Instruct: Given a question, retrieve documents that answer the question.
Query: What About the Caffeine?
OBJECTIVE: The beneficial effects of human caffeine consumption deserve clarification. METHODS: A detailed literature review was conducted and summarized. RESULTS: A large body of scientific evidence describes the beneficial effects of human caffeine consumption on a number of physiologic systems. CONCLUSION: The consumption of moderate amounts of caffeine 1) increases energy availability, 2) increases daily energy expenditure, 3) decreases fatigue, 4) decreases the sense of effort associated with physical activity, 5) enhances physical performance, 6) enhances motor performance, 7) enhances cognitive performance, 8) increases alertness, wakefulness, and feelings of "energy," 9) decreases mental fatigue, 10) quickens reactions, 11) increases the accuracy of reactions, 12) increases the ability to concentrate and focus attention, 13) enhances short-term memory, 14) increases the ability to solve problems requiring reasoning, 15) increases the ability to make correct decisions, 16) enhances cognitive functioning capabilities and neuromuscular coordination, and 17) in otherwise healthy non-pregnant adults is safe. Copyright © 2010 Elsevier Inc. All rights reserved.
1. The effects of grapefruit juice and naringenin on the activity of the human cytochrome P450 isoform CYP1A2 were evaluated using caffeine as a probe substrate. 2. In vitro naringin was a potent competitive inhibitor of caffeine 3-demethylation by human liver microsomes (Ki = 7-29 microM). 3. In vivo grapefruit juice (1.2 l day-1 containing 0.5 g l-1 naringin, the glycone form of naringenin) decreased the oral clearance of caffeine by 23% (95% CI: 7%-30%) and prolonged its half-life by 31% (95% CI: 20%-44%) (n = 12). 4. We conclude that grapefruit juice and naringenin inhibit CYP1A2 activity in man. However, the small effect on caffeine clearance in vivo suggests that in general the ingestion of grapefruit juice should not cause clinically significant inhibition of the metabolism of other drugs that are substrates of CYPIA2.
BACKGROUND: Coffee and tea are believed to cause gastro-oesophageal reflux; however, the effects of these beverages and of their major component, caffeine, have not been quantified. The aim of this study was to evaluate gastro-oesophageal reflux induced by coffee and tea before and after a decaffeination process, and to compare it with water and water-containing caffeine. METHODS: Three-hour ambulatory pH-metry was performed on 16 healthy volunteers, who received 300 ml of (i) regular coffee, decaffeinated coffee or tap water (n = 16), (ii) normal tea, decaffeinated tea, tap water, or coffee adapted to normal tea in caffeine concentration (n = 6), and (iii) caffeine-free and caffeine-containing water (n = 8) together with a standardized breakfast. RESULTS: Regular coffee induced a significant (P < 0.05) gastro-oesophageal reflux compared with tap water and normal tea, which were not different from each other. Decaffeination of coffee significantly (P < 0.05) diminished gastro-oesophageal reflux, whereas decaffeination of tea or addition of caffeine to water had no effect. Coffee adapted to normal tea in caffeine concentration significantly (P < 0.05) increased gastro-oesophageal reflux. CONCLUSIONS: Coffee, in contrast to tea, increases gastro-oesophageal reflux, an effect that is less pronounced after decaffeination. Caffeine does not seem to be responsible for gastro-oesophageal reflux which must be attributed to other components of coffee.
Caffeine is the most widely used pharmacologic substance in the world. It is found in common nonessential grocery items (e.g., coffee, tea, cocoa, and chocolate). The effects of caffeine on cardiovascular diseases, including hypertension, remain controversial, and there is little information on its direct effect on vascular function. The purpose of this study was to determine the effect of caffeine on endothelial function in humans. This study was a double-blind, randomized placebo and active drug study. Forearm blood flow (FBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and to sodium nitroprusside, an endothelium-independent vasodilator, were evaluated in healthy young men before and after the oral administration of caffeine 300 mg (n = 10) or placebo (n = 10). FBF was measured by using a strain-gauge plethysmograph. Caffeine significantly increased systolic and diastolic blood pressures by 6.0 +/- 6.0 and 2.6 +/- 3.1 mm Hg (p <0.05), respectively, but did not alter heart rate or baseline FBF. Caffeine augmented the FBF responses to ACh from 21.2 +/- 7.1 to 26.6 +/- 8.1 ml/min/100 ml tissue (p <0.05), whereas sodium nitroprusside-stimulated vasodilation was not altered by caffeine administration. The intra-arterial infusion of N(G)-monomethyl-L-arginine, a nitric oxide synthase inhibitor, abolished the caffeine-induced augmentation of FBF response to ACh. In the placebo group, the ACh- and sodium nitroprusside-stimulated vasodilation was similar before and after the follow-up period. In conclusion, these findings suggest that the acute administration of caffeine augments endothelium-dependent vasodilation in healthy young men through an increase in nitric oxide production.
Coffee is the leading worldwide beverage after water and its trade exceeds US $10 billion worldwide. Controversies regarding its benefits and risks still exist as reliable evidence is becoming available supporting its health promoting potential; however, some researchers have argued about the association of coffee consumption with cardiovascular complications and cancer insurgence. The health-promoting properties of coffee are often attributed to its rich phytochemistry, including caffeine, chlorogenic acid, caffeic acid, hydroxyhydroquinone (HHQ), etc. Many research investigations, epidemiological studies, and meta-analyses regarding coffee consumption revealed its inverse correlation with that of diabetes mellitus, various cancer lines, Parkinsonism, and Alzheimer's disease. Moreover, it ameliorates oxidative stress because of its ability to induce mRNA and protein expression, and mediates Nrf2-ARE pathway stimulation. Furthermore, caffeine and its metabolites help in proper cognitive functionality. Coffee lipid fraction containing cafestol and kahweol act as a safeguard against some malignant cells by modulating the detoxifying enzymes. On the other hand, their higher levels raise serum cholesterol, posing a possible threat to coronary health, for example, myocardial and cerebral infarction, insomnia, and cardiovascular complications. Caffeine also affects adenosine receptors and its withdrawal is accompanied with muscle fatigue and allied problems in those addicted to coffee. An array of evidence showed that pregnant women or those with postmenopausal problems should avoid excessive consumption of coffee because of its interference with oral contraceptives or postmenopausal hormones. This review article is an attempt to disseminate general information, health claims, and obviously the risk factors associated with coffee consumption to scientists, allied stakeholders, and certainly readers. © Taylor and Francis Group, LLC
The effect of beverages prepared from the dried calyx of the flowers of Hibiscus sabdariffa on the excretion of diclofenac was investigated using a controlled study in healthy human volunteers. A high pressure liquid chromatographic method was used to analyse the 8 h urine samples collected after the administration of diclofenac with 300 mL (equivalent to 8.18 mg anthocyanins) of the beverage administered daily for 3 days. An unpaired two-tailed t-test was used to analyse for significant difference observed in the amount of diclofenac excreted before and after administration of the beverage. There was a reduction in the amount of diclofenac excreted and the wide variability observed in the control with the water beverage of Hibiscus sabdariffa (p < 0.05). There is an increasing need to counsel patients against the use of plant beverages with drugs.
Background Many studies have examined whether caffeine, alcohol, or specific beverages containing these affect fertility in women. However most of these studies have retrospectively collected information on alcohol and caffeine intake, making the results susceptible to biases. Methods We followed 18,555 married women without a history of infertility for 8 years as they attempted to become (or became) pregnant. Diet was measured twice during this period and prospectively related to the incidence of ovulatory disorder infertility. Results There were 438 incident report of ovulatory disorder infertility during follow-up. Intakes of alcohol and caffeine were unrelated to the risk of ovulatory disorder infertility. The multivariate-adjusted relative risk (RR), 95% confidence interval (CI), P for trend comparing the highest to lowest categories of intake were 1.11 (0.76–1.64; 0.78) for alcohol and 0.86 (0.61–1.20; 0.44) for total caffeine. However, intake of caffeinated soft drinks was positively related to ovulatory disorder infertility. The multivariate-adjusted RR 95% CI, and P for trend comparing the highest to lowest categories of caffeinated soft drink consumption were 1.47 (1.09–1.98; 0.01). Similar associations were observed for noncaffeinated, sugared, diet and total soft drinks. Conclusions Our findings do not support the hypothesis that alcohol and caffeine impair ovulation to the point of decreasing fertility. The association between soft drinks and ovulatory disorder infertility appears not to be attributable to their caffeine or sugar content, and deserves further investigation.
The use of substances as the substrate for atrial fibrillation is not frequently recognized. Chocolate is derived from the roasted seeds of the plant theobroma cacao and its components are the methylxanthine alkaloids theobromine and caffeine. Caffeine is a methylxanthine whose primary biological effect is the competitive antagonism of the adenosine receptor. Normal consumption of caffeine was not associated with risk of atrial fibrillation or flutter. Sympathomimetic effects, due to circulating catecholamines cause the cardiac manifestations of caffeine overdose toxicity, produce tachyarrhythmias such as supraventricular tachycardia, atrial fibrillation, ventricular tachycardia, and ventricular fibrillation.The commonly used doses of inhaled or nebulized salbutamol induced no acute myocardial ischaemia, arrhythmias or changes in heart rate variability in patients with coronary artery disease and clinically stable asthma or chronic obstructive pulmonary disease. Two-week salbutamol treatment shifts the cardiovascular autonomic regulation to a new level characterized by greater sympathetic responsiveness and slight beta2-receptor tolerance. We present a case of atrial fibrillation associated with chocolate intake abuse in a 19-year-old Italian woman with chronic salbutamol inhalation abuse. This case focuses attention on chocolate intake abuse associated with chronic salbutamol abuse as the substrate for atrial fibrillation. Copyright © 2008 Elsevier Ireland Ltd. All rights reserved.
Although coffee is largely consumed by adults in Western countries, controversy exists about its impact on the cardiovascular system. We recently demonstrated that caffeinated and decaffeinated espresso coffee have different acute effects on endothelial function in healthy subjects, measured using flow-mediated dilation (FMD) of the brachial artery. In this study, we measured the anti-oxidant capacity of two coffee substances in terms of free stable radical 2,2-diphenyl-1-picryl-hydrazyl 50% inhibition (I(50) DPPH). The caffeinated coffee had a slightly higher anti-oxidant capacity than decaffeinated espresso coffee (I(50) DPPH: 1.13±0.02 vs 1.30±0.03 μl; P<0.001). We suggest that the unfavourable effects observed after caffeinated coffee ingestion are due to caffeine and that the antioxidant activity is responsible for the increased FMD observed after decaffeinated coffee ingestion. Further clinical and epidemiological studies are needed to understand the chronic effects of coffee consumption on health.
Background Caffeine is the world’s most widely used central nervous system stimulant, with about 80% consumed in form of coffee. However, studies that analyzed prospectively the relation of coffee or caffeine consumption and depression risk are scarce. Methods A total of 50,739 U.S. women (mean age=63 years) free from depressive symptoms at baseline (1996) were prospectively followed until 2006. Caffeine and coffee consumption, and other caffeinated and decaffeinated beverages, were obtained from validated questionnaires completed between 1980 through 2002 and computed as cumulative average of consumption with a 2-year latency applied. Clinical depression was defined as reporting both physician-diagnosed depression and antidepressant use. Relative risks of clinical depression were estimate using Cox proportional hazards regression models. Results During 10 years of follow-up (1996–2006), 2,607 incident cases of depression were identified. Compared to women consuming caffeinated coffee less frequently (≤1 cup/wk), multivariate relative risk of depression was 0.85 (95% confidence interval [CI], 0.75 to 0.95) for those consuming 2–3 cups/d and 0.80 (95%CI, 0.64 to 0.99; P trend <0.001) for those consuming ≥4 cups/d. Multivariate relative risk for depression was 0.80 (95%CI, 0.68 to 0.95; P trend=0.02) for women in the highest (≥550 mg/d) vs. lowest (<100 mg/d) of the 5 caffeine consumption categories. Decaffeinated coffee was not associated with depression risk. Conclusions In this large longitudinal study we found that depression risk decreases with increasing caffeinated coffee consumption. Further investigations are needed to confirm this finding and to determine whether usual caffeinated coffee consumption may contribute to depression prevention.
The inhibitory effect of Old Coke, caffeine-free New Coke, New Coke, Diet Coke and Pepsi-Cola on human sperm motility was studied with a trans-membrane migration method. None of them could decrease sperm motility to less than 70% of control within one hour. A previous study which claimed a marked variation of spermicidal potencies among different formulations of Coca-Cola could not be confirmed. Even if cola has a spermicidal effect, its potency is relatively weak as compared with other well-known spermicidal agents.
The U.S. Food and Drug Administration (FDA) should reevaluate its position on aspartame as being safe under all conditions. Animal bioassay results predict human cancer risks, and a recent animal study confirms that there is a potential aspartame risk to humans. Aspartame is produced and packaged in China for domestic use and global distribution. Japan, France, and the United States are also major producers. No study of long-term adverse occupational health effects on aspartame workers have been conducted. The FDA should consider sponsoring a prospective epidemiologic study of aspartame workers.
PURPOSE: Epidemiological studies in women have revealed an association between caffeine intake and urinary incontinence, although evidence among men is limited. Therefore, we evaluated the association between caffeine intake and urinary incontinence in United States men. MATERIALS AND METHODS: Data were used from male NHANES (National Health and Nutrition Examination Surveys) 2005-2006 and 2007-2008 participants. Urinary incontinence was defined using a standard questionnaire with Incontinence Severity Index scores 3 or greater categorized as moderate to severe. Structured dietary recall was used to determine caffeine consumption (mg per day), water intake (gm per day) and total dietary moisture (gm per day). Stepwise multivariable logistic regression models were used to assess the association between caffeine intake at or above the 75th and 90th percentiles and moderate to severe urinary incontinence, controlling for potential confounders, urinary incontinence risk factors and prostate conditions in men age 40 years or older. RESULTS: Of the 5,297 men 3,960 (75%) were 20 years old or older with complete data. Among these men the prevalence of any urinary incontinence was 12.9% and moderate to severe urinary incontinence was 4.4%. Mean caffeine intake was 169 mg per day. Caffeine intake at the upper 75th percentile (234 mg or more daily) and 90th percentile (392 mg or more per day) was significantly associated with having moderate to severe urinary incontinence (1.72, 95% 1.18-2.49 and 2.08, 95% 1.15-3.77, respectively). In addition, after adjusting for prostate conditions, the effect size for the association between caffeine intake and moderate to severe urinary incontinence remained. CONCLUSIONS: Caffeine consumption equivalent to approximately 2 cups of coffee daily (250 mg) is significantly associated with moderate to severe urinary incontinence in United States men. Our findings support the further study of caffeine modification in men with urinary incontinence. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
Objective To evaluate the association between coffee and caffeine consumption and suicide risk in three large-scale cohorts of U.S. men and women. Methods We accessed data of 43,599 men enrolled in the Health Professionals Follow-up Study (HPFS, 1988–2008), 73,820 women in the Nurses’ Health Study (NHS, 1992–2008), and 91,005 women in the NHS II (1993–2007). Consumption of caffeine, coffee, and decaffeinated coffee, was assessed every four years by validated food-frequency questionnaires. Deaths from suicide were determined by physician review of death certificates. Multivariate adjusted relative risks (RRs) were estimated with Cox proportional hazard models. Cohort specific RRs were pooled using random-effect models. Results We documented 277 deaths from suicide. Compared to those consuming ≤1 cup/week of caffeinated coffee (≤8 oz/237 ml), the pooled multivariate RR (95% confidence interval [CI]) of suicide was 0.55 (0.38–0.78) for those consuming 2–3 cups/day and 0.47 (0.27–0.81) for those consuming ≥4 cups/day (P trend <0.001). The pooled multivariate RR (95% CI) for suicide was 0.75 (0.63–0.90) for each increment of 2 cups/day of caffeinated coffee and 0.77 (0.63–0.93) for each increment of 300 mg/day of caffeine. Conclusions These results from three large cohorts support an association between caffeine consumption and lower risk of suicide.
Studies that have addressed the association between the intake of coffee or caffeine and Parkinson's disease (PD) were conducted mainly in Western countries. Little is known about this relationship in an Asian population. Therefore, we performed an assessment of the association of the intake of coffee, other caffeine-containing beverages, and caffeine with the risk of PD in Japan. The study involved 249 PD cases and 368 control subjects. Information on dietary factors was obtained through a self-administered diet history questionnaire. Adjustment was made for sex, age, region of residence, educational level, pack-years of smoking, body mass index, the dietary glycemic index, and intake of cholesterol, vitamin E, β-carotene, vitamin B(6,) alcohol, and iron. Intake of coffee, black tea, and Japanese and Chinese teas was significantly inversely associated with the risk of PD: the adjusted odds ratios in comparison of the highest with the lowest quartile were 0.52, 0.58, and 0.59, respectively (95% confidence intervals = 0.30-0.90, 0.35-0.97, and 0.35-0.995, respectively). A clear inverse dose-response relationship between total caffeine intake and PD risk was observed. We confirmed that the intake of coffee and caffeine reduced the risk of PD. Furthermore, this is the first study to show a significant inverse relationship between the intake of Japanese and Chinese teas and the risk of PD. Copyright © 2011 Elsevier Ltd. All rights reserved.
Objective: Epidemiologic studies consistently link caffeine, a nonselective adenosine antagonist, to lower risk of Parkinson disease (PD). However, the symptomatic effects of caffeine in PD have not been adequately evaluated. Methods: We conducted a 6-week randomized controlled trial of caffeine in PD to assess effects upon daytime somnolence, motor severity, and other nonmotor features. Patients with PD with daytime somnolence (Epworth >10) were given caffeine 100 mg twice daily ×3 weeks, then 200 mg twice daily ×3 weeks, or matching placebo. The primary outcome was the Epworth Sleepiness Scale score. Secondary outcomes included motor severity, sleep markers, fatigue, depression, and quality of life. Effects of caffeine were analyzed with Bayesian hierarchical models, adjusting for study site, baseline scores, age, and sex. Results: Of 61 patients, 31 were randomized to placebo and 30 to caffeine. On the primary intention-to-treat analysis, caffeine resulted in a nonsignificant reduction in Epworth Sleepiness Scale score (−1.71 points; 95% confidence interval [CI] −3.57, 0.13). However, somnolence improved on the Clinical Global Impression of Change (+0.64; 0.16, 1.13, intention-to-treat), with significant reduction in Epworth Sleepiness Scale score on per-protocol analysis (−1.97; −3.87, −0.05). Caffeine reduced the total Unified Parkinson's Disease Rating Scale score (−4.69 points; −7.7, −1.6) and the objective motor component (−3.15 points; −5.50, −0.83). Other than modest improvement in global health measures, there were no changes in quality of life, depression, or sleep quality. Adverse events were comparable in caffeine and placebo groups. Conclusions: Caffeine provided only equivocal borderline improvement in excessive somnolence in PD, but improved objective motor measures. These potential motor benefits suggest that a larger long-term trial of caffeine is warranted. Classification of evidence: This study provides Class I evidence that caffeine, up to 200 mg BID for 6 weeks, had no significant benefit on excessive daytime sleepiness in patients with PD.
Background Caffeine is one of the most widely consumed pharmacologically active substances. Its acute effect on myocardial blood flow is widely unknown. Our aim was to assess the acute effect of caffeine in a dose corresponding to two cups of coffee on myocardial blood flow (MBF) in coronary artery disease (CAD). Methodology/Principal Findings MBF was measured with 15O-labelled H2O and Positron Emission Tomography (PET) at rest and after supine bicycle exercise in controls (n = 15, mean age 58±13 years) and in CAD patients (n = 15, mean age 61±9 years). In the latter, regional MBF was assessed in segments subtended by stenotic and remote coronary arteries. All measurements were repeated fifty minutes after oral caffeine ingestion (200 mg). Myocardial perfusion reserve (MPR) was calculated as ratio of MBF during bicycle stress divided by MBF at rest. Resting MBF was not affected by caffeine in both groups. Exercise-induced MBF response decreased significantly after caffeine in controls (2.26±0.56 vs. 2.02±0.56, P<0.005), remote (2.40±0.70 vs. 1.78±0.46, P<0.001) and in stenotic segments (1.90±0.41 vs. 1.38±0.30, P<0.001). Caffeine decreased MPR significantly by 14% in controls (P<0.05 vs. baseline). In CAD patients MPR decreased by 18% (P<0.05 vs. baseline) in remote and by 25% in stenotic segments (P<0.01 vs. baseline). Conclusions We conclude that caffeine impairs exercise-induced hyperaemic MBF response in patients with CAD to a greater degree than age-matched controls.
Despite its antioxidant capacity and well-known health benefits, yerba mate tea (Ilex paraguariensis) has been shown to possess some genotoxic and mutagenic activities and to increase incidence of some types of cancer. The aim of this study was to estimate the cyto- and genotoxicity of mate tea in human peripheral lymphocytes in vitro. We found that yerba mate extract induced a concentration-dependent, statistically significant increase in the level of apoptotic and necrotic cells and a decrease in the nuclear division index (NDI). Mate-exposed lymphocytes had a reduced transcriptional rDNA activity, which may be due to the stress conditions, and showed an elevated production of micronuclei. The FISH technique revealed the appearance of an acrocentric signal in mate-induced micronuclei, which suggests that under these conditions yerba mate extract may display aneugenic activity. Since caffeine is one of the most abundant compounds found in the dry mass of mate, we conducted additional experiments with caffeine alone. We showed that caffeine used at the same concentrations manifests a more potent cyto- and genotoxic effect that may account, at least in part, for the disadvantageous effects observed for yerba mate extract.
Coffee drinking has been associated with increased serum cholesterol levels in some, but not all, studies. A Medline search of the English-language literature published prior to December 1998, a bibliography review, and consultations with experts were performed to identify 14 published trials of coffee consumption. Information was abstracted independently by two reviewers using a standardized protocol. With a random-effects model, treatment effects were estimated by pooling results from individual trials after weighting the results by the inverse of total variance. A dose-response relation between coffee consumption and both total cholesterol and LDL cholesterol was identified (p < 0.01). Increases in serum lipids were greater in studies of patients with hyperlipidemia and in trials of caffeinated or boiled coffee. Trials using filtered coffee demonstrated very little increase in serum cholesterol. Consumption of unfiltered, but not filtered, coffee increases serum levels of total and LDL cholesterol.
12 healthy volunteers on a controlled aluminium (Al) diet each consumed a tea infusion (500 ml/70 kg body weight), with either milk or lemon juice as additives, or mineral water, following a three-way crossover design. The concentrations of Al were determined in the diet, mineral water and tea infusions, and in plasma samples collected before and up to 24 hr after consumption of tea or water, using graphite-furnace atomic absorption spectrophotometry or inductively coupled plasma emission spectrometry. Consumption of up to 1.60 mg Al from tea with milk or lemon juice did not increase plasma Al levels compared with consumption of approximately 0.001 mg Al from mineral water. The results suggest that, in the short-term, drinking tea does not contribute significantly to the total body burden of Al.
The effects of different polyphenol-containing beverages on Fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-Fe. The test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (Matricaria recutita L.), vervain (Verbena officinalis L.), lime flower (Tilia cordata Mill.), pennyroyal (Mentha pulegium L.) and peppermint (Mentha piperita L.), or complex polyphenol polymerization products (black tea and cocoa). All beverages were potent inhibitors of Fe absorption and reduced absorption in a dose-dependent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20-50 mg total polyphenols/serving reduced Fe absorption from the bread meal by 50-70%, whereas beverages containing 100-400 mg total polyphenols/serving reduced Fe absorption by 60-90%. Inhibition by black tea was 79-94%, peppermint tea 84%, pennyroyal 73%, cocoa 71%, vervain 59%, lime flower 52% and camomile 47%. At an identical concentration of total polyphenols, black tea was more inhibitory than cocoa, and more inhibitory than herb teas camomile, vervain, lime flower and pennyroyal, but was of equal inhibition to peppermint tea. Adding milk to coffee and tea had little or no influence on their inhibitory nature. Our findings demonstrate that herb teas, as well as black tea, coffee and coca can be potent inhibitors of Fe absorption. This property should be considered when giving dietary advice in relation to Fe nutrition.
Coffee, after water, is the most widely consumed beverage in the United States, and is the principal source of caffeine intake among adults. The biological effects of coffee may be substantial and are not limited to the actions of caffeine. Coffee is a complex beverage containing hundreds of biologically active compounds, and the health effects of chronic coffee intake are wide ranging. From a cardiovascular (CV) standpoint, coffee consumption may reduce the risk of type 2 diabetes mellitus and hypertension, as well as other conditions associated with CV risk such as obesity and depression; but it may adversely affect lipid profiles depending on how the beverage is prepared. Regardless, a growing body of data suggests that habitual coffee consumption is neutral to beneficial regarding the risks of a variety of adverse CV outcomes including coronary heart disease, congestive heart failure, arrhythmias, and stroke. Moreover, large epidemiological studies suggest that regular coffee drinkers have reduced risks of mortality, both CV and all-cause. The potential benefits also include protection against neurodegenerative diseases, improved asthma control, and lower risk of select gastrointestinal diseases. A daily intake of ∼2 to 3 cups of coffee appears to be safe and is associated with neutral to beneficial effects for most of the studied health outcomes. However, most of the data on coffee's health effects are based on observational data, with very few randomized, controlled studies, and association does not prove causation. Additionally, the possible advantages of regular coffee consumption have to be weighed against potential risks (which are mostly related to its high caffeine content) including anxiety, insomnia, tremulousness, and palpitations, as well as bone loss and possibly increased risk of fractures. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Except for conflicting evidence about coffee and risk of coronary disease, coffee and tea are not linked to major causes of death. Because of widespread use of both beverages and limitations of prior studies, concern persists. Using Cox models (ten covariates) we studied relations in 128,934 persons to 4501 subsequent deaths. Except for slightly increased risk from acute myocardial infarction among heavier (> or = 4 cups/d) coffee users (relative risk versus nondrinkers = 1.4, 95% confidence interval = 1.0 to 1.9, P = 0.07), there was no increased risk of mortality for all deaths (relative risk per cup of coffee per day = 0.99, 95% confidence interval = 0.97 to 1.01; relative risk per cup of tea per day = 0.98, 95% confidence interval = 0.96 to 1.00) or major causes in adjusted analyses. Coffee was related to lower risk of liver cirrhosis death (relative risk per cup of coffee per day = 0.77, 95% confidence interval = 0.67 to 0.89). Use of both beverages was related to a lower risk of suicide, progressively lower at higher coffee intake (relative risk per cup of coffee per day = 0.87, 95% confidence interval = 0.77 to 0.98). We conclude that coffee and tea have no overall relation to mortality risk. If coffee increases coronary risk, this is balanced by an unexplained lower risk of other conditions, notably cirrhosis and suicide.
BACKGROUND/OBJECTIVES: Coffee is the most widely consumed beverage in the world, but its effect on the cardiovascular system has not been fully understood. Coffee contains caffeine and antioxidants, which may influence endothelial function, both of which have not yet been investigated. The objective of this study was to investigate the acute effects of coffee on endothelial function measured by brachial artery flow-mediated dilation (FMD). SUBJECTS/METHODS: A total of 20 (10 males and 10 females) healthy non-obese subjects underwent a double-blind, crossover study. Subjects ingested one cup of caffeinated (CC) and one cup of decaffeinated (DC) Italian espresso coffee in random order at 5- to 7-day intervals. RESULTS: Following CC ingestion, FMD decreased progressively and significantly (mean+/-s.e.m.: 0 min, 7.7+/-0.6; 30 min, 6.3+/-0.7; 60 min, 6.0+/-0.8%; ANOVA (analysis of variance), P<0.05), but it did not significantly increase after DC ingestion (0 min, 6.9+/-0.6; 30 min, 8.1+/-0.9; 60 min, 8.5+/-0.9%; P=0.115). Similarly, CC significantly increased both systolic and diastolic blood pressure; this effect was not observed after DC ingestion. Blood glucose concentrations remained unchanged after ingestion of both CC and DC, but insulin (0 min, 15.8+/-0.9; 60 min, 15.0+/-0.8 muU/ml; P<0.05) and C-peptide (0 min, 1.25+/-0.09; 60 min, 1.18+/-0.09 ng/ml; P<0.01) blood concentrations decreased significantly only after CC ingestion. CONCLUSIONS: CC acutely induced unfavorable cardiovascular effects, especially on endothelial function. In the fasting state, insulin secretion is also likely reduced after CC ingestion. Future studies will determine whether CC has detrimental clinically relevant effects, especially in unhealthy subjects.
The present paper explores the level of evidence required to justify giving dietary advice to the public. There are important practical differences between the development of public health nutrition guidelines and guidelines for clinical practice. While the gold standard for evidence for clinical practice guidelines is a meta-analysis of a number of randomised controlled trials, this is often unrealistic and sometimes unethical for the evaluation of public health nutrition interventions. Hence, epidemiological studies make up the bulk of evidence for nutrition guidelines. Tea and coffee are an interesting case study in relation to this issue. They are two of the most commonly consumed beverages worldwide, yet there is little dietary advice on their use. The evidence for a relationship between coffee or tea consumption and several diseases is discussed. The available studies, predominantly epidemiological, together with animal and in vitro studies, indicate that coffee and tea are both safe beverages. However, tea is the healthier option because it has a possible role in the prevention of several cancers and CVD. While the evidence for such relationships is not strong, the public will continue to drink both tea and coffee, and will continue to ask nutritionists to make recommendations. It is therefore argued that advice should be given on the best available data, as waiting for complete data to become available could have severe consequences for public health.