Abstracts
As the summer gets underway we want to take the opportunity to provide you with 12 recent scientific studies about coffee and some of the more than 230 compounds in it. Some of the studies reinforce the health benefits demonstrated in earlier studies we have sent you or which you may have found in prestigious journals. Others are more obscure, but nonetheless interesting.
Abstracts:
ATR-Chk1 pathway inhibition promotes apoptosis after UV treatment in primary human keratinocytes: potential basis for the UV protective effects of caffeine. Heffernan TP, Kawasumi M, Blasina A, Anderes K, Conney AH, Nghiem P. J Invest Dermatol. 2009 Jul;129(7):1805-15. See PDF
New approaches to prevent and reverse UV damage are needed to combat rising sunlight-induced skin cancer rates. Mouse studies have shown that oral or topical caffeine promotes elimination of UV-damaged keratinocytes through apoptosis and markedly inhibits subsequent skin cancer development. This potentially important therapeutic effect has not been studied in human skin cells. Here, we use primary human keratinocytes to examine which of several caffeine effects mediates this process. In these cells, caffeine more than doubled apoptosis after 75 mJ cm(-2) of ultraviolet light B (UVB). Selectively targeting two of caffeine's known effects did not alter UVB-induced apoptosis: inhibition of ataxia-telangiectasia mutated and augmentation of cyclic AMP levels. In contrast, siRNA against ataxia-telangiectasia and Rad3-related (ATR) doubled apoptosis after UV through a p53-independent mechanism. Caffeine did not further augment apoptosis after UVB in cells in which ATR had been specifically depleted, suggesting that a key target of caffeine in this effect is ATR. Inhibition of a central ATR target, checkpoint kinase 1 (Chk1), through siRNA or a new and highly specific inhibitor (PF610666) also augmented UVB-induced apoptosis. These data suggest that a relevant target of caffeine is the ATR-Chk1 pathway and that inhibiting ATR or Chk1 might have promise in preventing or reversing UV damage.
Review and comment on the above study in the same journal: UVB and caffeine: inhibiting the DNA damage response to protect against the adverse effects of UVB. Kerzendorfer C, O'Driscoll M. J Invest Dermatol.
2009 Jul;129(7):1611-3.
The incidence of sunlight-induced skin cancer is increasing. Mouse studies indicate that caffeine, administered orally or topically, promotes apoptosis of UVB-irradiated keratinocytes. In this issue, Heffernan and colleagues identify the pathway targeted by caffeine and suggest that inhibition of this DNA damage response may offer a viable therapeutic option for nonmelanoma skin cancer. This potentially represents an important protective or therapeutic option from the most unlikely of sources: your daily coffee.
Effect of coffee and green tea consumption on the risk of liver cancer: cohort analysis by hepatitis virus infection status. Inoue M, Kurahashi N, Iwasaki M, et al; Japan Public Health Center-Based Prospective Study Group. Cancer Epidemiol Biomarkers Prev. 2009 Jun;18(6):1746-53.
In spite of their anticarcinogenic potential, the effect of coffee and green tea consumption on the risk of liver cancer has not been clarified prospectively in consideration of hepatitis C (HCV) and B virus (HBV) infection. We examined whether coffee and green tea consumption was associated with a reduced risk of liver cancer by hepatitis virus infection status in the Japan Public Health Center-Based Prospective Study Cohort II. A total of 18,815 subjects ages 40 to 69 years participating in a questionnaire and health checkup survey in 1993 to 1994 were followed for the incidence of liver cancer through 2006. A total of 110 cases of liver cancer were newly documented. Hazard ratios for coffee and green tea consumption categories were calculated with a Cox proportional hazards model. Compared with almost never drinkers, increased coffee consumption was associated with a reduced risk of liver cancer in all subjects (hazard ratio for <1, 1-2, and >or=3 cups/d; P(trend) = 0.67, 0.49, 0.54, and 0.025). A similar risk tendency was observed in those with either or both HCV and HBV infection. In contrast, no association was observed between green tea consumption and the risk of liver cancer in all subjects. Our results suggest that coffee consumption may reduce the risk of liver cancer regardless of HCV and HBV infection status, whereas green tea may not reduce this risk.
Good news for coffee addicts. Lee TH. Harvard Bus Rev. 2009 Jun;87(6):22, 112. See PDF
Whether it's a basic Mr. Coffee or a gadget that sports a snazzy device for grinding beans on demand, the office coffee machine offers a place for serendipitous encounters that can improve the social aspect of work and generate new ideas. What's more, a steaming cup of joe may be as good for your health as it is for the bottom line, says Lee, a professor of medicine at Harvard Medical School and the CEO of Partners Community HealthCare. Fears of coffee's carcinogenic effects now appear to be unfounded, and, in fact, the brew might even protect against some types of cancer. What's more, coffee may guard against Alzheimer's disease and other forms of dementia and somehow soften the blow of a heart attack. Of course, its role as a pick-me-up is well known. So there's no need to take your coffee with a dollop of guilt, especially if you ease up on the sugar, cream, double chocolate, and whipped-cream topping.
Anti-cariogenic effects of polyphenols from plant stimulant beverages (cocoa, coffee, tea). Ferrazzano GF, Amato I, Ingenito A, et al. Fitoterapia. 2009 Jul;80(5):255-62.
Polyphenols occurring in cocoa, coffee and tea can have a role in the prevention of cariogenic processes, due to their antibacterial action. Cocoa polyphenol pentamers significantly reduce biofilm formation and acid production by Streptococcus mutans and S. sanguinis. In the same way, trigonelline, caffeine and chlorogenic acid occurring in green and roasted coffee interfere with S. mutans adsorption to saliva-coated hydroxyapatite beads. Studies carried out on green, oolong and black tea indicate that tea polyphenols exert an anti-caries effect via an anti-microbial mode-of-action, and galloyl esters of (-)-epicatechin, (-)-epigallocatechin and (-)-gallocatechin show increasing antibacterial activities. The anti-cariogenic effects against alpha-haemolytic streptococci showed by polyphenols from cocoa, coffee, and tea suggest further studies to a possible application of these beverages in the prevention of pathogenesis of dental caries.
Feasibility of ethanol production from coffee husks. Gouvea BM, Torres C, Franca AS, et al. Biotechnol Lett. 2009 May 23.
The objective of this work was to evaluate the feasibility of ethanol production by fermentation of coffee husks by Saccharomyces cerevisiae. Batch fermentation studies were performed employing whole and ground coffee husks, and aqueous extract from ground coffee husks. It was observed that fermentation yield decreased with an increase in yeast concentration. The best results were obtained for the following conditions: whole coffee husks, 3 g yeast/l substrate, temperature of 30 degrees C. Under these conditions ethanol production was 8.49 +/- 0.29 g/100 g dry basis (13.6 +/- 0.5 g ethanol/l), a satisfactory value in comparison to literature data for other residues such as corn stalks, barley straw and hydrolyzed wheat stillage (5-11 g ethanol/l). Such results indicate that coffee husks present excellent potential for residue-based ethanol production.
Effect of caffeine on quadriceps muscle pain during acute cycling exercise in low versus high caffeine consumers. Gliottoni RC, Meyers JR, Arngrimsson SA, Broglio SP, Motl RW. Int J Sport Nutr Exerc Metab. 2009 Apr;19(2):150-61.
This experiment examined the effect of a moderate dose of caffeine on quadriceps muscle pain during a bout of high-intensity cycling in low- versus high-caffeine-consuming males. College-age men who were low (< or =100 mg/day; n = 12) or high (> or =400 mg/day; n = 13) habitual caffeine consumers ingested caffeine (5 mg/kg body weight) or a placebo in a counterbalanced order and 1 hr later completed 30 min of cycle ergometry at 75-77% of peak oxygen consumption. Perceptions of quadriceps muscle pain, as well as oxygen consumption, heart rate, and work rate, were recorded during both bouts of exercise. Caffeine ingestion resulted in a statistically significant and moderate reduction in quadriceps muscle-pain-intensity ratings during the 30-min bout of high-intensity cycle ergometry compared with placebo ingestion in both low (d = -0.42) and high (d = -0.55) caffeine consumers. The results suggest that caffeine ingestion is associated with a moderate hypoalgesic effect during high-intensity cycling in college-age men who are low or high habitual caffeine consumers, but future work should consider better defining and differentiating pain and effort when examining the effects of caffeine during acute exercise.
Coffee consumption and mortality after acute myocardial infarction: the Stockholm Heart Epidemiology Program. Mukamal KJ, Hallqvist J, Hammar N, Ljung R, Gémes K, Ahlbom A, Ahnve S, Janszky I. Am Heart J. 2009 Mar;157(3):495-501.
BACKGROUND: Cohort studies have suggested little effect of coffee consumption on risk of acute myocardial infarction. The effect of coffee consumption on prognosis after myocardial infarction is uncertain. METHODS: In a population-based inception cohort study, we followed 1,369 patients hospitalized with a confirmed first acute myocardial infarction between 1992 and 1994 in Stockholm County, Sweden, as part of the Stockholm Heart Epidemiology Program. Participants reported usual coffee consumption over the preceding year with a standardized questionnaire distributed during hospitalization and underwent a health examination 3 months after discharge. Participants were followed for hospitalizations and mortality with national registers through November 2001. RESULTS: A total of 289 patients died during follow-up. Compared with intake of <1 cup per day, coffee consumption was inversely associated with mortality, with multivariable-adjusted hazard ratios of 0.68 (95% confidence interval [CI] 0.45-1.02) for 1 to <3 cups, 0.56 (95% CI 0.37-0.85) for 3 to <5 cups, 0.52 (95% CI 0.34-0.83) for 5 to <7 cups, and 0.58 (95% CI 0.34-0.98) for > or =7 cups per day (P trend .06). Coffee intake was not associated with hospitalization for congestive heart failure or stroke. Candidate lipid and inflammatory biomarkers did not appear to account for the observed inverse association with mortality. CONCLUSIONS: Self-reported coffee consumption at the time of hospitalization for myocardial infarction was inversely associated with subsequent postinfarction mortality in this population with broad coffee intake. If confirmed in other settings, identification of relevant mechanisms could lead to an improved prognosis for survivors of acute myocardial infarction.
Midlife coffee and tea drinking and the risk of late-life dementia: a population-based CAIDE study. Eskelinen MH, Ngandu T, Tuomilehto J, Soininen H, Kivipelto M. J Alzheimers Dis. 2009 Jan;16(1):85-91. See PDF
Caffeine stimulates central nervous system on a short term. However, the long-term impact of caffeine on cognition remains unclear. We aimed to study the association between coffee and/or tea consumption at midlife and dementia/Alzheimer's disease (AD) risk in late-life. Participants of the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study were randomly selected from the survivors of a population-based cohorts previously surveyed within the North Karelia Project and the FINMONICA study in 1972, 1977, 1982 or 1987 (midlife visit). After an average follow-up of 21 years, 1409 individuals (71%) aged 65 to 79 completed the re-examination in 1998. A total of 61 cases were identified as demented (48 with AD). Coffee drinkers at midlife had lower risk of dementia and AD later in life compared with those drinking no or only little coffee adjusted for demographic, lifestyle and vascular factors, apolipoprotein E epsilon4 allele and depressive symptoms. The lowest risk (65% decreased) was found in people who drank 3-5 cups per day. Tea drinking was relatively uncommon and was not associated with dementia/AD. Coffee drinking at midlife is associated with a decreased risk of dementia/AD later in life. This finding might open possibilities for prevention of dementia/AD.
Coffee drinking and endometrial cancer risk: a metaanalysis of observational studies. Bravi F, Scotti L, Bosetti C, Gallus S, Negri E, La
Vecchia C, Tavani A. Am J Obstet Gynecol. 2009 Feb;200(2):130-5.
We conducted a metaanalysis of published studies on the relation between coffee drinking and endometrial cancer risk, which included 2 cohort (201 cases) and 7 case-control studies (2409 cases). The summary relative risk (RR) for coffee drinkers vs nondrinkers was 0.80 (95% confidence interval [CI], 0.68-0.94), with significant heterogeneity between studies. Compared with nondrinkers, the summary RR was 0.87 (95% CI, 0.78-0.97) for low-to-moderate coffee drinkers and 0.64 (95% CI, 0.48-0.86) for heavy coffee drinkers. The summary RR for an increase of 1 cup/d was 0.93 (95% CI, 0.89-0.97), which suggests an inverse relation between coffee and endometrial cancer. However, the causality must be confirmed.
Coffee intake, smoking, and pulmonary function in the Atherosclerosis Risk in Communities Study. Nettleton JA, Follis JL, Schabath MB. Am J Epidemiol. 2009 Jun 15;169(12):1445-53.
Coffee contains polyphenolic antioxidants and caffeine, which may favorably affect pulmonary function. Therefore, the authors studied cross-sectional associations (1987-1989) between coffee intake and pulmonary function in the Atherosclerosis Risk in Communities Study, a population-based cohort study (analytic sample = 10,658). They also conducted analyses stratified by smoking status, since smoking is a strong risk factor for respiratory disease and could influence the effects of caffeine and antioxidants. Self-reported coffee intake was categorized as rare/never, <7 cups/week, 1 cup/day, 2-3 cups/day, and >or=4 cups/day. Pulmonary function was characterized by the spirometric measures forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV(1)). After adjustment for demographic factors, lifestyle characteristics, and dietary factors, pulmonary function values increased across increasing categories of coffee consumption in never and former smokers but not in current smokers. In never or former smokers who consumed >or=4 cups of coffee daily, FVC and FEV(1) were 2%-3% greater than in never or former smokers who rarely/never consumed coffee (P(trend) values: in never smokers, 0.04 for FVC and 0.07 for FEV(1); in former smokers, <0.001 for FVC and <0.001 for FEV(1)). These data show a possible beneficial effect of coffee (or a coffee ingredient) on pulmonary function, but it appears to be limited to nonsmokers.
Coffee consumption and risk of stroke in women. Lopez-Garcia E, Rodriguez-Artalejo F, Rexrode KM, et al. Circulation. 2009 Mar 3;119(8):1116-23. See PDF
BACKGROUND: Data on the association between coffee consumption and risk of stroke are sparse. We assessed the association between coffee consumption and the risk of stroke over 24 years of follow-up in women. METHODS AND RESULTS: We analyzed data from a prospective cohort of 83,076 women in the Nurses' Health Study without history of stroke, coronary heart disease, diabetes, or cancer at baseline. Coffee consumption was assessed first in 1980 and then repeatedly every 2 to 4 years, with follow-up through 2004. We documented 2280 strokes, of which 426 were hemorrhagic, 1224 were ischemic, and 630 were undetermined. In multivariable Cox regression models with adjustment for age, smoking status, body mass index, physical activity, alcohol intake, menopausal status, hormone replacement therapy, aspirin use, and dietary factors, the relative risks (RRs) of stroke across categories of coffee consumption (<1 cup per month, 1 per month to 4 per week, 5 to 7 per week, 2 to 3 per day, and >or=4 per day) were 1, 0.98 (95% CI, 0.84 to 1.15), 0.88 (95% CI, 0.77 to 1.02), 0.81 (95% CI, 0.70 to 0.95), and 0.80 (95% CI, 0.64 to 0.98) (P for trend=0.003). After further adjustment for high blood pressure, hypercholesterolemia, and type 2 diabetes, the inverse association remained significant. The association was stronger among never and past smokers (RR for >or=4 cups a day versus <1 cup a month, 0.57; 95% CI, 0.39 to 0.84) than among current smokers (RR for >or=4 cups a day versus <1 cup a month, 0.97; 95% CI, 0.63 to 1.48). Other drinks containing caffeine such as tea and caffeinated soft drinks were not associated with stroke. Decaffeinated coffee was associated with a trend toward lower risk of stroke after adjustment for caffeinated coffee consumption (RR for >or=2 cups a day versus <1 cup a month, 0.89; 95% CI, 0.73 to 1.08; P for trend=0.05). CONCLUSIONS: Long-term coffee consumption was not associated with an increased risk of stroke in women. In contrast, our data suggest that coffee consumption may modestly reduce risk of stroke.
Effect of caffeine on the expression of cytochrome P450 1A2, adenosine A2A receptor and dopamine transporter in control and 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropyridine treated mouse striatum. Singh S, Singh K, Gupta SP, et al. Brain Res. 2009 Jun 8.
Parkinson's disease (PD) is a progressive neurodegenerative disorder, characterized by the selective loss of dopaminergic neurons of the nigrostriatal pathway. Epidemiological studies have shown an inverse relationship between coffee consumption and susceptibility to PD. Cytochrome P450 1A2 (CYP1A2) is involved in caffeine metabolism and its clearance. Caffeine, on the other hand, antagonizes adenosine A(2A) receptor and regulates dopamine signaling through dopamine transporter (DAT). The present study was undertaken to investigate the expression of CYP1A2, adenosine A(2A) receptor and DAT in mouse striatum and to assess their levels in 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropryridine (MPTP) treated mouse striatum with and without caffeine treatment. The animals were treated intraperitoneally daily with caffeine (20 mg/kg) for 8 weeks, followed by MPTP (20 mg/kg)+ caffeine (20 mg/kg) for 4 weeks or vice versa, along with respective controls. Tyrosine hydroxylase immunoreactivity, levels of dopamine and 1-methyl 4-phenylpyridinium ion (MPP(+)), expressions of CYP1A2, adenosine A(2A) receptor and DAT and CYP1A2 catalytic activity were measured in control and treated mouse brain. Caffeine partially protected MPTP-induced neurodegenerative changes and modulated MPTP-mediated alterations in the expression and catalytic activity of CYP1A2, expression of adenosine A(2A) receptor and DAT. The results demonstrate that caffeine alters the striatal CYP1A2, adenosine A(2A) receptor and DAT expressions in mice exposed to MPTP.
Abstracts:
ATR-Chk1 pathway inhibition promotes apoptosis after UV treatment in primary human keratinocytes: potential basis for the UV protective effects of caffeine. Heffernan TP, Kawasumi M, Blasina A, Anderes K, Conney AH, Nghiem P. J Invest Dermatol. 2009 Jul;129(7):1805-15. See PDF
New approaches to prevent and reverse UV damage are needed to combat rising sunlight-induced skin cancer rates. Mouse studies have shown that oral or topical caffeine promotes elimination of UV-damaged keratinocytes through apoptosis and markedly inhibits subsequent skin cancer development. This potentially important therapeutic effect has not been studied in human skin cells. Here, we use primary human keratinocytes to examine which of several caffeine effects mediates this process. In these cells, caffeine more than doubled apoptosis after 75 mJ cm(-2) of ultraviolet light B (UVB). Selectively targeting two of caffeine's known effects did not alter UVB-induced apoptosis: inhibition of ataxia-telangiectasia mutated and augmentation of cyclic AMP levels. In contrast, siRNA against ataxia-telangiectasia and Rad3-related (ATR) doubled apoptosis after UV through a p53-independent mechanism. Caffeine did not further augment apoptosis after UVB in cells in which ATR had been specifically depleted, suggesting that a key target of caffeine in this effect is ATR. Inhibition of a central ATR target, checkpoint kinase 1 (Chk1), through siRNA or a new and highly specific inhibitor (PF610666) also augmented UVB-induced apoptosis. These data suggest that a relevant target of caffeine is the ATR-Chk1 pathway and that inhibiting ATR or Chk1 might have promise in preventing or reversing UV damage.
Review and comment on the above study in the same journal: UVB and caffeine: inhibiting the DNA damage response to protect against the adverse effects of UVB. Kerzendorfer C, O'Driscoll M. J Invest Dermatol.
2009 Jul;129(7):1611-3.
The incidence of sunlight-induced skin cancer is increasing. Mouse studies indicate that caffeine, administered orally or topically, promotes apoptosis of UVB-irradiated keratinocytes. In this issue, Heffernan and colleagues identify the pathway targeted by caffeine and suggest that inhibition of this DNA damage response may offer a viable therapeutic option for nonmelanoma skin cancer. This potentially represents an important protective or therapeutic option from the most unlikely of sources: your daily coffee.
Effect of coffee and green tea consumption on the risk of liver cancer: cohort analysis by hepatitis virus infection status. Inoue M, Kurahashi N, Iwasaki M, et al; Japan Public Health Center-Based Prospective Study Group. Cancer Epidemiol Biomarkers Prev. 2009 Jun;18(6):1746-53.
In spite of their anticarcinogenic potential, the effect of coffee and green tea consumption on the risk of liver cancer has not been clarified prospectively in consideration of hepatitis C (HCV) and B virus (HBV) infection. We examined whether coffee and green tea consumption was associated with a reduced risk of liver cancer by hepatitis virus infection status in the Japan Public Health Center-Based Prospective Study Cohort II. A total of 18,815 subjects ages 40 to 69 years participating in a questionnaire and health checkup survey in 1993 to 1994 were followed for the incidence of liver cancer through 2006. A total of 110 cases of liver cancer were newly documented. Hazard ratios for coffee and green tea consumption categories were calculated with a Cox proportional hazards model. Compared with almost never drinkers, increased coffee consumption was associated with a reduced risk of liver cancer in all subjects (hazard ratio for <1, 1-2, and >or=3 cups/d; P(trend) = 0.67, 0.49, 0.54, and 0.025). A similar risk tendency was observed in those with either or both HCV and HBV infection. In contrast, no association was observed between green tea consumption and the risk of liver cancer in all subjects. Our results suggest that coffee consumption may reduce the risk of liver cancer regardless of HCV and HBV infection status, whereas green tea may not reduce this risk.
Good news for coffee addicts. Lee TH. Harvard Bus Rev. 2009 Jun;87(6):22, 112. See PDF
Whether it's a basic Mr. Coffee or a gadget that sports a snazzy device for grinding beans on demand, the office coffee machine offers a place for serendipitous encounters that can improve the social aspect of work and generate new ideas. What's more, a steaming cup of joe may be as good for your health as it is for the bottom line, says Lee, a professor of medicine at Harvard Medical School and the CEO of Partners Community HealthCare. Fears of coffee's carcinogenic effects now appear to be unfounded, and, in fact, the brew might even protect against some types of cancer. What's more, coffee may guard against Alzheimer's disease and other forms of dementia and somehow soften the blow of a heart attack. Of course, its role as a pick-me-up is well known. So there's no need to take your coffee with a dollop of guilt, especially if you ease up on the sugar, cream, double chocolate, and whipped-cream topping.
Anti-cariogenic effects of polyphenols from plant stimulant beverages (cocoa, coffee, tea). Ferrazzano GF, Amato I, Ingenito A, et al. Fitoterapia. 2009 Jul;80(5):255-62.
Polyphenols occurring in cocoa, coffee and tea can have a role in the prevention of cariogenic processes, due to their antibacterial action. Cocoa polyphenol pentamers significantly reduce biofilm formation and acid production by Streptococcus mutans and S. sanguinis. In the same way, trigonelline, caffeine and chlorogenic acid occurring in green and roasted coffee interfere with S. mutans adsorption to saliva-coated hydroxyapatite beads. Studies carried out on green, oolong and black tea indicate that tea polyphenols exert an anti-caries effect via an anti-microbial mode-of-action, and galloyl esters of (-)-epicatechin, (-)-epigallocatechin and (-)-gallocatechin show increasing antibacterial activities. The anti-cariogenic effects against alpha-haemolytic streptococci showed by polyphenols from cocoa, coffee, and tea suggest further studies to a possible application of these beverages in the prevention of pathogenesis of dental caries.
Feasibility of ethanol production from coffee husks. Gouvea BM, Torres C, Franca AS, et al. Biotechnol Lett. 2009 May 23.
The objective of this work was to evaluate the feasibility of ethanol production by fermentation of coffee husks by Saccharomyces cerevisiae. Batch fermentation studies were performed employing whole and ground coffee husks, and aqueous extract from ground coffee husks. It was observed that fermentation yield decreased with an increase in yeast concentration. The best results were obtained for the following conditions: whole coffee husks, 3 g yeast/l substrate, temperature of 30 degrees C. Under these conditions ethanol production was 8.49 +/- 0.29 g/100 g dry basis (13.6 +/- 0.5 g ethanol/l), a satisfactory value in comparison to literature data for other residues such as corn stalks, barley straw and hydrolyzed wheat stillage (5-11 g ethanol/l). Such results indicate that coffee husks present excellent potential for residue-based ethanol production.
Effect of caffeine on quadriceps muscle pain during acute cycling exercise in low versus high caffeine consumers. Gliottoni RC, Meyers JR, Arngrimsson SA, Broglio SP, Motl RW. Int J Sport Nutr Exerc Metab. 2009 Apr;19(2):150-61.
This experiment examined the effect of a moderate dose of caffeine on quadriceps muscle pain during a bout of high-intensity cycling in low- versus high-caffeine-consuming males. College-age men who were low (< or =100 mg/day; n = 12) or high (> or =400 mg/day; n = 13) habitual caffeine consumers ingested caffeine (5 mg/kg body weight) or a placebo in a counterbalanced order and 1 hr later completed 30 min of cycle ergometry at 75-77% of peak oxygen consumption. Perceptions of quadriceps muscle pain, as well as oxygen consumption, heart rate, and work rate, were recorded during both bouts of exercise. Caffeine ingestion resulted in a statistically significant and moderate reduction in quadriceps muscle-pain-intensity ratings during the 30-min bout of high-intensity cycle ergometry compared with placebo ingestion in both low (d = -0.42) and high (d = -0.55) caffeine consumers. The results suggest that caffeine ingestion is associated with a moderate hypoalgesic effect during high-intensity cycling in college-age men who are low or high habitual caffeine consumers, but future work should consider better defining and differentiating pain and effort when examining the effects of caffeine during acute exercise.
Coffee consumption and mortality after acute myocardial infarction: the Stockholm Heart Epidemiology Program. Mukamal KJ, Hallqvist J, Hammar N, Ljung R, Gémes K, Ahlbom A, Ahnve S, Janszky I. Am Heart J. 2009 Mar;157(3):495-501.
BACKGROUND: Cohort studies have suggested little effect of coffee consumption on risk of acute myocardial infarction. The effect of coffee consumption on prognosis after myocardial infarction is uncertain. METHODS: In a population-based inception cohort study, we followed 1,369 patients hospitalized with a confirmed first acute myocardial infarction between 1992 and 1994 in Stockholm County, Sweden, as part of the Stockholm Heart Epidemiology Program. Participants reported usual coffee consumption over the preceding year with a standardized questionnaire distributed during hospitalization and underwent a health examination 3 months after discharge. Participants were followed for hospitalizations and mortality with national registers through November 2001. RESULTS: A total of 289 patients died during follow-up. Compared with intake of <1 cup per day, coffee consumption was inversely associated with mortality, with multivariable-adjusted hazard ratios of 0.68 (95% confidence interval [CI] 0.45-1.02) for 1 to <3 cups, 0.56 (95% CI 0.37-0.85) for 3 to <5 cups, 0.52 (95% CI 0.34-0.83) for 5 to <7 cups, and 0.58 (95% CI 0.34-0.98) for > or =7 cups per day (P trend .06). Coffee intake was not associated with hospitalization for congestive heart failure or stroke. Candidate lipid and inflammatory biomarkers did not appear to account for the observed inverse association with mortality. CONCLUSIONS: Self-reported coffee consumption at the time of hospitalization for myocardial infarction was inversely associated with subsequent postinfarction mortality in this population with broad coffee intake. If confirmed in other settings, identification of relevant mechanisms could lead to an improved prognosis for survivors of acute myocardial infarction.
Midlife coffee and tea drinking and the risk of late-life dementia: a population-based CAIDE study. Eskelinen MH, Ngandu T, Tuomilehto J, Soininen H, Kivipelto M. J Alzheimers Dis. 2009 Jan;16(1):85-91. See PDF
Caffeine stimulates central nervous system on a short term. However, the long-term impact of caffeine on cognition remains unclear. We aimed to study the association between coffee and/or tea consumption at midlife and dementia/Alzheimer's disease (AD) risk in late-life. Participants of the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study were randomly selected from the survivors of a population-based cohorts previously surveyed within the North Karelia Project and the FINMONICA study in 1972, 1977, 1982 or 1987 (midlife visit). After an average follow-up of 21 years, 1409 individuals (71%) aged 65 to 79 completed the re-examination in 1998. A total of 61 cases were identified as demented (48 with AD). Coffee drinkers at midlife had lower risk of dementia and AD later in life compared with those drinking no or only little coffee adjusted for demographic, lifestyle and vascular factors, apolipoprotein E epsilon4 allele and depressive symptoms. The lowest risk (65% decreased) was found in people who drank 3-5 cups per day. Tea drinking was relatively uncommon and was not associated with dementia/AD. Coffee drinking at midlife is associated with a decreased risk of dementia/AD later in life. This finding might open possibilities for prevention of dementia/AD.
Coffee drinking and endometrial cancer risk: a metaanalysis of observational studies. Bravi F, Scotti L, Bosetti C, Gallus S, Negri E, La
Vecchia C, Tavani A. Am J Obstet Gynecol. 2009 Feb;200(2):130-5.
We conducted a metaanalysis of published studies on the relation between coffee drinking and endometrial cancer risk, which included 2 cohort (201 cases) and 7 case-control studies (2409 cases). The summary relative risk (RR) for coffee drinkers vs nondrinkers was 0.80 (95% confidence interval [CI], 0.68-0.94), with significant heterogeneity between studies. Compared with nondrinkers, the summary RR was 0.87 (95% CI, 0.78-0.97) for low-to-moderate coffee drinkers and 0.64 (95% CI, 0.48-0.86) for heavy coffee drinkers. The summary RR for an increase of 1 cup/d was 0.93 (95% CI, 0.89-0.97), which suggests an inverse relation between coffee and endometrial cancer. However, the causality must be confirmed.
Coffee intake, smoking, and pulmonary function in the Atherosclerosis Risk in Communities Study. Nettleton JA, Follis JL, Schabath MB. Am J Epidemiol. 2009 Jun 15;169(12):1445-53.
Coffee contains polyphenolic antioxidants and caffeine, which may favorably affect pulmonary function. Therefore, the authors studied cross-sectional associations (1987-1989) between coffee intake and pulmonary function in the Atherosclerosis Risk in Communities Study, a population-based cohort study (analytic sample = 10,658). They also conducted analyses stratified by smoking status, since smoking is a strong risk factor for respiratory disease and could influence the effects of caffeine and antioxidants. Self-reported coffee intake was categorized as rare/never, <7 cups/week, 1 cup/day, 2-3 cups/day, and >or=4 cups/day. Pulmonary function was characterized by the spirometric measures forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV(1)). After adjustment for demographic factors, lifestyle characteristics, and dietary factors, pulmonary function values increased across increasing categories of coffee consumption in never and former smokers but not in current smokers. In never or former smokers who consumed >or=4 cups of coffee daily, FVC and FEV(1) were 2%-3% greater than in never or former smokers who rarely/never consumed coffee (P(trend) values: in never smokers, 0.04 for FVC and 0.07 for FEV(1); in former smokers, <0.001 for FVC and <0.001 for FEV(1)). These data show a possible beneficial effect of coffee (or a coffee ingredient) on pulmonary function, but it appears to be limited to nonsmokers.
Coffee consumption and risk of stroke in women. Lopez-Garcia E, Rodriguez-Artalejo F, Rexrode KM, et al. Circulation. 2009 Mar 3;119(8):1116-23. See PDF
BACKGROUND: Data on the association between coffee consumption and risk of stroke are sparse. We assessed the association between coffee consumption and the risk of stroke over 24 years of follow-up in women. METHODS AND RESULTS: We analyzed data from a prospective cohort of 83,076 women in the Nurses' Health Study without history of stroke, coronary heart disease, diabetes, or cancer at baseline. Coffee consumption was assessed first in 1980 and then repeatedly every 2 to 4 years, with follow-up through 2004. We documented 2280 strokes, of which 426 were hemorrhagic, 1224 were ischemic, and 630 were undetermined. In multivariable Cox regression models with adjustment for age, smoking status, body mass index, physical activity, alcohol intake, menopausal status, hormone replacement therapy, aspirin use, and dietary factors, the relative risks (RRs) of stroke across categories of coffee consumption (<1 cup per month, 1 per month to 4 per week, 5 to 7 per week, 2 to 3 per day, and >or=4 per day) were 1, 0.98 (95% CI, 0.84 to 1.15), 0.88 (95% CI, 0.77 to 1.02), 0.81 (95% CI, 0.70 to 0.95), and 0.80 (95% CI, 0.64 to 0.98) (P for trend=0.003). After further adjustment for high blood pressure, hypercholesterolemia, and type 2 diabetes, the inverse association remained significant. The association was stronger among never and past smokers (RR for >or=4 cups a day versus <1 cup a month, 0.57; 95% CI, 0.39 to 0.84) than among current smokers (RR for >or=4 cups a day versus <1 cup a month, 0.97; 95% CI, 0.63 to 1.48). Other drinks containing caffeine such as tea and caffeinated soft drinks were not associated with stroke. Decaffeinated coffee was associated with a trend toward lower risk of stroke after adjustment for caffeinated coffee consumption (RR for >or=2 cups a day versus <1 cup a month, 0.89; 95% CI, 0.73 to 1.08; P for trend=0.05). CONCLUSIONS: Long-term coffee consumption was not associated with an increased risk of stroke in women. In contrast, our data suggest that coffee consumption may modestly reduce risk of stroke.
Effect of caffeine on the expression of cytochrome P450 1A2, adenosine A2A receptor and dopamine transporter in control and 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropyridine treated mouse striatum. Singh S, Singh K, Gupta SP, et al. Brain Res. 2009 Jun 8.
Parkinson's disease (PD) is a progressive neurodegenerative disorder, characterized by the selective loss of dopaminergic neurons of the nigrostriatal pathway. Epidemiological studies have shown an inverse relationship between coffee consumption and susceptibility to PD. Cytochrome P450 1A2 (CYP1A2) is involved in caffeine metabolism and its clearance. Caffeine, on the other hand, antagonizes adenosine A(2A) receptor and regulates dopamine signaling through dopamine transporter (DAT). The present study was undertaken to investigate the expression of CYP1A2, adenosine A(2A) receptor and DAT in mouse striatum and to assess their levels in 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropryridine (MPTP) treated mouse striatum with and without caffeine treatment. The animals were treated intraperitoneally daily with caffeine (20 mg/kg) for 8 weeks, followed by MPTP (20 mg/kg)+ caffeine (20 mg/kg) for 4 weeks or vice versa, along with respective controls. Tyrosine hydroxylase immunoreactivity, levels of dopamine and 1-methyl 4-phenylpyridinium ion (MPP(+)), expressions of CYP1A2, adenosine A(2A) receptor and DAT and CYP1A2 catalytic activity were measured in control and treated mouse brain. Caffeine partially protected MPTP-induced neurodegenerative changes and modulated MPTP-mediated alterations in the expression and catalytic activity of CYP1A2, expression of adenosine A(2A) receptor and DAT. The results demonstrate that caffeine alters the striatal CYP1A2, adenosine A(2A) receptor and DAT expressions in mice exposed to MPTP.