; Casal, S.; Oliveira, B. P.
Espresso coffee (EC) brews were analyzed for beta-carboline [norharman (NH) and harman (H)] contents, by RP-HPLC with fluorescence detection. The influence of the coffee species (arabica or robusta), the roast degree, and the brew length was studied. The results show that the content of NH and H in EC is dependent primarily on the coffee species, followed by brew length. The roast degree has only a minor influence on the final content of NH and H in EC. When compared with other coffee brews, EC has an amount of these beta-carbolines (in micrograms per liter) similar to that of mocha coffee, both being more concentrated than filter and press-pot coffees. Therefore, the consumer's preferences will determine the amount of NH and H ingested daily. For the caffeinated 30 mL of EC, the arabica coffees contain about 4.08 microg of NH and 1.54 microg of H. Commercial blends (usually with a maximum of 30% robusta) range from the cited arabica values to 10.37 microg of NH and 4.35 microg of H.
Source : J Agric Food Chem 2007 vol.55 (5), pp 1832 - 1838
New method for caffeine quantification by planar chromatography coupled with electropray ionization
Aranda, M.; Morlock, G.
A new high-performance thin-layer chromatography/electrospray ionization mass spectrometry
(HPTLC/ESI-MS) method for the quantification of caffeine in pharmaceutical and energy drink samples
was developed using stable isotope dilution analysis (SIDA). After sample preparation, samples and
caffeine standard were applied on silica gel 60 F(254) HPTLC plates and over-spotted with caffeine-d(3)
used for correction of the plunger positioning. After chromatography, densitometric detection was
performed by UV absorption at 274 nm. The bands were then eluted by means of a plunger-based
extractor into the ESI interface of a single-quadrupole mass spectrometer. For quantification by MS the
[M+H](+) ions of caffeine and caffeine-d(3) were recorded in the positive ion single ion monitoring (SIM)
mode at m/z 195 and 198, respectively. The calibration showed a linear regression with a determination
coefficient (R(2)) of 0.9998. The repeatability (RSD, n = 6) in matrix was </= +/- 3.75%. The intermediate
precisions (RSD, n = 2) for two samples of different brand names were determined three times and
ranged between RSD +/-0.68% and +/-2.64% (sample 1) and between +/-3.44% and +/-8.60% (sample
2). The method accuracy was evaluated by comparing the results obtained by HPTLC/SIDA-ESI-MS with
those from the validated HPTLC/UV method. The results for pharmaceutical and energy drink samples
were (ng/band) 99.82 +/- 3.75 and 338.09 +/- 4.87 by HPTLC/SIDA-ESI-MS and 104.74 +/- 1.51 and
334.86 +/- 5.63 by HPTLC/UV. According to the F-test (homogeneity of variances) and the t-test
(comparison of means) the two methods show no significant difference. The detection and quantification
limits were 75 and 250 microg L(-1) (0.75 and 2.5 ng/band), respectively, which were a factor of 13 lower
than those established for HPTLC/UV. The positioning error (RSD +/-6%) was calculated by comparing
HPTLC/SIDA-ESI-MS with HPTLC/ESI-MS. However, using SIDA the positioning error was nullified.
HPTLC/SIDA-ESI-MS was demonstrated to be a highly reliable method for the quantification of
compounds by planar chromatography coupled online with mass spectrometry.
Source : Rapid Commun Mass Spectrom 2007 vol.21 Issue 7 pp 1297 - 1303
Development of a biosensor for caffeine
Babu, V. R.; Patra, S.; Karanth, N. G.; Kumar, M. A.; Thakur, M. S.
We have utilized a microbe, which can degrade caffeine to develop an Amperometric biosensor for determination of caffeine in solutions. Whole cells of Pseudomonas alcaligenes MTCC 5264 having the capability to degrade caffeine were immobilized on a cellophane membrane with a molecular weight cut off (MWCO) of 3000-6000 by covalent crosslinking method using glutaraledhyde as the bifunctional crosslinking agent and gelatin as the protein based stabilizing agent (PBSA). The biosensor system was able to detect caffeine in solution over a concentration range of 0.1 to 1 mg mL(-1). With read-times as short as 3 min, this caffeine biosensor acts as a rapid analysis system for caffeine in solutions. Interestingly, successful isolation and immobilization of caffeine degrading bacteria for the analysis of caffeine described here was enabled by a novel selection strategy that incorporated isolation of caffeine degrading bacteria capable of utilizing caffeine as the sole source of carbon and nitrogen from soils and induction of caffeine degrading capacity in bacteria for the development of the biosensor. This biosensor is highly specific for caffeine and response to interfering compounds such as theophylline, theobromine, paraxanthine, other methyl xanthines and sugars was found to be negligible. Although a few biosensing methods for caffeine are reported, they have limitations in application for commercial samples. The development and application of new caffeine detection methods remains an active area of investigation, particularly in food and clinical chemistry. The optimum pH and temperature of measurement were 6.8 and 30+/-2 degrees C, respectively. Interference in analysis of caffeine due to different substrates was observed but was not considerable. Caffeine content of commercial samples of instant tea and coffee was analyzed by the biosensor and the results compared well with HPLC analysis.
Source : Anal Chim Acta 2007 vol.582 (2), pp 329 - 334
Dietary fiber in brewed coffee
Diaz-Rubio, M. E.; Saura-Calixto, F.
Coffee beans are rich in nondigestible polysaccharides (dietary fiber), which may partially pass into
brewed coffee; however, to the authors' knowledge, there is not enough literature on dietary fiber in
brewed coffee. A specific method to determine dietary fiber in beverages (enzymatic treatment plus
dialysis) was applied to the coffees brewed by the most common methods (espresso, filter, soluble);
results showed that brewed coffee contained a significantly higher amount of soluble dietary fiber (0.47-
0.75 g/100 mL of coffee) than other common beverages. Coffee dietary fiber contains a large amount of
associated antioxidant phenolics (8.7-10.5 mg/100 mL of brewed coffee).
Source : J Agric Food Chem 2007 vol.55 (5), pp 1999 - 2003
Free and bound 3-chloropropane-1,2-diol in coffee surrogates and malts
Divinova, V.; Dolezal, M.; Velisek, J
The known toxicity of 3-chloropropane-1,2-diol (3-MCPD), an acid hydrolysed vegetable protein, has
led to the establishment of tolerable daily intake limits. This study investigated the levels of free 3-MCPD
and its bound forms in five coffee surrogates and 18 malts available in the Czech Republic. The influence
of various factors, such as water, fat, glycerol and chloride, on the formation of bound 3-MCPD during
processing was also evaluated. The results found that the levels of free 3-MCPD in both malts and coffee
surrogates were below EU limits, the highest levels being found for roasted products; while the levels of
bound 3-MCPD were higher (32-81 times higher than free 3-MCPD levels in coffee surrogates and 0.4-36
times higher in malts), with the highest levels again being found in roasted products. The authors
recommend optimising roasting conditions to minimise contamination with 3-MCPD.
Source : Czech-Journal-of-Food-Sciences; 2007.25 (1), 39-47 (not available on-line)
Acrylamide levels in Finnish foodstuffs analysed with liquid chromatography tandem mass spectrometry
Eerola, S.; Hollebekkers, K.; Hallikainen, A.; Peltonen, K.
Concn. of acrylamide were determined in foods and beverages available on the Finnish market by HPLC with tandem MS using an in-house validated technique. 201 samples were analysed including, potato products, cereal products, meat products (including beef mince, chicken nuggets and bacon), pizza, popcorn, potato/ham casserole, coffee, tea and milk. Acrylamide concn. found ranged from nondetectable (e.g. in unfried bacon) to 1480 mug/kg in a crispbread sample. Potato chips, rye crisp bread and some biscuits tended to have the highest levels of acrylamide (>1000 mug/kg). Highest acrylamide concn. in beverages was found in a regular coffee drink (20 mug/l). The HPLC tandem MS technique used was sufficiently sensitive for routine monitoring; detection limits were 38 mug/kg and 5 mug/l for foods and beverages, respectively, while relative s.d. for repeatability and day-to-day variation were <15% in examined food samples.
Source : Mol Nutri Food Res 2007 vol.51(2), pp 239 - 247
Fingerprint developing of coffee flavor by gas chromatography-mass spectrometry and combined chemometrics methods
Huang, L. F.; Wu, M. J.; Zhong, K. J.; Sun, X. J.; Liang, Y. Z.; Dai, Y. H.; Huang, K. L.; Guo, F. Q.
In this paper, chromatographic fingerprint was firstly used for quality control of tobacco flavors. Based on gas chromatography-mass spectrometry (GC-MS) and combined chemometrics methods, a simple, reliable and reproducible method for developing chromatographic fingerprint of coffee flavor, one of tobacco flavors, was described. Six coffee flavor samples obtained from different locations were used to establish the fingerprint. The qualitative and quantitative analysis of coffee flavor sample from Shenzhen was completed with the help of subwindow factor analysis (SFA). Fifty-two components of 68 separated constituents in coffee flavor sample from Shenzhen, accounting for 88.42% of the total content, were identified and quantified. Then, spectral correlative chromatography (SCC) was used to extract the common peaks from other five studied coffee flavor samples. Thirty-eight components were found to exist in all six samples. Finally, the method validation of fingerprint analysis was performed based on the relative retention time and the relative peak area of common peaks, sample stability and similarity analysis. The similarities of six coffee flavor samples were more than 0.9104 and showed that samples from different locations were consistent to some extent. The developed chromatographic fingerprint was successfully used to differentiate coffee flavor from coco flavor and some little difference sample prepared with coffee flavor and coco flavor by both similarity comparison and principal component projection analysis. The developed method can be used for quality control of coffee flavor.
Source : Anal Chim Acta 2007 vol.588 (2), pp 216 - 223
An impression of coffee carbohydrates
Meenakshi, Arya; Mohan-Rao, L. J.
Coffee is one of the most popular beverages in the world, and is consumed for its refreshing and stimulating properties. In this article, the chemical composition and processing of coffee beans is reviewed. Aspects considered include: harvesting of coffee; processing (blending, roasting, grinding, brewing); chemical composition of coffee (moisture content, ash and minerals, non-protein N, proteins, phenols, volatiles); carbohydrate composition of green coffee, roasted coffee and instant coffee; functional properties of coffee carbohydrates; analytical techniques for the extraction, isolation and quantitative determination of carbohydrates from coffee; and the effect of coffee fibre on gastrointestinal bacteria.
Source : Crit Rev Food Sci Nutri 2007 vol.47(1): Issue 1 pp 51 - 67
Formation of 5-hydroxymethyl-2-furfural (HMF) and 5-hydroxymethyl-2-furoic acid during roasting of coffee
Murkovic, M.; Bornik, M. A.
The formation of 5-hydroxymethyl-2-furfural (HMF) and 5-hydroxymethyl-2-furoic acid (HMFA) during roasting of coffee was studied. At 240 degrees C the maximum concentration of HMF occurs after 3 min with a quick degradation up to 10 min when most of the HMF has disappeared again. Similar to 5-hydroxymethyl-furfural, HMFA is formed in coffee but not in a model system consisting of sucrose, alanine with or without chlorogenic acid. It was shown that HMFA is produced from different precursors than HMF namely glyceraldehyde and pyruvate. The comparison of the laboratory scale roasting with industrial roasting showed that 5-hydroxymethyl-furfural decreases with a higher degree of roasting whereas HMFA did not change. In the laboratory scale experiments, the highest concentration of 5-hydroxymethyl-furfural in coffee (909 mug/g) was obtained after 3 min and the maximum concentration of HMFA after 4 min (150 mug/g). Industrially roasted coffee contained up to 350 mug/g 5-hydroxymethyl-furfural and 140 mug/g HMFA.
Source : Mol Nutr Food Res 2007 vol.51 Issue 4 pp 390 - 394
Mixture resolution according to the percentage of robusta variety in order to detect adulteration in roasted coffee by near infrared spectroscopy
Pizarro, C.; Esteban-Diez, I.; Gonzalez-Saiz, J. M.
Development of a method for identifying roasted coffee of var. robusta, with potential for detecting adulteration of this coffee variety from other, cheaper, types of coffee, is reported. For this purpose, NIR spectra were generated for roasted robusta coffee and various multivariate calibration methods were applied for data pre-processing to develop a model for predicting the robusta variety content of a coffee sample. Pre-processing methods used were partial least squares for signal correction and OWAVEC, a recently developed wavelet-based method, for data compression. Mean centring, a 1st derivative method and 2 orthogonal correction methods were also applied to optimize predictive ability of the calibration model. The model developed showed root mean square of prediction, for determination of robusta coffee content, of 0.79%.
Source : Anal Chim Acta 2007 vol.585 (2), pp 266 - 276
Development and validation of a high-throughput high-performance liquid chromatographic assay for the determination of caffeine in food samples using a monolithic column
Tzanavaras, P. D.; Themelis, D. G.
The present study reports the development and validation of a high-throughput high-performance liquid chromatographic (HPLC) assay for the determination of caffeine in food samples. The analyte was separated rapidly from sample matrix using a short monolithic column (50mmx4.6mm i.d.). The flow rate was 3.0mLmin(-1), while the mobile phase consisted of ACN/water (10:90, v/v). Caffeine was detected directly at 274nm. Under the optimal HPLC conditions, the sampling rate was 60h(-1). The assay was validated for linearity, LOD and LOQ, precision, selectivity and ruggedness. The case of external calibration versus standard addition for the analysis of real samples was also examined. The proposed assay was applied to the analysis of beverages and coffee samples.
Source : Anal Chim Acta 2007 vol.581 (1), pp 89 - 94
Analysis of enantiomeric linalool ratio in green and roasted coffee
Bonnlander, B.; Cappuccio, R.; Liverani, F. S.; Winterhalter, P.
Linalool is one of the key aroma compounds in natural products, such as green and roasted coffee and, as plants usually produce one linalool isomer, enantiomeric excess can be used as an indicator of authenticity. This study examined the enantiomeric composition of linalool in green and roasted Arabica coffee and coffee beverages, using simultaneous distillation-extraction and stir-bar sorptive extraction in combination with multidimensional GC (MDGC) and MDGC-MS. Sensory impact of the two enantiomers was evaluated in water and by addition experiments to espresso beverages. Postharvest treatment of coffee shifted the enantiomeric ratio from racemic in washed coffee to an excess of S-(+)-linalool in dry processed coffee.
Source : Flav Fragr Journ 2006 vol.21 (4), pp 637-641
COFFEE & HEALTH
Effects of expectation and caffeine on arousal, well-being, and reaction time
Schneider, R.; Gruner, M.; Heiland, A.; Keller, M.; Kujanova, Z.; Peper, M.; Riegl, M.; Schmidt, S.; Volz, P.; Walach, H.
The objective of this study is to determine the impact of expectation associated with placebo and caffeine ingestion. We used a three-armed, randomized, double-blind design. Two three-armed experiments varying instruction (true, false, control) investigated the role of expectations of changes in arousal (blood pressure, heart rate), subjective well-being, and reaction time (RT). In Experiment 1 (N = 45),decaffeinated coffee was administered, and expectations were produced in one group by making them believe they had ingested caffeinated coffee. In Experiment 2 (N = 45), caffeinated orange juice was given in both experimental groups, but only one was informed about the true content. In Experiment 1, a significant effect for subjective alertness was found in the placebo treatment compared to the control group. However, for RT and well-being no significant effects were found. In Experiment 2, no significant expectancy effects were found. Caffeine produced large effects for blood pressure in both treatments compared to the control group, but the effects were larger for the false information group. For subjective well-being (alertness, calmness), considerable but nonsignificant changes were found for correctly informed participants, indicating possible additivity of pharmacologic effect and expectations. The results tentatively indicate that placebo and expectancy effects primarily show through introspection.
Source : Int J Behav Med 2006 vol.13 (4 ), pp 330 - 339
The effect of caffeine on handwriting movements in skilled writers
Tucha, O.; Walitza, S.; Mecklinger, L.; Stasik, D.; Sontag, T. A.; Lange, K. W.
In laboratory tasks, caffeine has been shown to improve psychomotor performance. The aim of the present experiment was to assess the effects of caffeine on a skilled everyday life task in habitual caffeine consumers. The assessment of handwriting movements of 20 adults was performed following the administration of 0mg/kg (placebo), 1.5mg/kg, 3.0mg/kg or 4.5mg/kg of caffeine. A digitising tablet was used for the assessment of fine motor movements. Participants were asked to perform a simple writing task. Kinematic analysis of handwriting movements showed that, in comparison to placebo administration, high doses of caffeine (i.e., 4.5mg/kg) can produce improvements in handwriting as indicated by more fluent handwriting movements as well as an increase in maximum velocity and maximum positive and negative accelerations. The results suggest that higher doses of caffeine can enhance psychomotor performance.
Source : Hum Mov Sci 2006 vol.25 (4-5), pp 523 - 535
Coffee consumption and the risk of gestational diabetes mellitus
Adeney, K. L.; Williams, M. A.; Schiff, M. A.; Qiu, C.; Sorensen, T. K.
Coffee consumption has been associated with a decreased risk of type 2 diabetes mellitus. We examined the relationship between coffee consumption and the risk of gestational diabetes mellitus [GDM]. METHODS: In this prospective study, 1744 non-diabetic pregnant women were questioned during early gestation about their coffee consumption. We studied the association of coffee consumption before and during pregnancy, and the subsequent risk of GDM. Generalised, linear models were fitted to estimate risk ratios and 95% confidence intervals. RESULTS: Women who reported moderate pre-pregnancy caffeinated coffee intake had a significantly reduced risk of GDM (adjusted RR 0.50; 95% CI 0.29-0.85) compared with non-consumers. No risk reduction was associated with decaffeinated coffee intake. CONCLUSIONS: Moderate pre-pregnancy caffeinated coffee consumption may have a protective association with GDM. Prospective studies, including a wider range of consumption habits, are necessary.
Source : Acta Obstet Gynecol Scand 2007 vol.86 (2), pp 161-166
Efficacy of a paracetamol and caffeine combination in the treatment of the key symptoms of primary dysmenorrhoea
Ali, Z.; Burnett, I.; Eccles, R.; North, M.; Jawad, M.; Jawad, S.; Clarke, G.; Milsom, I.
Primary dysmenorrhoea is characterised by pain, cramping and backache at the time of menses. Despite the high prevalence of dysmenorrhoea, few sufficiently powered, placebo-controlled studies have examined the efficacy of over the counter analgesics in this condition. Furthermore, even fewer studies have directly examined the efficacy of analgesics on specific dysmenorrhoea symptoms. Research design and main outcome measures: This was a single-dose, placebo-controlled, double blind, crossover study carried out in 320 women with moderate-to-severe dysmenorrhoea pain. At 2 h following dosing, 1 g paracetamol plus 130 mg caffeine led to significantly greater pain relief compared to 1 g paracetamol alone (p < 0.05), 130 mg caffeine alone (p < 0.01) or placebo (p < 0.01). The combination was also significantly more effective in relieving abdominal cramping and backache compared to the other treatment arms. No major treatment related adverse events were reported during this study.
CONCLUSIONS: When taken at recommended doses, both paracetamol and the combination of paracetamol and caffeine are safe and effective treatments for primary dysmenorrhoea. Consistent with results from other acute pain states, caffeine acts as an analgesic adjuvant and enhances the efficacy of paracetamol.
Source : Curr Med Res Opin 2007 vol.23 (4), pp 841 - 851
Differential responsiveness to caffeine and perceived effects of caffeine in moderate and high regular caffeine consumers
Attwood, A. S.; Higgs, S.; Terry, P.
Individual differences in responsiveness to caffeine occur even within a caffeine-consuming population, but the factors that mediate differential responsiveness remain unclear. OBJECTIVES: To compare caffeine's effects on performance and mood in a group of high vs moderate consumers of caffeine and to examine the potential role of subjective awareness of the effects of caffeine in mediating any differential responsiveness. MATERIALS AND METHODS: Two groups of regular caffeine consumers (<200 mg/day and >200 mg/day) attended two sessions at which mood and cognitive functions were measured before and 30 min after consumption of 400-mg caffeine or placebo in a capsule. Cognitive tests included visual information processing, match-to-sample visual search (MTS) and simple and choice reaction times. Post-session questionnaires asked participants to describe any perceived effect of capsule consumption. RESULTS: High consumers, but not moderate consumers, demonstrated significantly faster simple and choice reaction times after caffeine relative to placebo. These effects were not attributable to obvious group differences in withdrawal or tolerance because there were no group differences in baseline mood or in reports of negative affect after caffeine. Instead, the high consumers were more likely to report experiencing positive effects of caffeine, whereas the moderate consumers were more likely to report no effect. CONCLUSIONS: The sensitivity of caffeine consumers to the mood- and performance-enhancing effects of caffeine is related to their levels of habitual intake. High caffeine consumers are more likely than moderate consumers to perceive broadly positive effects of caffeine, and this may contribute to their levels of use.
Source : Psychopharmacology 2007 vol.190 (4), pp 469 - 477
Disruption of adenosinergic modulation of ventilation at rest and during hypercapnia by neonatal caffeine in young rats: role of adenosine A1 and A2A receptors
Montandon, G.; Kinkead, R.; Bairam, A.
Caffeine is commonly used to treat respiratory instabilities related to prematurity. However, the role of adenosinergic modulation and the potential long-term effects of neonatal caffeine treatment (NCT) on respiratory control are poorly understood. To address these shortcomings, we tested the following hypotheses: 1) adenosine A(1)- and A(2A)-receptor antagonists modulate respiratory activity at rest and during hypercapnia; 2) NCT has long-term consequences on adenosinergic modulation of respiratory control. Rat pups received by gavage either caffeine (15 mg/kg) or water (control) once a day from postnatal days 3 to 12. At day 20, rats received intraperitoneal injection with vehicle, DPCPX (A(1) antagonist, 4 mg/kg), or ZM-241385 (A(2A) antagonist, 1 mg/kg) before plethysmographic measurements of resting ventilation, hypercapnic ventilatory response (5% CO(2)), and occurrence of apneas in freely behaving rats. In controls, data show that A(2A), but not A(1), antagonist decreased resting ventilation by 31% (P = 0.003). A(1) antagonist increased the hypercapnic response by 60% (P < 0.001), whereas A(2A) antagonist increased the hypercapnic response by 42% (P = 0.033). In NCT rats, A(1) antagonist increased resting ventilation by 27% (P = 0.02), but the increase of the hypercapnic response was blunted compared with controls. A(1) antagonist enhanced the occurrence of spontaneous apneas in NCT rats only (P = 0.005). Finally, A(2A) antagonist injected in NCT rats had no effect on ventilation. These data show that hypercapnia activates adenosinergic pathways, which attenuate responsiveness (and/or sensitivity) to CO(2) via A(1) receptors. NCT elicits developmental plasticity of adenosinergic modulation, since neonatal caffeine persistently decreases ventilatory sensitivity to adenosine blockers.
Source : Am J Physiol Regul Integr Comp Physiol 2007 vol.292 (4), pp R1621 - R1631
Coffee and tea consumption and risk of hepatocellular carcinoma in Italy
Montella, M.; Polesel, J.; La Vecchia, C.; Dal Maso, L.; Crispo, A.; Crovatto, M.; Casarin, P.; Izzo, F.; Tommasi, L. G.; Talamini, R.; Franceschi, S.
The role of coffee in the aetiology of hepatocellular carcinoma has raised great interest. In Italy, coffee consumption is high, thus allowing the investigation of the topic over a broad range of consumption. A hospital-based case-control study was conducted in Italy in 1999-2002, including 185 incidents, histologically confirmed cases of hepatocellular carcinoma aged 43-84 years. Controls were 412 subjects admitted to the same hospitals' networks for acute, non-neoplastic diseases unrelated to diet. Coffee and tea consumption were assessed using a validated food-frequency questionnaire. Odds ratios (ORs) and corresponding the 95% confidence intervals (CI) were computed using unconditional multiple logistic regression, adjusting for hepatitis viruses seropositivity, alcohol intake, smoking habits and other potential confounding factors. Compared to people who drunk <14 cups/week of coffee, the risk of hepatocellular carcinoma decreased for increasing levels of consumption (OR=0.4, 95% CI: 0.2-1.1 for >or=28 cups/week, p for trend = 0.02). In the present study, inverse relations were observed across strata of hepatitis C and, B virus infections and alcohol drinking. No significant association emerged with consumption of decaffeinated coffee (OR=0.7, 95% CI=0.2-2.5) or tea (OR=1.4, 95% CI=0.8-2.7). The present study supports the hypothesis of a favourable effect of coffee, though not decaffeinated coffee and tea, on the risk on hepatocellular carcinoma.
Source : Int J Cancer 2007 vol.120 (7), pp 1555 - 1559
Consumption of black tea or coffee and risk of ovarian cancer
Baker, J. A.; Boakye, K.; McCann, S. E.; Beehler, G. P.; Rodabaugh, K. J.; Villella, J. A.; Moysich, K. B.
The goal of this study was to investigate the associations between ovarian cancer risk and usual consumption of black tea, regular coffee, or decaffeinated coffee. Using a hospital-based case-controldesign, participants included 414 women with primary epithelial ovarian, fallopian, or peritoneal cancer and 868 age- and region-matched women with nonneoplastic conditions. All participants completed a comprehensive epidemiologic questionnaire. Black tea consumption was associated with a linear decline in ovarian cancer risk (P for trend 0.03), with individuals consuming two or more cups daily experiencing a 30% decline in risk (adjusted OR 0.70, 95% CI 0.51-0.97). Similar declines were noted among individuals consuming two or more cups of decaffeinated coffee daily (adjusted OR 0.71, 95% CI 0.51-0.99; P for trend 0.002). However, no association was noted between any level of regular coffee consumption and risk of ovarian cancer. The chemoprotective effects of phytochemicals in black tea and decaffeinated coffee may be important, although the effects of phytochemicals in regular coffee may be counteracted by the elevated risk associated with its higher caffeine content.
Source : Int J Gynecol Cancer 2007 vol.17 (1), pp 50 - 54
Sustained improvement of motor function in hemiparkinsonian rats chronically treated with low doses of
Bata-Garcia, J. L.; Villanueva-Toledo, J.; Gutierrez-Ospina, G.; Alvarez-Cervera, F. J.; Heredia-Lopez, F.J.; Gongora-Alfaro, J. L.
The effects of chronic oral treatment with low doses of caffeine (1-3 mg/kg) and trihexyphenidyl (0.1-0.2 mg/kg) were tested on hemiparkinsonian rats, which received the following treatments in a counterbalanced order: vehicle, caffeine, trihexyphenidyl, and caffeine plus trihexyphenidyl. Three preclinical models were used: the stepping test, the cylinder test, and the staircase test. Compared to prelesion values, the forepaw contralateral to the dopamine-denervated side showed impaired stepping, fewer wall contacts in the cylinder test, and fewer pellets retrieved in the staircase test. In the stepping test both doses of caffeine produced a complete recovery of motor function (100%), whereas the effect of trihexyphenidyl was less intense (77-80%). In this same test the maximal effect of drugs did not develop tolerance during 2-3 weeks, and was completely reversible after drug cessation. In the cylinder test only the wall contacts performed simultaneously with both forepaws were significantly increased by caffeine (3 mg/kg) and trihexyphenidyl (0.2 mg/kg), and this effect was also reversible. In the staircase test none of the treatments improved food pellet retrieval with the contralateral forepaw. Altogether, these results show that chronic treatment with caffeine, at doses similar to daily human consumption, produces a sustained improvement in the use of the contralateral forelimb in unilaterally 6-hydroxydopamine denervated rats, without the development of tolerance. Although the combined administration of caffeine plus trihexyphenidyl showed no synergism in these models, the results suggest that low doses of caffeine (1-3 mg/kg/day) could be of therapeutic value for the reversal of motor symptoms in parkinsonian patients.
Source : J Appl Physiol 2007 vol.102 Issue 1 pp 374 - 381
Acute caffeine ingestion does not impair glucose tolerance in persons with tetraplegia
Battram, D. S.; Bugaresti, J.; Gusba, J.; Graham, T. E.
Acute caffeine (Caf) ingestion impairs glucose tolerance in able-bodied humans during an oral glucose tolerance test (OGTT). The mechanism responsible for this effect remains unclear, however, it is suggested to be due to the accompanying increase in epinephrine concentration. We examined whether or not Caf would elicit a glucose intolerance in persons with tetraplegia (TP) who do not exhibit an increased epinephrine response following Caf ingestion. All TP [n = 14; 9 incomplete (Inc) lesion, 5 complete (Com) lesion] completed two OGTT 1 h after consuming either gelatin (Pl) or Caf capsules (dose = 4 mg/kg). Blood samples were collected at baseline (time = 0 min), 1 h after capsule ingestion (time = 60 min), and every 30 min during the OGTT (time = 90-180 min). Glucose, insulin, proinsulin, and C-peptide responses were similar (P > 0.05) between treatments, demonstrating no effect of Caf on glucose tolerance. This lack of a Caf effect may be due to the low epinephrine concentration that remained unchanged (P > 0.05) throughout all experiments. Interestingly, the Com exhibited a 50% higher glucose response (P <or= 0.05) and a 46% (P > 0.05) lower insulin response (vs. Inc), suggesting a more pronounced glucose intolerance within this subgroup. Furthermore, nine TP (5 Com, 4 Inc) had glucose levels of >or= 7.8 mM at the end of the OGTT (time = 180 min), classifying them as glucose intolerant. In summary, acute Caf ingestion does not increase epinephrine concentration or impair glucose tolerance in TP.
Source : J Appl Physiol 2007 vol.102 (1), pp 374 - 381
Effect of reducing caffeine intake on birth weight and length of gestation: randomised controlled trial
Bech, B. H.; Obel, C.; Henriksen, T. B.; Olsen, J.
A randomized double-blind controlled trial was conducted to assess effects of reducing caffeine intake during pregnancy on birth wt. and length of gestation. 1207 pregnant women drinking <greater than or equal to>3 cups of coffee daily, recruited before 20 wk gestation, participated. 568 women received instant coffee containing caffeine, and 629 received decaffeinated instant coffee. Data on live wt. were obtained for 1150 liveborn singletons, and data on length of gestation were obtained for 1153 liveborn singletons. No significant differences in either wt. or gestation length were observed between the 2 groups of women. It is concluded that a moderate reduction in caffeine intake during the 2nd half of pregnancy had no effect on birth wt. or gestation length.
Source : British Medical Journal.2007 vol.334 (7590), pp 409
The effect of caffeine on dilated cerebral circulation and on diagnostic CO(2) reactivity testing
Blaha, M.; Benes, V.; Douville, C. M.; Newell, D. W.
Reduction of cerebral blood flow by caffeine has been shown in multiple studies. However, the effect of this substance on pathologically dilated cerebral vessels is not clearly defined. The aim of this study was to investigate the effect of caffeine on an already dilated cerebral circulation and specify if these vessels are still able to constrict as a consequence of caffeine stimulation. A second aim of this study was to compare results of cerebral vasomotor CO(2) reactivity testing with and without caffeine ingestion. Seventeen healthy adult volunteers had vasomotor reactivity tested before and thirty minutes after ingestion of 300 mg of caffeine. Each vasomotor reactivity test consisted of velocity measurements from both middle cerebral arteries using transcranial Doppler ultrasound during normocapnia, hypercapnia, and hypocapnia. Hemodynamic data and end-tidal CO(2) (etCO(2)) concentration were also recorded. The vasomotor reactivity (VMR) and CO(2) reactivity were calculated from a measured data pool. At a level of etCO(2)=40 mmHg the resting velocity in the middle cerebral artery (V(MCA)) dropped from 70.7+/-22.8 cm/sec to 60.7 +/- 15.4 cm/sec 30 minutes after caffeine stimulation (14.1% decrease, p<0.001). During hypercapnia of etCO(2)=50 mmHg there was also a significant decline of V(MCA) from 103.1+/-25.4 to 91.4+/-21.8 cm/sec (11.3%, p<0.001). There was not a statistically significant reduction of V(MCA) during hypocapnia. Calculated VMR and CO(2) reactivity before and after caffeine intake were not statistically significant. The presented data demonstrate a significant decrease in cerebral blood flow velocities after caffeine ingestion both in a normal cerebrovascular bed and under conditions of peripheral cerebrovascular vasodilatation. These findings support the important role of caffeine in regulation of CBF under different pathological conditions. Despite significant reactive vasodilatation in the brain microcirculation, caffeine is still able to act as a competitive antagonist of CO(2) on cerebral microvessels. The fact that caffeine may decrease CBF despite significant pathological vasodilatation offers the possibility of therapeutic manipulation in patients with traumatic vasoparalysis. For routine clinical testing of CO(2) reactivity it is not necessary to insist on pre-test dietary restrictions.
Source : J Clin Neurosci 2007 vol.14 (5), pp 464 - 467
The enigmatic effects of caffeine in cell cycle and cancer
Bode, A. M.; Dong, Z.
Caffeine may very well be the most frequently ingested neuroactive drug in the world. Mechanistically, caffeine has been reported to affect cell cycle function, induce programmed cell death or apoptosis and perturb key cell cycle regulatory proteins. Although the effects of caffeine have been heavily investigated, much of the research data regarding caffeine's effects on cell cycle and proliferation seem ambiguous. One important factor may be that caffeine has been used experimentally in numerous cell types under a variety of conditions at concentrations ranging from micromolar to high millimolar. Physiologically, achieving experimental blood levels of caffeine would be extremely difficult without adverse side effects. Therefore, the relevance of experimental data obtained by using high concentrations of caffeine is not clear and may account for some of the discrepancies in the literature. This review attempts to reconcile data regarding the cellular effects of caffeine by examining reported effects on cell cycle, proliferation and apoptosis with careful attention to differences in experimental conditions and caffeine concentration utilized.
Source : Cancer Lett vol.247 (1), pp 26 - 39
Effects of caffeine are more marked on daytime recovery sleep than on nocturnal sleep
Carrier, J.; Fernandez-Bolanos, M.; Robillard, R.; Dumont, M.; Paquet, J.; Selmaoui, B.; Filipini, D.
Caffeine is often used to counteract sleepiness generated by sleep deprivation, jet lag, and shift-work, and is consumed at different times of day. Caffeine also has effects on sleep. However, little is known about the interaction between sleep deprivation, circadian timing, and caffeine consumption on sleep. In this study, we compared the effects of caffeine on nocturnal sleep initiated at habitual circadian time and on daytime recovery sleep. Thirty-four moderate caffeine consumers participated in both caffeine (200 mg) and placebo (lactose) conditions in a double-blind crossover design. Seventeen subjects followed their habitual sleep-wake cycle and slept in the laboratory during the night (Night), while 17 subjects were sleep deprived for one night and recovery sleep started in the morning (DayRec). All subjects received a capsule of 100 mg of caffeine (or placebo) 3 h before bedtime, and the remaining dose 1 h before bedtime. Compared to placebo, caffeine lengthened sleep latency, increased stage 1, and reduced stage 2 and slow-wave sleep (SWS) in both groups. However, caffeine reduced sleep efficiency more strongly in the DayRec group, and decreased sleep duration and REM sleep only in that group. The stronger effects of caffeine on daytime recovery sleep compared to nocturnal sleep are probably the consequence of the combined influence of increasing circadian wake propensity drive and the dissipation of homeostatic sleep pressure. We propose that the reduction of SWS by caffeine during daytime sleep increases the impact of the circadian wake signal on sleep. These results have implications for individuals using caffeine during night time.
Source : Neuropsychopharmacology 2007 vol.32 (4), pp 964 - 972
Coffee, caffeine, and coronary heart disease
Cornelis, M. C.; El Sohemy, A.
This review summarizes and highlights recent advances in current knowledge of the relationship between coffee and caffeine consumption and risk of coronary heart disease. Potential mechanisms and genetic modifiers of this relationship are also discussed. RECENT FINDINGS: Studies examining the association between coffee consumption and coronary heart disease have been inconclusive. Coffee is a complex mixture of compounds that may have either beneficial or harmful effects on the cardiovascular system. Randomized controlled trials have confirmed the cholesterol-raising effect of diterpenes present in boiled coffee, which may contribute to the risk of coronary heart disease associated with unfiltered coffee consumption. A recent study examining the relationship between coffee and risk of myocardial infarction incorporated a genetic polymorphism associated with a slower rate of caffeine metabolism and provides strong evidence that caffeine also affects risk of coronary heart disease. Several studies have reported a protective effect of moderate coffee consumption, which suggests that coffee contains other compounds that may be beneficial. SUMMARY: Diterpenes present in unfiltered coffee and caffeine each appear to increase risk of coronary heart disease. A lower risk of coronary heart disease among moderate coffee drinkers might be due to antioxidants found in coffee.
Source : Curr Opin Lipidol. 2007 vol.18 (1), pp 13 - 19
Caffeine promotes apoptosis in mitotic spindle checkpoint-arrested cells
Gabrielli, B.; Yu, Qian Chau; Giles, N.; Harding, A.; Stevens, F.; Beamish, H.
The spindle assembly checkpoint arrests cells in mitosis when defects in mitotic spindle assembly or partitioning of the replicated genome are detected. This checkpoint blocks exit from mitosis until the defect is rectified or the cell initiates apoptosis. This study used caffeine to identify components of the mechanism that signals apoptosis in mitotic checkpoint-arrested cells. Addition of caffeine to spindle checkpoint-arrested cells induced >40% apoptosis within 5 h. It also caused proteasome-mediated destruction of cyclin B1, a corresponding reduction in cyclin B1/cdk1 activity, and a reduction in MPM-2 reactivity. However, cells retained MAD2 staining at the kinetochores, an indication of continued spindle checkpoint function. Blocking proteasome activity did not block apoptosis, but continued spindle checkpoint function was essential for apoptosis. After systematically eliminating all known targets, identified p21-activated kinase PAK1, which has an anti-apoptotic function in spindle checkpoint-arrested cells, was identified as a target for caffeine inhibition. Knockdown of PAK1 also increased apoptosis in spindle checkpoint-arrested cells. This study demonstrates that the spindle checkpoint not only regulates mitotic exit but apoptosis in mitosis through the activity of PAK1.
Source : J Biol Chem 2007 vol.282(10), pp 6954 - 6964
Caffeinated beverage intake and the risk of heart disease mortality in the elderly: a prospective analysis
Greenberg, J. A.; Dunbar, C. C.; Schnoll, R.; Kokolis, R.; Kokolis, S.; Kassotis, J.
Motivated by the possibility that caffeine could ameliorate the effect of postprandial hypotension on a high risk of coronary events and mortality in aging, we hypothesized that caffeinated beverage consumption decreases the risk of cardiovascular disease (CVD) mortality in the elderly. OBJECTIVE: The objective of the study was to use prospective cohort study data to test whether the consumption of caffeinated beverages exhibits this protective effect. DESIGN: Cox regression analyses were conducted for 426 CVD deaths that occurred during an 8.8-y follow-up in the prospective first National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. The analysis involved 6594 participants aged 32-86 y with no history of CVD at baseline. RESULTS: Participants aged >or=65 y with higher caffeinated beverage intake exhibited lower relative risk of CVD and heart disease mortality than did participants with lower caffeinated beverage intake. It was a dose-response protective effect: the relative risk (95% CI) for heart disease mortality was 1.00 (referent), 0.77 (0.54, 1.10), 0.68 (0.49, 0.94), and 0.47 (0.32, 0.69) for <0.5, 0.5-2, 2-4, and >or=4 servings/d, respectively (P for trend = 0.003). A similar protective effect was found for caffeine intake in mg/d. The protective effective was found only in participants who were not severely hypertensive. No significant protective effect was found in participants aged <65 y or in cerebrovascular disease mortality for those aged >or=65 y. CONCLUSION: Habitual intake of caffeinated beverages provided protection against the risk of heart disease mortality among elderly participants in this prospective epidemiologic analysis.
Source : Am J Clin Nutr vol.85 Issue 2 pp 392 - 398
[Coffee and pregnancy.]
Hey, E.
Potential health impacts of consumption of coffee or caffeine during pregnancy are discussed with reference to the article of Bech et al. [see FSTA 2007-05-Hn1884] showing that a moderate reduction in caffeine intake during the 2nd half of pregnancy had no effect on birth wt. or gestation length.
Source : Brit Med Journ 2007 vol.334 (7590), pp 377
Habitual coffee but not green tea consumption is inversely associated with metabolic syndrome An epidemiological study in a general Japanese population
Hino, A.; Adachi, H.; Enomoto, M.; Furuki, K.; Shigetoh, Y.; Ohtsuka, M.; Kumagae, S.; Hirai, Y.; Jalaldin, A.; Satoh, A.; Imaizumi, T.
In Japan, metabolic syndrome used to be rare, and the level of coffee consumption was low. However, the Japanese life style has been changing rapidly, and these changes have been associated with a steady increase in the frequency of metabolic syndrome and with greater consumption of coffee. We examined the relationship between metabolic syndrome and the consumption of coffee or green tea. A total of 1902 Japanese aged over 40 years (785 men and 1117 women) received population-based health check-up in 1999. We measured components of metabolic syndrome (blood pressure, waist circumference, fasting plasma glucose, and lipid profiles). Eating and drinking patterns were evaluated by a food frequency questionnaire. Multivariate analyses were performed to clarify the association between coffee or green tea consumption and the components of metabolic syndrome. All components of metabolic syndrome except for HDL-cholesterol were significantly (p<0.01) and inversely related to coffee but not green tea consumption by multivariate analysis after adjusting for confounding factors. The larger was the number of components of metabolic syndrome, the lower was the level of coffee consumption (p<0.0001). In addition, there was a high frequency of metabolic syndrome in small coffee drinkers. Thus, coffee but not green tea consumption was inversely associated with metabolic syndrome.
Source : Diabetes Res Clin Pract 2007 vol.76 (3), pp 383 - 389
Coffee consumption and the risk of endometrial cancer: Evidence from a case-control study of female hormone-related cancers in Japan
Hirose, K.; Niwa, Y.; Wakai, K.; Matsuo, K.; Nakanishi, T.; Tajima, K.
Coffee has become a popular beverage worldwide. Caffeine, a major ingredient of coffee, has beenproposed to have a favorable affect on the modulation of circulating estrogen levels and therefore may be of importance in developments on hormone-related cancers. However, epidemiological evidence is limited and inconsistent. We examined the relationship between intake of coffee and hormone-related cancer risk among Japanese women using data from the hospital-based epidemiological research program at Aichi Cancer Center (HERPACC). In total, 2122 breast, 229 endometrial and 166 ovarian cancer cases were included, and 12 425 women, confirmed as free of cancer, were recruited as the control group. Odds ratios (OR) and 95% confidence intervals (95% CI) were determined by multiple logistic regression analysis. A statistically significant inverse association between risk of endometrial cancer and coffee consumption was noted in Japanese women, with no clear association evident for breast and ovarian cancer risk. Compared to non-drinker, the OR of daily drinking of 1-2 cups and 3 or more cups per day for endometrial cancer were 0.64 (95% CI: 0.43-0.94) and 0.41 (95% CI: 0.19-0.87), respectively, and the linear trend was also statistically significant (P < 0.01). However, there was no statistically significant association between caffeine intake and endometrial cancer. In summary, the results of the present study suggest that coffee consumption reduces the risk of endometrial cancer in Japanese subjects. Given the scarcity of studies of coffee intake and endometrial cancer and other hormone-dependent cancer risk, additional investigations are warranted.
Source : Cancer Sci 2007 vol.98 (3), pp 411 - 415
Evaluation of cardiovascular effects of caffeine using telemetric monitoring in the conscious rat
Ilback, N. G.; Siller, M.; Stalhandske, T.
Caffeine (1,3,7 trimethylxanthine) affects the cardiovascular system, with potential toxic effects ranging from a moderate increase in heart rate to more severe cardiac arrhythmias. Telemetry transmitters were implanted in Wistar rats in the peritoneal cavity with a pressure catheter in the aorta and electrodes for electrocardiogram (ECG) recording subcutaneously. After a single oral administration of saline, each rat was administered single oral doses of 5, 15 and 45mg/kg b.w. of caffeine. Caffeine was found to induce, to various degrees, a dose-dependent early increase in spontaneous physical activity, heart rate, dp/dt and systolic-diastolic blood pressure. No arrhythmias or visual changes were observed in the ECG complex. High doses induced more strong responses and of longer duration. The increase in systolic blood pressure at the median dose remained in the rats until 20h after administration. However, the highest dose of caffeine (45mg/kg b.w.) induced a biphasic response, with an early and pronounced increase in body temperature, spontaneous physical activity, systolic and diastolic blood pressure that later decreased, except for the systolic blood pressure. The results show that the dose level for longlasting signs of intoxication to develop in the rat, in terms of effects on spontaneous physical activity, body temperature and cardiovascular function, was reached after a single oral dose of caffeine at 45mg/kg b.w.
Source : Food Chem Toxicol 2007 vol.45 (5), pp 834 - 842
Crossover, double-blind clinical trial comparing almotriptan and ergotamine plus caffeine for acute migraine therapy
Lainez, M. J.; Galvan, J.; Heras, J.; Vila, C.
In this randomized, double-blind, crossover clinical trial, adult patients treated two migraine attacks: one with almotriptan 12.5 mg and the other with ergotamine 2 mg plus caffeine 200 mg. Treatment with almotriptan was associated with a significantly greater proportion of patients achieving 2-h pain free (20.9% vs. 13.7%; P < 0.05) and 2-h pain relief (57.7% vs. 44.5%; P < 0.01) compared with ergotamine plus caffeine therapy; significant differences were not seen at 1 h. Rates for sustained pain free and sustained pain free plus no adverse events (AEs) also were significantly greater after almotriptan treatment than after the use of ergotamine plus caffeine (P < 0.05). Almotriptan was associated with a significantly lower rate of photophobia at 90 min (P < 0.05), phonophobia at 60, 90, and 120 min (P < 0.05 to <0.01), and nausea and vomiting at 90 and 120 min (P < 0.01) compared with ergotamine plus caffeine. significantly greater proportion of patients were more satisfied with almotriptan than with ergotamine plus caffeine (P < 0.05). Sixteen patients reported adverse events during almotriptan treatment and 27 patients reported AEs during the ergotamine plus caffeine therapy. Most AEs were mildto-moderate and did not result in treatment-related discontinuations. In conclusion, almotriptan was associated with significantly greater efficacy for treating migraine compared with ergotamine plus caffeine, was generally well tolerated and was associated with greater rate of treatment satisfaction.
Source : Eur J Neurol 2007 14 (3), pp 269 - 275
Serum caffeine concentrations in preterm neonates
Leon, A. E.; Michienzi, K.; Ma, C. X.; Hutchison, A. A.
Caffeine therapy reduces apnea of prematurity, promotes successful extubation from invasive positivepressure ventilation, and decreases the incidence of bronchopulmonary dysplasia. The recommended dosing for caffeine is a loading dose of 20 mg/kg followed by a 5 mg/kg/d maintenance dose. However, controversy exists about the optimal dosing regimen and data on serum caffeine concentrations in extremely immature infants are scant. We determined serum caffeine concentrations approximately 7 days after starting therapy with a 20 or 25 mg/kg loading dose and a 6 mg/kg/d maintenance dose in 154 infants with a mean gestational age of 29 weeks. The 25th to 75th percentile range for the serum caffeine concentrations with the two dosing regimens was equivalent, approximately 18 to 23 mg/L. Within the first 14 postnatal days, the serum caffeine concentrations were not dependent on postmenstrual age, weight, or postnatal age, and were in a range that is safe and therapeutic. This latter observation remained valid over the ranges of clinical and laboratory assessments of renal and hepatic functions that are usually found in practice. Routine measurement of steady-state serum caffeine concentrations in infants 24 to 35 weeks gestational age is not required in the absence of ongoing apnea/hypopnea or signs compatible with toxicity.
Source : Am J Perinatol 2007 vol.24 (1), pp 39 - 47
Caffeine attenuates delayed-onset muscle pain and force loss following eccentric exercise
Maridakis, V.; O'connor, P. J.; Dudley, G. A.; McCully, K. K.
This double-blind, placebo-controlled, repeated-measures experiment examined the effects of a 5 mg . 64 eccentric actions of the dominant quadriceps induced by electrical stimulation. Low caffeine23 consuming college-aged females (n = 9) ingested caffeine or placebo 24 and 48 hours following electrically stimulated eccentric exercise of the quadriceps. One hour after ingestion, maximal voluntary isometric contractions (MVIC) and submaximal voluntary eccentric actions were used to determine force loss during activation of damaged quadriceps and whether caffeine attenuates muscle pain intensity. Pain intensity was measured using a 0 to 100 visual analog scale. Caffeine produced a large (12.7 raw visual analog scale [VAS] units; -48%; Cohen's d effect size = -0.88), statistically significant hypoalgesia during the MVIC (t = -2.52; df = 8; P = .036). The reduction in pain scores during submaximal voluntary eccentric movements was smaller (7.8 raw VAS units; -26%, d = -0.34), as was the increase in MVIC force (4.4%; d = 0.13). PERSPECTIVE: Eccentric exercise occurs when skeletal muscles produce force while being lengthened. For example, the biceps brachii muscles act eccentrically when a cup of coffee is lowered from the mouth to a tabletop. This experiment found that caffeine (equal to approximately 2 cups of brewed coffee) could produce a large reduction in pain resulting from eccentric exercise-induced, delayed-onset muscle injury. This finding may improve the quality of life of individuals who experience skeletal muscle pain after engaging in unaccustomed, eccentrically biased exercise.
Source : J Pain 2007 vol.8 (3), pp 237 - 243
Caffeine induces a profound and persistent tachycardia in response to MDMA (\"Ecstasy\") administration
McNamara, R.; Maginn, M.; Harkin, A
Caffeine promotes hyperthermia and lethality when co-administered with the recreational drug 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") to rats. In the present study, co-administration of caffeine (10 mg/kg, s.c.) with MDMA (10 mg/kg, s.c.) induced a profound tachycardic response compared to rats treated with either drug alone. However, neither caffeine (30 microM) nor MDMA (1-30 microM), alone or in combination, affected the electrocardiogram of the isolated heart suggesting that central and sympathomimetic actions, rather than direct actions of these drugs on the heart, are responsible for the tachycardia observed in vivo. This is a serious drug interaction, which could have important health consequences for recreational drug users.
Source : Eur J Pharmacol 2007 vol.555 (2-3), pp 194 - 198
Sequential updating of a new dynamic pharmacokinetic model for caffeine in premature neonates
Micallef, S.; Amzal, B.; Bach, V.; Chardon, K.; Tourneux, P.; Bois, F. Y.
Caffeine treatment is widely used in nursing care to reduce the risk of apnoea in premature neonates. To check the therapeutic efficacy of the treatment against apnoea, caffeine concentration in blood is an important indicator. The present study was aimed at building a pharmacokinetic model as a basis for a medical decision support tool. METHODS: In the proposed model, time dependence of physiological parameters is introduced to describe rapid growth of neonates. To take into account the large variability in the population, the pharmacokinetic model is embedded in a population structure. The whole model is inferred within a Bayesian framework. To update caffeine concentration predictions as data of an incoming patient are collected, we propose a fast method that can be used in a medical context. This involves the sequential updating of model parameters (at individual and population levels) via a stochastic particle algorithm. RESULTS: Our model provides better predictions than the ones obtained with models previously published. We show, through an example, that sequential updating improves predictions of caffeine concentration in blood (reduce bias and length of credibility intervals). The update of the pharmacokinetic model using body mass and caffeine concentration data is studied. It shows how informative caffeine concentration data are in contrast to body mass data.
CONCLUSION: This study provides the methodological basis to predict caffeine concentration in blood, after a given treatment if data are collected on the treated neonate.
Source : Clin Pharmacokinet 2007 vol.46 (1), pp 59 - 74
Postulated role of interdomain interaction between regions 1 and 2 within type 1 ryanodine receptor in the
Murayama, T.; Oba, T.; Hara, H.; Wakebe, K.; Ikemoto, N.; Ogawa, Y.
We have demonstrated recently that CICR (Ca2+-induced Ca2+ release) activity of RyR1 (ryanodine receptor 1) is held to a low level in mammalian skeletal muscle ('suppression' of the channel) and that this is largely caused by the interdomain interaction within RyR1 [Murayama, Oba, Kobayashi, Ikemoto and Ogawa (2005) Am. J. Physiol. Cell Physiol. 288, C1222-C1230]. To test the hypothesis that aberration of this suppression mechanism is involved in the development of channel dysfunctions in MH (malignant hyperthermia), we investigated properties of the RyR1 channels from normal and MHS (MH-susceptible) pig skeletal muscles with an Arg615-->Cys mutation using [3H]ryanodine binding, single-channel recordings and SR (sarcoplasmic reticulum) Ca2+ release. The RyR1 channels from MHS muscle (RyR1MHS) showed enhanced CICR activity compared with those from the normal muscle (RyR1N), although there was little or no difference in the sensitivity to several ligands tested (Ca2+, Mg2+ and adenine nucleotide), nor in the FKBP12 (FK506-binding protein 12) regulation. DP4, a domain peptide matching the Leu2442-Pro2477 region of RyR1 which was reported to activate the Ca2+ channel by weakening the interdomain interaction, activated the RyR1N channel in a concentration-dependent manner, and the highest activity of the affected channel reached a level comparable with that of the RyR1MHS channel with no added peptide. The addition of DP4 to the RyR1MHS channel produced virtually no further effect on the channel activity. These results suggest that stimulation of the RyR1MHS channel caused by affected inter-domain interaction between regions 1 and 2 is an underlying mechanism for dysfunction of Ca2+ homoeostasis seen in the MH phenotype.
Source : Biochem J 2007 vol.402 (2), pp 349 - 357
Coffee consumption and the risk of colorectal cancer: a prospective cohort study in Japan
Naganuma, T.; Kuriyama, S.; Akhter, M.; Kakizaki, M.; Nakaya, N.; Matsuda-Ohmori, K.; Shimazu, T.; Fukao, A.; Tsuji, I.
An inverse association between coffee consumption and the risk of colorectal cancer has been reported in several case-control studies, but results from prospective cohort studies have been inconclusive. We conducted a prospective cohort study among a Japanese population to clarify the association between coffee consumption and the risk of colorectal cancer incidence. We used data from the Miyagi Cohort Study for this analysis. Usable self-administered questionnaires about coffee consumption were returned from 22,836 men and 24,769 women, aged 40-64 years, with no previous history of cancer. We used the Cox proportional-hazard regression model to estimate hazard ratios and 95% confidence intervals. During 11.6 years of follow-up (425,303 person-years), we identified 457 cases of colorectal cancer. Coffee consumption was not associated with the incidence of colorectal, colon or rectal cancer. The multivariateadjusted hazard ratio (95% confidence interval) of colorectal cancer incidence for 3 or more cups of coffee per day as compared with no consumption was 0.95 (0.65-1.39) for men and women (p for trend = 0.55), 0.91 (0.56-1.46) for men (p for trend = 0.53) and 1.16 (0.60-2.23) for women (p for trend = 0.996). Coffee consumption was also not associated with incidence of either proximal or distal colon cancer. We conclude that coffee consumption is not associated with the incidence risk of colorectal cancer in the general population in Japan.
Source : Int J Cancer 2007 vol.120 (7), pp 1542 - 1547
Night-time thoughts in high and low worriers: Reaction to caffeine-induced sleeplessness
Omvik, S.; Pallesen, S.; Bjorvatn, B.; Thayer, J.; Hilde-Nordhus, I.
There is ample evidence for the existence of an association between sleeplessness and worry. Not much is known, however, concerning the nature of this relationship. Therefore, a study was conducted investigating the causal relationship between sleeplessness and nocturnal worry. A 2x2 (WorryxInduced sleeplessness) analysis of covariance design was used. The first factor consisted of a subject variable defined by scoring either high or low on a trait measure of worry (the Penn State Worry Questionnaire) and the second factor consisted of 300mg caffeine or placebo. A total of 96 female undergraduate students participated. The dependent variables comprised measures of nocturnal worry (the Night-Time Thoughts Questionnaire) and subjective and objective sleep parameters. Overall, caffeine caused an increase in nocturnal worry and sleeplessness. A significant interaction effect occurred between Worry and Induced sleeplessness on one of the objective sleep parameters, but no other interaction effects were significant. The results suggest that worry may occur as an epiphenomenon of sleeplessness.
Source : Behav Res Ther vol.45 Issue 4 pp 715 - 727
A translational, caffeine-induced model of onset insomnia in rats and healthy volunteers
Paterson, L. M.; Wilson, S. J.; Nutt, D. J.; Hutson, P. H.; Ivarsson, M.
Insomnia is a common and disabling complaint for which there is a need for improved treatments. Successful drug discovery relies on the use of appropriate animal models to assess likely outcome in the clinic. OBJECTIVES: The purpose of this study was to develop a translational, caffeineinduced model of insomnia in rats and healthy volunteers. We used sleep onset latency (SOL) as a comparable sleep measure between the two species. The model was validated by two effective sleep promoting agents with different pharmacology, zolpidem and trazodone, which have GABA-ergic and serotonergic mechanisms, respectively. MATERIALS AND METHODS: In rats, radiotelemetry transmitters with electroencephalogram and electromyogram electrodes were implanted for sleep recording. Animals were administered with caffeine alone (10 mg/kg) or in combination with zolpidem (10 mg/kg) or trazodone (20 mg/kg), or vehicle, in crossover experiments. Home polysomnography was performed in 12 healthy male volunteers in a randomised, placebo-controlled, 4-week crossover study. Subjects received placebo, caffeine (150 mg) or caffeine in combination with zolpidem (10 mg) or trazodone (100 mg). Subjective sleep effects in volunteers were assessed using the Leeds Sleep Evaluation Questionnaire. RESULTS: Caffeine caused a significant prolongation in objective SOL in rats and humans. This effect was sensitive to zolpidem and trazodone, both of which attenuated the caffeine-induced increase in SOL. Furthermore, both hypnotics restored the disruption in subjective measures of sleep onset caused by caffeine in volunteers.
CONCLUSIONS: This model therefore provides a promising paradigm in which we can study novel treatments for sleep disorders and an opportunity for direct comparison of results between rodents and humans.
Source : Psychopharmacology (Berl) 2007 vol.191 Issue 4 pp 943 - 950
Caffeine decreases vitamin D receptor protein expression and 1,25(OH)(2)D(3) stimulated alkaline phosphatase activity in human osteoblast cells
Rapuri, P. B.; Gallagher, J. C.; Nawaz, Z.
Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D(3) (1,25(OH)(2)D(3)) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)(2)D(3), VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)(2)D(3) mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10mM) on 1,25(OH)(2)D(3) induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)(2)D(3) induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)(2)D(3) induced VDR expression and at concentrations of 1 and 10mM, VDR expression was decreased by about 50-70%, respectively. In addition, the 1,25(OH)(2)D(3) induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)(2)D(3) stimulated VDR protein expression and 1,25(OH)(2)D(3) mediated actions in human osteoblast cells.
Source : J Steroid Biochem Mol Biol 2007 vol.103 (3-5), pp 368 - 371
Caffeine, mood and mental performance in everyday life
Rogers, P. J.
Studies on the influence of caffeine consumption on mood and cognitive function are reviewed. Although caffeine is often consumed for its psychostimulant effects, there is evidence that regular consumption does not have a net benefit on mood, alertness and work performance, and there may be adverse effects, such as dependency and an increase in anxiety. However, caffeine consumption may reduce the risk of age-related cognitive decline, possibly involving the neuroprotective functions of the adenosine system.
Source : BNF-Nutrition-Bulletin; 2007.(March), 32, supplement 'The influence of diet on cognitive function
Evaluation of neuronal phosphoproteins as effectors of caffeine and mediators of striatal adenosine A2A receptor signaling
Sahin, B.; Galdi, S.; Hendrick, J.; Greene, R. W.; Snyder, G. L.; Bibb, J. A.
Adenosine A(2A) receptors are predominantly expressed in the dendrites of enkephalin-positive gammaaminobutyric acidergic medium spiny neurons in the striatum. Evidence indicates that these receptors modulate striatal dopaminergic neurotransmission and regulate motor control, vigilance, alertness, and arousal. Although the physiological and behavioral correlates of adenosine A(2A) receptor signaling have been extensively studied using a combination of pharmacological and genetic tools, relatively little is known about the signal transduction pathways that mediate the diverse biological functions attributed to this adenosine receptor subtype. Using a candidate approach based on the coupling of these receptors to adenylate cyclase-activating G proteins, a number of membranal, cytosolic, and nuclear phosphoproteins regulated by PKA were evaluated as potential mediators of adenosine A(2A) receptor signaling in the striatum. Specifically, the adenosine A(2A) receptor agonist, CGS 21680, was used to determine whether the phosphorylation state of each of the following PKA targets is responsive to adenosine A(2A) receptor stimulation in this tissue: Ser40 of tyrosine hydroxylase, Ser9 of synapsin, Ser897 of the NR1 subunit of the N-methyl-d-aspartate-type glutamate receptor, Ser845 of the GluR1 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid-type glutamate receptor, Ser94 of spinophilin, Thr34 of the dopamine- and cAMP-regulated phosphoprotein, M(r) 32,000, Ser133 of the cAMP-response elementbinding protein, Thr286 of Ca(2+)/calmodulin-dependent protein kinase II, and Thr202/Tyr204 and Thr183/Tyr185 of the p44 and p42 isoforms, respectively, of mitogen-activated protein kinase. Although the substrates studied differed considerably in their responsiveness to selective adenosine A(2A) receptor activation, the phosphorylation state of all postsynaptic PKA targets was up-regulated in a time- and dosedependent manner by treatment with CGS 21680, whereas presynaptic PKA substrates were unresponsive to this agent, consistent with the postsynaptic localization of adenosine A(2A) receptors. Finally, the phosphorylation state of these proteins was further assessed in vivo by systemic administration of caffeine.
Source : Brain Res 2007 vol.1129 (1), pp 1 - 14
Coffee consumption and risk of coronary heart disease: a meta-analysis
Sofi, F.; Conti, A. A.; Gori, A. M.; Eliana-Luisi, M. L.; Casini, A.; Abbate, R.; Gensini, G. F.
During the past three decades the relationship between habitual coffee drinking and coronary heart disease (CHD) has been assessed in numerous studies, with conflicting results. The aim of this study was to systematically examine the data published on the association between habitual coffee consumption and risk of CHD. METHODS AND RESULTS: Thirteen case-control and 10 cohort studies were included. Case-control studies incorporated 9487 cases of CHD and 27,747 controls, and cohort studies included a total of 403,631 participants that were followed for between 3 and 44 years. The summary of odds ratios (OR) for the case-control studies showed statistically significant associations between coffee consumption and CHD for the highest intake group (>4 cups/day), OR 1.83 (95% CI 1.49-2.24; P<0.0001), and for the second highest category (3-4 cups/day), OR 1.33 (95% CI 1.04-1.71; P<0.0001), while no significant association emerged for low daily coffee intake (< or =2 cups/day), OR 1.03 (95% CI 0.87-1.21; P=0.45). The analysis of long-term follow-up cohort studies did not show any association between the consumption of coffee and CHD, with a relative risk (RR) of 1.16 (95% CI 0.95-1.41; P=0.14) for the highest category, and 1.05 (95% CI 0.90-1.22; P=0.57) and 1.04 (95%CI 0.90-1.19; P=0.60) for the second and third highest categories, respectively. These results did not differ substantially when controlling for region of origin, fatal and non-fatal events, year of publication, and number of years of follow-up.
CONCLUSIONS: Despite a significant association between high consumption of coffee and CHD reported among case-control studies, no significant association between daily coffee consumption and CHD emerged from long-term follow-up prospective cohort studies.
Source : Nutr Metab Cardiovasc Dis 2007 vol.17 (3), pp 209 - 223
Coffee intake and incidence of hypertension
Uiterwaal, C. S.; Verschuren, W. M.; Bueno-de-Mesquita, H. B.; Ocke, M.; Geleijnse, J. M.; Boshuizen, H.C.; Peeters, P. H.; Feskens, E. J.; Grobbee, D. E.
The long-term longitudinal evidence for a relation between coffee intake and hypertension is relatively scarce. OBJECTIVE: The objective was to assess whether coffee intake is associated with the incidence of hypertension. DESIGN: This study was conducted on a cohort of 2985 men and 3383 women who had a baseline visit and follow-up visits after 6 and 11 y. Baseline coffee intake was ascertained with questionnaires and categorized into 0, >0-3, >3-6, and >6 cups/d. Hypertension was defined as a mean systolic blood pressure (SBP) >/=140 mm Hg over both follow-up measurements, a mean diastolic blood pressure (DBP) >/=90 mm Hg over both follow-up measurements, or the use of antihypertensive medication at any follow-up measurement. RESULTS: Coffee abstainers at baseline had a lower risk of hypertension than did those with a coffee intake of >0-3 cups/d [odds ratio (OR): 0.54; 95% CI: 0.31, 0.92]. Women who drank >6 cups/d had a lower risk than did women who drank >0-3 cups/d (OR: 0.67; 95% CI: 0.46, 0.98). Subjects aged >/=39 y at baseline had 0.35 mm Hg (95% CI: -0.59, -0.11 mm Hg) lower SBP per cup intake/d and 0.11 mm Hg lower DBP (95% CI: -0.26, 0.03 mm Hg) than did those aged <39 y at baseline, although the difference in DBP was not statistically significant.
CONCLUSIONS: Coffee abstinence is associated with a lower hypertension risk than is low coffee consumption. An inverse U-shaped relation between coffee intake and risk of hypertension was observed in the women.
Source : Am J Clin Nutr 2007 vol.85 (3), pp 718 - 723
Caffeine protects Alzheimer\'s mice against cognitive impairment and reduces brain beta-amyloid production
Arendash, G. W.; Schleif, W.; Rezai-Zadeh, K.; Jackson, E. K.; Zacharia, L. C.; Cracchiolo, J. R.; Shippy, D.; Tan, J.
A recent epidemiological study suggested that higher caffeine intake over decades reduces the risk of Alzheimer's disease (AD). The present study sought to determine any long-term protective effects of dietary caffeine intake in a controlled longitudinal study involving AD transgenic mice. Caffeine (an adenosine receptor antagonist) was added to the drinking water of amyloid precursor protein, Swedish mutation (APPsw) transgenic (Tg) mice between 4 and 9 months of age, with behavioral testing done during the final 6 weeks of treatment. The average daily intake of caffeine per mouse (1.5 mg) was the human equivalent of 500 mg caffeine, the amount typically found in five cups of coffee per day. Across multiple cognitive tasks of spatial learning/reference memory, working memory, and recognition/identification, Tg mice given caffeine performed significantly better than Tg control mice and similar to non-transgenic controls. In both behaviorally-tested and aged Tg mice, long-term caffeine administration resulted in lower hippocampal beta-amyloid (Abeta) levels. Expression of both Presenilin 1 (PS1) and beta-secretase (BACE) was reduced in caffeine-treated Tg mice, indicating decreased Abeta production as a likely mechanism of caffeine's cognitive protection. The ability of caffeine to reduce Abeta production was confirmed in SweAPP N2a neuronal cultures, wherein concentration-dependent decreases in both Abeta1-40 and Abeta1-42 were observed. Although adenosine A(1) or A(2A) receptor densities in cortex or hippocampus were not affected by caffeine treatment, brain adenosine levels in Tg mice were restored back to normal by dietary caffeine and could be involved in the cognitive protection provided by caffeine. Our data demonstrate that moderate daily intake of caffeine may delay or reduce the risk of AD.
Source : Neuroscience 2007 vol.142 (4), pp 941 - 952
Effects of caffeine on electrophysiological and neuropsychological indices after sleep deprivation
Deslandes, A.; Ferreira, C.; Veiga, H.; Cagy, M.; Piedade, R.; Pompeu, F.; Ribeiro, P.
Caffeine is regarded as a central nervous system (CNS) stimulant. The goal of this study was to analyze electrophysiological, motor, cognitive and behavioral changes produced by caffeine ingestion after sleep deprivation. Ten subjects were evaluated after sleep deprivation, comparing the ingestion of either 400 mg of caffeine or placebo, in a double-blind randomized study. The variables analyzed were: quantitative EEG, the event-related potential (ERP-P300) and cognitive responses. The most significant quantitative EEG results, which were characterized by moment x treatment interactions, were seen in alpha and theta relative power variables. A significant decrease in relative alpha and theta was observed in the caffeine group after sleep deprivation. In relation to caffeine stimulant effects, there were no significant differences in the other parameters.
Source : Neuropsychobiology 2006 vol.54 (2), pp 126 - 133
Effect of caffeine on central auditory pathways: an evoked potential study
Dixit, A.; Vaney, N.; Tandon, O. P.
Caffeine is consumed in various forms like tea, coffee, chocolates and colas. The present study evaluated the effect of caffeine on auditory brainstem response (ABR), mid latency response (MLR) and slow vertex response (SVR) in 40 male volunteers. The recordings were done using a computerized evoked potential recorder by 10-20 electrode placement system. The subjects consumed 3mg/kg body weight of caffeine after 12h abstinence from caffeine in any form. The data obtained revealed that latencies of waves IV and V along with I-V interpeak interval of ABR decreased significantly. This was accompanied with significant increase in amplitude of wave V. MLR latencies and latency of P1 wave of SVR was significantly decreased following caffeine ingestion. The results indicated that caffeine improves transmission in the peripheral and central brain auditory pathways.
Source : Hear Res 2006 vol.220 (1-2), pp 61 - 66
Stress-related sleep disturbance and polysomnographic response to caffeine
Drake, C. L.; Jefferson, C.; Roehrs, T.; Roth, T.
To determine the sleep response to caffeine in individuals vulnerable to stress-related sleep disturbance as measured by polysomnography. PATIENTS AND METHODS: Eleven healthy individuals without insomnia scoring low (4 women, mean age=32.64+/-15.46 years) and 10 healthy individuals also without insomnia scoring high (6 women, mean age=34.20+/-13.73 years) on a measure of vulnerability to stress-related sleep disturbance were studied in a laboratory protocol. A moderate-low dose of caffeine (3 mg/kg) was administered 1h prior to lights-out and compared to a counterbalanced control night with each condition separated by 1 week. Standard polysomnographic measures were assessed (i.e. total sleep time, sleep efficiency, latency to persistent sleep, and sleep stage percentages) for both control and caffeine nights. RESULTS: There were no between-group differences in sleep on the control night. Importantly, individuals reporting vulnerability to stress-related sleep disturbance had significantly prolonged latency to persistent sleep in response to the caffeine challenge (interaction; P<0.05).
CONCLUSION: Normal sleepers with an identified vulnerability to stressinduced sleep disturbance exhibited greater objectively verifiable sleep-reactivity in response to a caffeine challenge compared to non-vulnerable individuals. These results suggest that the construct of individual differences in vulnerability to sleep disturbance applies to a pharmacological 'stressor' (i.e. caffeine) as well as to previously assessed stressors such as a first-night effect. This finding provides further support for generalized trait vulnerability by demonstrating a sleep disturbance to a wake-promoting pharmacological challenge in specific a priori identified individuals.
Source : Food Addit Contam 2006 vol.23 Issue 9 pp 902 – 909
Wingate performance and surface EMG frequency variables are not affected by caffeine ingestion
Greer, F.; Morales, J.; Coles, M.
The ergogenic effect of caffeine and its mechanism of action on short-term, high-intensity exercise are controversial. One proposed mechanism is caffeine's stimulatory effect on the central nervous system and thus, motor-unit excitation. The latter is non-invasively determined from surface electromyographic signal (EMG) frequency measures. The purpose of this study was to determine if power output and surface EMG frequency variables during high-intensity cycling were altered following caffeine ingestion. Eighteen recreationally active college males (mean +/- SD age, 21.5 +/- 1.8 y; height, 181.8 +/- 0.5 cm; body mass, 84.7 +/- 11.4 kg) performed the Wingate test (WG) after ingestion of gelatin capsules containing either placebo (PL; dextrose) or caffeine (CAFF; 5 mg/kg body mass). The trials were separated by 1 week and subjects were asked to withdraw from all caffeine-containing products for 48 h before each trial. From the resulting power-time records, peak power (PP; highest power output in 5 s), minimum power (MP; lowest power output in 5 s), and the percent decline in power (Pd) were calculated. Surface EMG records of the right vastus lateralis (VL) and the gastrocnemius (GA) muscles corresponding to the PP and MP periodswere collected and used to determine the integrated electromyogram (IEMG), the mean (MNPF), and the median (MDPF) of the signal's power spectrum. A 2-way repeated measures analysis of variance (ANOVA) (treatment x time) was conducted to determine the effect of caffeine on these variables across levels of time. Caffeine ingestion had no effect on PP (PL, 1049 +/- 192 W; CAFF, 1098 +/- 198 W), MP (PL, 762 +/- 104 W; CAFF, 802 +/- 124 W), or the Pd (PL, 47% +/- 8.9%; CAFF, 48.2% +/- 7.3%) compared with the placebo. For both muscles, MNPF and MDPF diminished significantly (p < 0.001) across time and to a similar degree in both the CAFF and PL trials. Regardless of muscle, CAFF had no effect on the percent change in IEMG from the first 5 s to the last 5 s. For both treatments, the GA displayed a significantly (p < 0.05) greater pre vs. post percent decline in the EMG signal amplitude compared with the VL. These results indicate that caffeine does not impact power output during a 30 s high-intensity cycling bout. Furthermore, these data suggest that caffeine does not impact the neuromuscular drive as indicated by the similar IEMG scores between treatments. Similarly, caffeine does not seem to impact the frequency content of the surface EMG signal and thus the nature of recruited motor units before and after the expression of fatigue. The lack of decline in the IEMG in the VL despite the decline in power output over the course of the WG suggests a peripheral as opposed to a neural mechanism of fatigue in this muscle. The significant difference in the pre vs. post percent decline in the GA IEMG score further supports this notion. The pre vs. post decline in the IEMG noted in the GA may suggest a fatigue-triggered change in pedaling mechanics that may promote dominance of knee extensors with less reliance on plantar flexors.
Source : Appl Physiol Nutr Metab 2006 vol.31 (5), pp 597 - 603
Caffeine intake, toxicity and dependence and lifetime risk for psychiatric and substance use disorders: an epidemiologic and co-twin control analysis
Kendler, K. S.; Myers, J.; Gardner, C.
Although caffeine is the most commonly used psychoactive substance and often produces symptoms of toxicity and dependence, little is known, especially in community samples, about the association between caffeine use, toxicity and dependence and risk for common psychiatric and substance use disorders. METHOD: Assessments of lifetime maximal caffeine use and symptoms of caffeine toxicity and dependence were available on over 3600 adult twins ascertained from the population-based Virginia Twin Registry. Lifetime histories of major depression (MD), generalized anxiety disorder (GAD) and panic disorder, alcohol dependence, adult antisocial behavior and cannabis and cocaine abuse/dependence were obtained at personal interview. Logistic regression analyses in the entire sample and within monozygotic (MZ) twin pairs were conducted in SAS. RESULTS: In the entire sample, measures of maximal caffeine use, heavy caffeine use, and caffeine-related toxicity and dependence were significantly and positively associated with all seven psychiatric and substance use disorders. However, within MZ twin pairs, controlling for genetic and family environmental factors, these associations, while positive, were all non-significant. These results were similar when excluding twins who denied regular caffeine use. CONCLUSIONS: Maximal lifetime caffeine intake and caffeine-associated toxicity and dependence are moderately associated with risk for a wide range of psychiatric and substance use disorders. Analyses of these relationships within MZ twin pairs suggest that most of the observed associations are not causal. Rather, familial factors, which are probably in part genetic, predispose to both caffeine intake, toxicity and dependence and the risk for a broad array of internalizing and externalizing disorders.
Source : Psychol Med 2006 vol.36 (12), pp 1717 - 1725
Trait-anger enhances effects of caffeine on psychomotor vigilance performance
Killgore, W. D.; Killgore, D. B.; Ganesan, G.; Krugler, A. L.; Kamimori, G. H.
This study examined the combined effects of caffeine and the personality attribute of trait-anger on the speed of psychomotor vigilance performance during sleep deprivation. 23 young adult soldiers (19 male) were administered the State-Trait Anger Expression Inventory-2 when well-rested. Participants were then sleep deprived for three consecutive nights (77 hours total) during which they completed repeated psychomotor vigilance testing. Half of the participants received four doses of oral caffeine (200 mg every 2 hr.; 800 mg total) each night, while the other half were administered a placebo. For the first night, higher scores on trait-anger, outward anger expression, and intensity of anger expression predicted better sustained overnight vigilance performance, but only for those volunteers receiving caffeine. These correlations were not significant for the subsequent nights. Findings suggest a possible synergistic effect between personality traits associated with arousal of the central nervous system and vigilance-promoting effects of caffeine.
Source : Percept Mot. Skills 2006 vol.103 (3), pp 883 - 886
The effects of chewing versus caffeine on alertness, cognitive performance and cardiac autonomic activity during sleep deprivation
Kohler, M.; Pavy, A.; van den Heuvel, C
Chewing has been shown to alleviate feelings of sleepiness and improve cognitive performance during the day. This study investigated the effect of chewing on alertness and cognitive performance across one night without sleep as well as the possible mediating role of cardiac autonomic activity. Fourteen adults participated in a randomized, counterbalanced protocol employing a chewing, placebo and caffeine condition. Participants completed tasks assessing psychomotor vigilance, tracking, grammatical reasoning, alertness and sleepiness each hour across the night. All participants received either placebo or caffeine (200 mg), while the chewing condition also chewed on a tasteless and odorless substance for 15 min each hour. Heart rate (HR), root mean square of the successive differences in R-R intervals on the ECG (RMSSD), and preejection period (PEP) were simultaneously recorded. Alertness and cognitive performance amongst the chewing condition did not differ or were in fact worse when compared with placebo. Similarly, measures of HR and RMSSD remained the same between these two conditions; however, PEP was reduced in the later part of the night in the chewing condition compared with a relative increase for placebo. Caffeine led to improved speed and accuracy on cognitive tasks and increased alertness when compared with chewing. Relative increases in RMSSD and reductions in HR were demonstrated following caffeine; however, no change in PEP was seen. Strong associations between cardiac parasympathetic activity and complex cognitive tasks, as well as between subjective alertness and simpler cognitive tasks, suggest a differential process mediating complex versus simple cognitive performance during sleep deprivation.
Source : J Sleep Res 2006 vol.15 Issue 4 pp 358 - 368
Acute exposure to caffeine decreases the anticonvulsant action of ethosuximide, but not that of clonazepam, phenobarbital and valproate against pentetrazole-induced seizures in mice
Luszczki, J. J.; Zuchora, M.; Sawicka, K. M.; Kozinska, J.; Czuczwar, S. J.
This study examines the effect of acute administration of caffeine sodium benzoate (CAF) on the anticonvulsant action of four conventional antiepileptic drugs (AEDs: clonazepam - CZP, ethosuximide - ETS, phenobarbital - PB and valproate - VPA) against pentetrazole (PTZ)-induced clonic seizures in mice. The results indicate that CAF at a dose of 92.4 mg/kg significantly reduced the threshold for PTZ-induced clonic seizures in mice from 69.5 to 51.7 mg/kg (p<0.05), being ineffective at lower doses of 69.3 and 46.2 mg/kg. Moreover, CAF at doses of and 92.4 mg/kg attenuated the protective action of ETS against PTZ-induced seizures, by increasing its median effective dose (ED50) from 127.7 to 182.3 (p<0.05), and 198.3 mg/kg (p<0.01), respectively. In this case, no pharmacokinetic changes in total brain ETS concentrations after systemic ip administration of CAF (at 92.4 mg/kg) were observed, indicating a pharmacodynamic nature of interaction between ETS and CAF in the PTZ-test in mice. In contrast, CAF (at a dose of 92.4 mg/kg reducing the threshold for PTZ-induced seizures) combined with other AEDs (CZP, PB and VPA) did not affect their anticonvulsant action in the PTZ test in mice. Moreover, CAF (92.4 mg/kg) did not alter significantly total brain concentrations of the remaining AEDs (CZP, PB and VPA). The evaluation of potential acute adverse effects produced by AEDs in combination with CAF revealed that neither CAF (up to 92.4 mg/kg) administered alone nor combined with the studied drugs (at doses corresponding to their ED(50) values in the PTZ-test) affected motor performance of animals in the chimney test. In conclusion, the acute exposure to CAF may diminish the antiseizure protection offered by ETS in epileptic patients. Therefore, patients treated with ETS should avoid CAF.
Source : Pharmacol Rep 2006 vol.58 (5), pp 652 - 659 (full text not available on-line)
Effects of chlorogenic acid and its metabolites on spontaneous locomotor activity in mice
Ohnishi, R.; Ito, H.; Iguchi, A.; Shinomiya, K.; Kamei, C.; Hatano, T.; Yoshida, T.
Chlorogenic acid (a polyphenol found in coffee) possessed weak caffeine-like psychostimulant activity on spontaneous locomotor activity in mice. In an evaluation of the effects of the major metabolites of chlorogenic acid (which were detected upon incubation with rat faeces and/or excreted in urine after oral administration to rats), caffeic and m-coumaric acids were found to be the principal active metabolites. Other metabolites contributed little to this caffeine-like psychostimulant activity.
Source : Bioscience 2006 vol.70 (10), pp 2560 - 2563
Is caffeine addictive? A review of the literature
Satel, S.
The common-sense use of the term addiction is that regular consumption is irresistible and that it creates problems. Caffeine use does not fit this profile. Its intake does no harm to the individual or to society and its users are not compelled to consume it. Though cessation of regular use may result in symptoms such as headache and lethargy, these are easily and reliably reversed by ingestion of caffeine. Some have argued that continued caffeine use is an attempt to suppress low grade withdrawal symptoms such as sleepiness and lethargy. In some moderate users, this is possible; however, in experimental contexts, the phenomenon is too inconsistent to constitute a reliably valid syndrome.
Source : Am J Drug Alcohol Abuse 2006 vol.32 (4), pp 493 - 502 (not available on-line)
CONSUMER SCIENCE
Beverage consumption in the US population
Storey, M. L.; Forshee, R. A.; Anderson, P. A.
Beverage consumption was examined across age, sex and race/ethnicity categories using the most current data available, the National Health and Nutrition Examination Survey 1999-2002. Beverage consumption that included fluid milk, fruit juices, regular and diet carbonated soft drinks, regular and diet fruit drinks/ades, coffee and tea was examined among white, African-American and Mexican-American persons in age groups 6-11 yr, 12-19 yr, 20-39 yr, 40-59 yr and >60 yr. Data from the National Health and Nutrition Examination Survey 1999-2002 were used in this study. Group means were estimated for the age group, sex and race/ethnicity subgroups. The probability that any of these group means were equal to one another was tested using statistical software. The data showed marked differences in beverage consumption depending on age, sex and race/ethnicity. In general, males consumed more beverages than did females. Specifically, white and Mexican-American persons of all ages consumed more milk than did African-American persons. On average, African-American males and females of all ages consumed significantly more fruit drinks/ades than did other race/ethnicity groups. In contrast, white persons consumed more carbonated soft drinks than did other race/ethnicity groups. These findings indicated that average beverage consumption varied depending on age, sex and race/ethnicity. Knowledge of differences in beverage consumption patterns is important for food and nutrition professionals and nutrition policymakers. Better understanding of the many factors that influence beverage consumption levels is needed.
Source : J Amer Diet Ass 2006 vol.106(12), pp 1992 - 2000