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Coffee drinking increases levels of urinary hydrogen peroxide detected in healthy human volunteers.

Freshly-voided human urine contains significant concentrations of hydrogen peroxide (H2O2). This H2O2 appears to arise in whole or in part by superoxide-dependent autoxidation of urinary biomolecules. Since instant coffee also contains high levels of H2O2, we examined the effect of coffee drinking on urinary levels of H2O2. Studies on healthy human volunteers showed that coffee drinking is rapidly and reproducibly followed by increased levels of H2O2 detectable in the urine for up to 2 h after drinking the coffee. The levels of H2O2 detected in urine suggest that exposure of human tissues to H2O2 may be greater than is commonly supposed. It is possible that H2O2 in urine could act as an antibacterial agent, and that H2O2 is involved in the regulation of glomerular function.

Adult↗

Coffee drinking: a minor risk factor for bone loss and fractures.

The influence of coffee drinking as a possible risk factor for loss of bone mass was assessed in a cohort of 619 70-year-old men and women who were examined with dual photon absorptiometry of the right calcaneum. A high consumption of coffee was significantly associated with a lower bone mass, deteriorated dental state, lower socio-economic level and a higher consumption of tobacco. In non-smoking women a bivariate relationship was found between the daily consumption of three or more cups of coffee and a low bone mass (p less than 0.01). However, in a stepwise logistic regression model, only tobacco smoking, body mass index, body height, physical activity and a deteriorated dental state were found to be significant predictive factors for a low bone mineral content. Bone mass and tobacco smoking were the only significant predictive factors for fractures before the ages of 70 and 76 years. Coffee drinking was not a contributory independent risk factor for loss of bone mass and fractures in this population study.

Aged↗

The relationship between coffee consumption and lipid levels in young and older people in the Heidelberg-Michelstadt-Berlin study.

The relationship between coffee consumption and serum lipid levels was studied in a randomly selected sample of 395 young and 385 elderly adults in the Federal Republic of Germany. Analyses were done separately for men and women and for young and older people. After adjustment for body mass index, activity level, smoking, total energy intake, dietary fat, fish, milk, tea and alcohol consumption and oral contraceptive use a statistically significant increase in total serum- and LDL-cholesterol levels with increased coffee consumption was observed in the group of young men only. In this subgroup a difference of 0.11 mmol.l-1 serum cholesterol and of 0.10 mmol.l-1 LDL cholesterol for each additional cup of coffee consumed daily was calculated. This is one of the few studies that includes elderly people. No significant trend was seen between coffee consumption and serum- or LDL-cholesterol levels in the elderly.

Adult↗

Coffee and cardiovascular risk: epidemiological findings in Austria.

The results of studies on the connection between the consumption of coffee and cardiovascular risk factors have been conflicting, particularly concerning serum lipids. We examined several associations in a representative sample of 1203 men and women between 25 and 64 years of age in the state of Vorarlberg, Austria. Coffee consumption correlated significantly (p less than 0.001) with the number of cigarettes smoked per day (men: r = 0.30; women: r = 0.26) and the prevalence of smokers (men: r = 0.27; women: r = 0.25). We found no adverse effect of coffee on blood lipids or lipoproteins. The lack of evidence was independent of smoking habits in both sexes. We suggest that the lack of evidence is due to the usual method of preparing coffee in Vorarlberg, ie percolated or as 'Espresso'.

Adult↗

Are coffee and tea consumption associated with urinary tract cancer risk? A systematic review and meta-analysis.

BACKGROUND: Narrative reviews have concluded that there is a small association between coffee consumption and an increased risk of urinary tract cancer, possibly due to confounding by smoking. No association for tea consumption has been indicated. This systematic review attempts to summarize and quantify these associations both unadjusted and adjusted for age, smoking and sex. METHOD: Thirty-four case-control and three follow-up studies were included in this systematic review. Summary odds ratios (OR) were calculated by meta-regression analyses. RESULTS: The unadjusted summary OR indicated a small increased risk of urinary tract cancer for current coffee consumers versus non-drinkers. The adjusted summary OR were: 1.26 (95% CI : 1.09-1.46) for studies with only men, 1.08 (95% CI : 0.79-1.46) for studies with only women and 1.18 (95% CI : 1.01-1.38) for studies with men and women combined. Neither unadjusted nor adjusted summary OR provided evidence for a positive association between tea consumption and urinary tract cancer. Even though studies differed in methodology, the results were rather consistent. We did not perform dose-response analyses for coffee and tea consumption due to sparse data. CONCLUSIONS: In accordance with earlier reviews, we found that coffee consumption increases the risk of urinary tract cancer by approximately 20%. The consumption of tea seems not to be related to an increased risk of urinary tract cancer.

Age Factors↗

The J-shaped effect of coffee consumption on the risk of developing acute coronary syndromes: the CARDIO2000 case-control study.

The effect of coffee consumption on cardiovascular disease has been debated for many years. In this work, we evaluated the association between coffee consumption and the risk of developing acute coronary syndromes, based on a random sample of 848 patients with their first coronary heart disease event and 1078 frequency-matched controls with no cardiovascular disease in their medical history, from the entire country. The multivariate analysis raises a J-shaped association between the risk of developing acute coronary syndromes and the quantity of coffee consumed per day. In particular, the odds ratios for moderate (<300 mL/d), heavy (300-600 mL/d), and very heavy (>600 mL/d), consumption, relative to no consumption, were 0.69 (95% CI, 0.50-0.86), 1.56 (95% CI, 1.10-2.34) and 3.10 (95% CI, 1.82-5.26), respectively, after controlling for the presence of hypertension, hypercholesterolemia, diabetes mellitus, family history of premature coronary heart disease, physical activity status, smoking habits, BMI, alcohol consumption, triglycerides, consumption of several food items, depression scale score and education status. The suggested J-shaped association between coffee consumption and the risk of developing acute coronary syndromes may partially explain the conflicting results from other studies in the past.

Aged↗

Quinides of roasted coffee enhance insulin action in conscious rats.

Consumption of large amounts of coffee has been shown to decrease the incidence of type 2 diabetes. However, the specific compounds and mechanisms responsible for this effect are not known. The aim of this study was to determine the effects of a decaffeinated coffee extract and a synthetic quinide, representative of those found in roasted coffee, 3,4-diferuloyl-1,5-quinolactone, on insulin-stimulated glucose disposal and muscle glucose uptake. Experiments were performed on conscious rats during hyperinsulinemic, euglycemic clamps receiving gastric infusions of saline, a decaffeinated coffee extract (DECAF) (220 mg/kg), or 3,4-diferuloyl-1,5-quinide (DIFEQ) (110 mg/kg). Following treatment, rats received an intravenous bolus of deoxy-[2-3H] glucose to assess muscle glucose uptake (Rg, micromol x 100 g(-1) x min(-1)). Glucose infusions [mg/(kg x min)] required to maintain euglycemia during the tracer period were higher with DIFEQ (14.6 +/- 0.7) than with saline (10.8 +/- 0.7) and DECAF (11.5 +/- 1.1). Despite increased glucose requirements, Rg in skeletal (soleus, gastrocnemius, superficial vastus lateralis) and cardiac muscle were unchanged. DECAF or DIFEQ did not affect heart rate, blood pressure, plasma nonesterified fatty acids or liver aminotransferase activity. These results demonstrate that DIFEQ increases whole-body glucose disposal independently of skeletal muscle Rg.

Animals↗

Hydrogen peroxide and coffee induce G:C-->T:A transversions in the lacI gene of catalase-defective Escherichia coli.

The mutagenicity of hydrogen peroxide (H2O2) was compared with that of coffee, a complex mixture which generates H2O2. An Escherichia coli strain defective in catalase activity (katG katE double mutant) and carrying a single copy mucAB (pRW144) plasmid was constructed to enhance the mutagenic response to oxidants. The ability of the mucAB genes to influence the type, frequency and distribution of H2O2-induced mutations was also investigated in isogenic bacteria lacking pRW144. Induced mutational spectra were characterized and compared with that of spontaneous mutagenesis. A total of 444 independent forward mutations affecting the first 210 bp of the lacI gene were identified by DNA sequence analysis. The spontaneous mutation spectrum showed no bias (P = 0.52) for substitutions at G:C base pairs. In contrast, in the H2O2-induced spectrum substitutions occurred preferentially at G:C base pairs (P < 0.0001) with a preponderance of G:C-->T:A transversions (43.4% of H2O2-induced mutants versus 17.3% of spontaneous mutants). These data support the view that 7,8-dihydro-8-oxoguanine is the main premutagenic lesion induced by H2O2 and that catalase-defective bacteria have elevated levels of 8-oxoguanine in chromosome DNA after H2O2 exposure. Coffee produced a similar distribution of mutational events as H2O2 (P > 0.05), suggesting that this compound may be the main cause of the coffee-induced mutagenesis. The presence of plasmid pRW144 did not affect the frequency of H2O2-induced G:C-->T:A transversions, but caused an increase in A:T-->T:A transversions and a decrease in -1 base frameshifts. Although the frequencies of G:C-->T:A transversions were similar in all three induced spectra (H2O2 and coffee +/- pRW144), differences were observed in location of mutations throughout the target gene.

Acatalasia↗

Antigenotoxicity of coffee in the Drosophila assay for somatic mutation and recombination.

The somatic mutation and recombination test (SMART) in Drosophila melanogaster was carried out to investigate whether or not coffee can modulate the genotoxicity of the well-established mutagenic/carcinogenic chemicals cyclophosphamide (CPH), diethylnitrosamine (DEN), mitomycin C (MMC), procarbazine (PRO) and urethane (URE). For this purpose, 3-day-old larvae, trans-heterozygous for the wing hair markers mwh (multiple wing hairs) and flr3 (flare3), were raised on instant medium containing either the genotoxin alone or in combination with instant coffee. From the results obtained, it was evident that the chronic co-administration of coffee was effective in significantly reducing the frequencies of single and twin spots induced by CPH, DEN, MMC and URE but not PRO. The maximum reduction was observed in the frequencies of twin spots (produced by mitotic recombination) after feeding larvae on medium containing coffee in combination with the compounds CPH or URE.

Animals↗

Coffee and tea intake and the risk of myocardial infarction.

The authors investigated the association of caffeinated coffee, decaffeinated coffee, and tea with myocardial infarction in a study of 340 cases and age-, sex-, and community-matched controls. The odds ratio for drinking > or = 4 cups/day of caffeinated coffee versus drinking < or = 1 cup/week was 0.84 (95% confidence interval (CI) 0.49-1.42) after adjustment for coronary risk factors (1 cup = 237 ml). The odds ratio for drinking > 1 cup/day of decaffeinated coffee versus nondrinkers was 1.25 (95% CI 0.76-2.04). For tea, the odds ratio for drinking > or = 1 cup/day versus nondrinkers was 0.56 (95% CI 0.35-0.90). In these data, only tea was associated with a lower risk of myocardial infarction.

Aged↗

Coffee and pancreatic cancer: an analysis of international mortality data.

This study assessed the relationship of per capita coffee imports and consumption, total dietary fat, saturated fat, cholesterol, tobacco, cigarettes, and national income for 1957-1965 to age-adjusted pancreatic cancer death rates of men and women from 22 countries in 1971-1974. With simple correlation analysis, coffee, total dietary fat, saturated fat, and national income were each significantly correlated with both male and female pancreatic cancer mortality. Bivariate partial correlation coefficients of coffee with pancreatic cancer mortality were significant (one-tailed) in 11 of 12 analyses and borderline significant in two-way analyses of variance (ANOVA) (two-tailed) controlling for each of the other variables. Saturated fat and pancreatic cancer were also significantly related in univariate analyses, and in 11 of 12 bivariate partial correlation analyses; in ANOVA, significance was borderline in 10 of 12 analyses. Total fat and pancreatic mortality were also significantly associated in most of the univariate and bivariate correlation analyses, but not in the two-way analyses of variance. The findings of this study are consistent with the hypothesis that coffee and dietary lipid are involved in the etiology of pancreatic cancer.

Adolescent↗

Alcohol, smoking, coffee, and cirrhosis.

Since most heavy drinkers do not develop alcoholic cirrhosis, other causes or predisposing factors are probable. The authors studied traits of 128,934 adults who underwent health examinations at the Oakland and San Francisco, California, facilities of the Kaiser Permanente Medical Care Program from January 1978 to December 1985 in relation to subsequent hospitalization or death from cirrhosis of the liver. In analyses adjusted for nine covariates, past and current alcohol drinking were strongly related to cirrhosis risk, but usual choice of alcoholic beverage had no independent relation. Cigarette smoking was independently related to risk of alcoholic cirrhosis, with cigarette smokers of a pack or more per day at trebled risk compared with lifelong nonsmokers. Coffee drinking, but not tea drinking, was inversely related to alcoholic cirrhosis risk, with persons who drank four or more cups per day at one-fifth the risk of noncoffee drinkers. This inverse relation between coffee consumption and risk of alcoholic cirrhosis was consistent in many subsets, including persons free of gastrointestinal disease and those with 5 or more years before hospitalization or death. Cigarette smoking and coffee consumption were not consistently related to risk of hospitalization or death for nonalcoholic cirrhosis. These data could mean that cigarette smoking promotes alcoholic cirrhosis and that coffee drinking might be protective.

Adult↗

Coffee and serum gamma-glutamyltransferase: a study of self-defense officials in Japan.

The relation of coffee drinking and other behavioral factors to serum gamma-glutamyltransferase (GGT) was examined in 2,494 male self-defense officials aged 48-56 years, who received a retirement health examination at the Self-Defense Forces Fukuoka Hospital between October 1986 and December 1990. Coffee, but not green tea, consumption was inversely related to serum GGT independently of body mass index, alcohol use, and smoking. All of the latter variables were also independently and positively associated with serum GGT. Lower levels of serum GGT associated with coffee drinking were more evident among heavier alcohol drinkers and also among heavier smokers. The findings suggest that coffee may inhibit the inducing effects of alcohol and possibly of smoking upon GGT in the liver.

Alcohol Drinking↗

Coffee and alcohol intake, smoking and risk of multiple pregnancy.

We analysed the relationship between coffee and alcohol intake, smoking and risk of multiple pregnancies using data from a case-control study on risk factors for multiple births conducted in Italy. Cases were 133 women who delivered multiple births not related to treatment for infertility (33 monozygotic and 100 dizygotic twins). Controls were 395 women admitted for normal delivery at the same clinic where cases had been identified. The odds ratios (OR) of multiple pregnancy were 1.5[95% confidence interval (CI) 0.8-2.8] and 2.0 (95% CI 1.0-3.7) for women drinking respectively one to two or three or more cups of coffee per day in comparison with non-coffee drinkers. Considering separately dizygotic and monozygotic pregnancies, the estimated OR were respectively for women drinking three or more cups of coffee, 1.7 and 3.1 for dizygotic and monozygotic pregnancies. The risk of multiple pregnancy tended to be higher in women drinking >or= 15 alcohol drinks per week: in comparison with tea-totallers the estimated OR for drink > or = 15 glasses per week were 2.3 and 2.6 respectively for dizygotic and monozygotic pregnancies. Heavy smokers (> or = 10 cigarettes per day) were at increased risk of multiple pregnancy: in comparison with never smokers, the estimated OR for multiple pregnancy was 1.6 (95% CI 0.9-2.7). Considering separately the two groups of multiple pregnancy, the OR of dizygotic and monozygotic pregnancy were 1.4 (95% CI 0.8-2.5) and 2.4 (95% CI 0.9-6.1) for women smoking > or = 10 cigarettes/day, but the trend in risk with number of cigarettes smoked per day and duration of the habit was not significant.

Adult↗

Caffeinated beverages, decaffeinated coffee, and spontaneous abortion.

We examined the relations between spontaneous abortion and the consumption of caffeine, individual caffeine-containing beverages (coffee, tea, and soda), and decaffeinated coffee in a prospective study of 5,144 pregnant women. We collected information about potential risk factors for spontaneous abortion, including consumption of caffeinated beverages and decaffeinated coffee before and during pregnancy, by interview in the first trimester. Neither total estimated caffeine nor individual caffeinated beverage consumption during the first trimester was associated with an appreciable increase in risk for spontaneous abortion. The adjusted odds ratio for consumption of greater than 300 mg per day of caffeine was 1.3 [95% confidence interval (CI) = 0.8-2.1] after adjustment for maternal age, pregnancy history, cigarette and alcohol consumption, employment, race, gestational age at interview, and marital and socioeconomic status. The adjusted odds ratio for spontaneous abortion related to consumption of three or more cups of decaffeinated coffee during the first trimester was 2.4 (95% CI = 1.3-4.7) in the same model. Although we could not demonstrate this with available data, we suspect that this association was due to bias resulting from the relations among fetal viability, symptoms of pregnancy such as nausea, and consumption patterns during pregnancy.

Abortion, Spontaneous↗

Blood pressure response to the "second cup of coffee".

Twenty young male coffee-drinkers consumed 150 mg of caffeine in decaffeinated coffee three times a day for 8 days. On days 3, 4, 7, and 8, caffeine or a placebo was administered in the laboratory at 11 A.M., 8 A.M., 11 A.M., and 8 A.M., respectively, in a randomized double-blind crossover design. There was a blood pressure increase relative to the placebo 45 min after taking caffeine at 8 A.M. (5.8/6.5 mm Hg). An increase of 2.4/5.2 mm Hg was seen with the second cup of coffee at 11 A.M. The lower the subject's pre-coffee serum caffeine level, the higher the systolic response, both at 8 A.M. (r = -0.60) and at 11 A.M. (r = -0.62). Because of the pressor effect resulting from habitual caffeine intake, the adverse implications of caffeine use should be considered.

Adolescent↗

The cardiovascular effects of regular and decaffeinated coffee.

In a single-blind study the effects of drinking two cups of regular or decaffeinated coffee on blood pressure, heart rate, forearm blood flow and plasma concentrations of caffeine, renin and catecholamines were studied in 12 normotensive subjects. Drinking regular coffee led to a rise of blood pressure, a fall of heart rate and an increase of plasma catecholamines. Decaffeinated coffee induced a smaller increase of diastolic blood pressure without changing other parameters. This study shows that the cardiovascular effects of drinking coffee are mainly the result of its caffeine content.

Adult↗

Coffee, coronary heart disease and mortality in middle-aged Swedish men: findings from the Primary Prevention Study.

The effect of coffee consumption on the incidence of coronary heart disease (CHD) was studied prospectively in a population sample of 6765 men aged 51-59 years at baseline during the period 1974-1977, and free of myocardial infarction (MI) prior to the screening. During a 7.1-year follow-up there were 230 non-fatal myocardial infarctions. 169 coronary deaths and 478 deaths from all causes. Among men who were smokers at baseline there was no relationship between either non-fatal MI or death from CHD, and coffee consumption. Among non-smokers, a weak but far from significant trend towards an increasing incidence of CHD in heavy consumers of coffee was observed. There was an inverse relationship between mortality from all causes and coffee consumption.

Coffee↗