Evaluation of the teratogenic potential of fresh-brewed coffee and caffeine in the rat.
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Abnormalities, Drug-Induced↗
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Coffee consumption and serum lipids: a randomized, crossover clinical trial.
PURPOSE: The purpose of this study was to determine the effect of consuming three or more cups of filter-brewed coffee per day on levels of serum lipids. SUBJECTS AND METHODS: A prospective, randomized crossover clinical trial was performed. Twenty-one healthy white male subjects completed the trial, and consumed an average of 3.6 cups of coffee a day. Data were evaluated by analysis of variance for repeated measures and t-test for paired means. RESULTS: No effect of coffee consumption on serum total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, or apolipoprotein B was found. Diet, creamer use, and cigarette use as well as group assignment and time factors were controlled for in the analysis. CONCLUSION: We found no effect of moderate consumption of filter-brewed coffee on serum levels of atherogenic lipids. This study supports previous work that filtered coffee has no adverse effect on serum lipids. This has far-reaching implications given the widespread use of coffee and the current concern over coronary risk factors.
Adult↗
Coffee consumption and blood pressure: a randomized, crossover clinical trial.
OBJECTIVE: To examine the effect of moderate coffee consumption on blood pressure over a prolonged period of time. Previous work in this area has used primarily purified caffeine. DESIGN: A prospective, randomized, crossover clinical trial. SETTING: A hypertension specialty outpatient clinic at the University of Tennessee, Memphis. PATIENTS: Healthy, young, white men who were moderate coffee drinkers (less than 6 cups/day) were recruited. Twenty-four subjects were randomized and 21 (average age 35.5 years) completed the trial. INTERVENTIONS: Subjects were randomized to one of two groups: Group A drank three or more cups of coffee/day for two months, then crossed over to abstaining from coffee for two months; group B abstained from coffee first, then crossed over to drinking coffee. Only filter-brewed coffee was used. Subjects were seen at monthly intervals for blood pressure measurements. MEASUREMENTS AND MAIN RESULTS: The average coffee consumption was 3.6 cups/day during the coffee-drinking phases. There was no difference between the coffee-drinking phase and the abstention phase in either systolic blood pressure (110.1 mmHg vs. 108.0 mmHg, respectively; 95% CI of difference -7.3, 2.5) or diastolic blood pressure (67.2 mmHg vs. 69.6 mmHg, respectively; 95% CI of difference -2.2, 6.4). CONCLUSIONS: Moderate daily consumption of coffee does not elevate blood pressure.
Adult↗
Furanic compounds in different coffee extraction systems: Analysis of the main influencing factors and correlation with acrylamide.
This study investigates how different coffee types representative of distinct roast profiles and brewing methods jointly affect the occurrence of furanic compounds and acrylamide in brewed coffee. Coffees were prepared using eight extraction methods (AeroPress, Clever, Chemex, French Press, Moka, Pure Brew, Turkish and V60). Five furanic compounds (furfural, furfuryl acetate, 5-methylfurfural, furfuryl alcohol and 5-hydroxymethylfurfural) were quantified in coffee powders and brews by HS-SPME-GC-MS, while acrylamide was determined by UHPLC-MS/MS. Moka and Turkish brews consistently exhibited the highest concentrations of furanic compounds, whereas paper-filtered pour-over methods (V60 and Chemex) showed the lowest levels. Pearson correlation analysis revealed coffee-dependent relationships between furanic compounds, acrylamide and extraction parameters with the strongest associations observed in dark-roasted coffee, reflecting advanced Maillard reaction chemistry. Overall, these results demonstrate that contaminant levels arise from the combined effects of intrinsic coffee chemistry and brewing mechanics and support targeted mitigation strategies: such as roast selection and brewing method optimization.
Acrylamide↗
[Studies of coffee and coffee-substitute. XVIII. Dependence of the quantity and composition of a high polymer galactomannan on the coffee species and degree of roasting (authors transl)].
It is possible to determine quantitatively with satisfactory accuracy the galactomannan which is precipitated in coffee brew after addition of Fehling solution. The content of polysaccharides in the extracts increases with the degree of roasting. Galactomannan makes up 6.6 to 12.7% of the dry matter of the extracts and 1.8 to 4.4% of that of roast coffee. It consists mainly of mannan, to a much smaller degree of galactan. Often there are traces of glucan. The content of mannan increases with the degree of roasting while that of galactan decreases very rapidly.
Coffee↗
Caffeine effects on meiotic maturation in hamster oocytes in vitro.
The effect of caffeine on meiotic maturation in cultured hamster oocytes was investigated. Meiotic status was scored from chromatin spreads of oocytes previously exposed to caffeine (0, 0.00017, 0.0017, 0.017, 0.17, 1.7, 2.4, 5.1, and 10.2 mM) for up to 20 h. While concentrations of caffeine less than 0.017 mM failed to affect significantly the onset of meiotic resumption, 0.0017 mM caffeine significantly decreased the proportion of oocytes progressing normally to telophase I-metaphase II, and concomitantly increased the proportion of both diploid MII and aneuploid oocytes. In addition, 0.17 to 10.2 mM caffeine induced a dose-dependent increase in the proportion of meiotically arrested oocytes, with less than 5% oocytes progressing normally through to the final stages of meiotic maturation at 10.2 mM caffeine. Taken together, these data show that caffeine at concentrations as low as 0.0017 to 0.017 mM interfere with progression of meiotic maturation, and that concentrations higher than 0.017 mM delay initiation of this process. Since caffeine peaks at 0.017 mM in the plasma of women following a cup of brewed coffee, we conclude that caffeine-induced perturbations of oocyte meiotic maturation may be responsible, at least in part, for the recently revealed correlation between caffeine intake and reduced fertility in women.
Animals↗
Failure of caffeine to affect metabolism during 60 min submaximal exercise.
Caffeine consumption prior to athletic performance has become commonplace. The usual dosage is approximately 200 mg, a level of caffeine ingestion equivalent to two cups of brewed coffee. This study was designed to examine the effects of a common level of caffeine ingestion, specifically 200 mg, on metabolism during submaximal exercise performance in five males. The subjects performed two 60-min monitored treadmill workouts at 60% maximal heart rate during a 2-week period. The subjects were randomly assigned, double-blind to receive a caffeine or placebo capsule 60 min prior to exercise. Testing was performed in the afternoon following a midnight fast. Venous blood was withdrawn pre-exercise, every 15 min during the workout, and 10 min after recovery. Blood was analysed for free fatty acid, triglycerides, glucose, lactic acid, haemoglobin and haematocrit. The respiratory exchange ratio (R), perceived exertion (RPE) and oxygen uptake were measured every 4 min during exercise. An examination of the data with repeated-measures ANOVA revealed no significant differences between the two groups. Within the limitations of the study, it was concluded that 200 mg caffeine failed to affect metabolism during 60 min submaximal exercise.
Adult↗
Low-dose caffeine physical dependence in humans.
This study investigated the effects of terminating low dose levels of caffeine (100 mg/day) in 7 normal humans. Substitution of placebo capsules for caffeine capsules occurred under double-blind conditions while subjects rated various dimensions of their mood and behavior. In the first phase of the study, substitution of placebo for 12 consecutive days resulted in an orderly withdrawal syndrome in 4 subjects which peaked on days 1 or 2 and progressively decreased toward prewithdrawal levels over about 1 week. Data from the remaining three subjects provided no evidence of withdrawal. In the second phase of the study, the generality of the withdrawal effect was examined by repeatedly substituting placebo for 100 mg/day of caffeine for 1-day periods separated by an average of 9 days. Despite differences within and across subjects with respect to the presence, nature and magnitude of symptoms, each of the seven subjects demonstrated a statistically significant withdrawal effect. Although the phenomenon of caffeine withdrawal has been described previously, the present report documents that the incidence of caffeine withdrawal is higher (100% of subjects), the daily dose level at which withdrawal occurs is lower (roughly equivalent to the amount of caffeine in a single cup of strong brewed coffee or 3 cans of caffeinated soft drink) and the range of symptoms experienced is broader (including headache, fatigue and other dysphoric mood changes, muscle pain/stiffness, flu-like feelings, nausea/vomiting and craving for caffeine) than heretofore recognized.
Adult↗
Caffeine content of common beverages.
Tea, coffee, carbonated and chocolate beverages were analyzed for caffeine, and results compared in terms of usual serving sizes. Significant differences in caffeine levels were found to result from the preparation method of coffee or brewing time of tea. It is possible for a cup of tea, instant coffee, or can of cola beverage to have similar caffeine content (55 to 65 mg.); however, the mean values per cup of black tea (28 to 46 mg.) are considerably lower than for brewed coffee (107 to 151 mg.). Caffeine is readily absorbed and can have pharmacologic effects on adults or on children who consume quantities of cola beverages or chocolate. Both preparation method and quantity of beverage consumed should be considered in taking dietary histories or estimating caffeine intake.
Beverages↗
Coffee drinking and blood cholesterol--effects of brewing method, food intake and life style.
The strongest correlations between coffee consumption and serum cholesterol levels have been found in countries where people drink coffee brewed by mixing coffee grounds directly in boiling water (boiled coffee). In the present study of a population-based sample of 1625 middle-aged subjects (the Northern Sweden MONICA Study), approximately 50% of the participants were drinking boiled coffee, and 50% were drinking filtered coffee. Consumers of boiled coffee had significantly higher serum cholesterol levels than consumers of filtered coffee. Subjects who drank boiled coffee reported a higher intake of fat. A linear multiple regression analysis with serum cholesterol as the dependent variable confirmed that boiled coffee was an important independent determinant of cholesterol levels. We conclude that subjects who drink boiled coffee have higher serum cholesterol levels than those who drink filtered coffee, and that the most likely explanation for this finding lies in the type of brewing method.
Adult↗
Coffee and cholesterol: what is brewing?
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Cholesterol↗
Loss of heterocyclic amine mutagens by insoluble hemicellulose fiber and high-molecular-weight soluble polyphenolics of coffee.
The presence of 2 kinds of components in brewed and instant coffee that could remove and destroy heterocyclic amine mutagens was demonstrated. The component that could remove the mutagens was insoluble fiber composed of hemicellulose. The fiber could tightly adsorb the mutagens Trp-P-1, Trp-P-2, Glu-P-1 and A alpha C, and those generated in roasted coffee beans. The component that could destroy the mutagens was high-molecular-weight soluble polyphenolics. They might be converted into quinone derivatives in the presence of molecular oxygen. The quinone derivatives might destroy the mutagens. The fibers and the polyphenolics in one cup of brewed or instant coffee had the capacity to remove and destroy a substantial amount of the mutagens in pyrolysates of foodstuffs.
Amines↗
Coffee drinking and cancer of the lower urinary tract.
The relationship between coffee drinking and cancer of the lower urinary tract (LUT) was investigated by a case-control study of white women identified from hospitals in urban areas of Massachusetts and Rhode Island. Data on coffee drinking, tea drinking, use of coffee additives, and cigarette smoking were obtained by mail questionnaire. Information was available for 135 women with LUT cancer and 390 controls. For women who usually drank 1+ cups of coffee per day, the risk ratio of having LUT cancer was 2.1 (95 percent confidence limits, 1.1-4.3), compared to a risk of 1 for women who drank less or not at all. However, no dose-response relationship was demonstrated between LUT cancer and usual daily coffee consumption or "cup-years" of coffee drinking. The association of coffee with disease was no different, whether decaffeinated, nondecaffeinated, regular, or instant coffee had been drunk, or whether the coffee was brewed strong or weak. Use of nondairy creamers, saccharin, or cyclamates was not associated with increased risk of disease. The risk of LUT cancer for cigarette smokers relative to nonsmokers was 1.6 (1.0-2.4). The attendant dose-response relationship was statistically significant. The absence of a dose-response relationship between coffee drinking and LUT cancer suggested that the association observed was noncasual.
Aged↗
Boiled coffee and blood pressure. A 14-week controlled trial.
The question of whether long-term elimination of coffee from the diet lowers blood pressure has not been settled. Consumption of Scandinavian-style "boiled coffee" is associated with coronary heart disease. However, little is known about the effect of brewing method on the blood pressure-raising potential of coffee. We have studied the effects on blood pressure and heart rate of total elimination of coffee and tea in comparison with drinking boiled coffee consumed as such, or boiled coffee consumed after filtration through paper filter. Thirty-one women and 33 men first consumed 6 cups/day of boiled and filtered coffee for 17 days. Then they were randomly divided into three groups, which for the next 79 days received either unfiltered boiled coffee (caffeine content 860 mg/l), boiled-and-filtered coffee (887 mg caffeine/l), or no coffee, the latter being replaced by fruit juice and mineral water. Total elimination of coffee did not significantly affect blood pressure or heart rate relative to boiled-and-filtered coffee. In subjects who drank boiled coffee, mean ambulant systolic blood pressure rose significantly relative to those who consumed boiled-and-filtered coffee (mean difference +/- SEM, 3.1 +/- 1.1 mm Hg, p = 0.006). This response showed a tendency to be stronger for women (4.5 +/- 1.8 mm Hg) than for men (1.7 +/- 1.2 mm Hg). We conclude that elimination of filtered coffee has no substantial long-term effect on blood pressure, but consumption of unfiltered boiled coffee may cause a slight but significant rise in systolic blood pressure.
Adult↗
Coffee and cholesterol, an Italian study.
In the present study, conducted in northern Italy between 1986 and 1989, the authors investigated the possible association between coffee consumption and serum cholesterol levels in 8,983 subjects, 7,432 men and 1,551 women, managers and employees aged 18-65 years, who were examined during a program of preventive medicine upon an agreement between various companies and the Centro Diagnostico Italiano. Analysis of covariance was used to compare the serum cholesterol levels of the subjects subdivided according to coffee consumption, along with age, body mass index, alcohol consumption, cigarette smoking, and physical activity. An important relation was demonstrated between coffee intake and cholesterol, particularly in the men, the differences in serum cholesterol in the coffee users compared with the nonusers being 6.1 +/- 1.4 (standard error) mg/dl for consumers of 1-3 cups/day (3.4 +/- 1.4 mg/dl after adjustment for age, body mass index, alcohol and cigarette consumption, and physical activity), 9.9 +/- 1.6 mg/dl for those drinking 4-5 cups/day (5.8 +/- 1.6 mg/dl after adjustment), and 14.8 +/- 2.0 mg/dl for those drinking over 5 cups/day (9.6 +/- 2.0 mg/dl after adjustment). This relation remained substantially unvaried when nonsmokers and smokers were analyzed separately. It has been suggested that it is coffee prepared by boiling rather than other methods that has a hypercholesterolemic effect. Our observations demonstrate an interesting relation between coffee and cholesterol, even though the coffee drunk in Italy is mainly filtered and nonboiled. However, our finding is not necessarily in disagreement with the above hypothesis since, when coffee is prepared in the Italian way (with the mocha method), ground coffee is preheated by steam and more importantly, the water passes through the ground coffee at a higher temperature than with the other brewing methods.
Adolescent↗
A study of caffeine in tea. I. A new spectrophotometric micro-method. II. Concentration of caffeine in various strengths, brands, blends, and types of teas.
A new spectrophotometric micro-method for the determination of caffeine in tea is described. This method is then used to evaluate the caffeine content of a variety of brands and blends of bagged and loose hot tea prepared in different strengths and by different brewing methods. In addition, the caffeine content of instant tea, ice tea, and Mr. Coffee automatic tea is evaluated.
Caffeine↗
The science of Arabic coffee (Qahwa): from phytochemistry and nutritional profile to health benefits and safety evaluation.
Arabic coffee (Qahwa), a traditional beverage widely consumed in the Middle East, has attracted increasing scientific attention due to its distinctive phytochemical composition and associated health effects. This review provides an integrated analysis of Qahwa's nutritional profile, focusing on its key bioactive constituents, including chlorogenic acids, caffeine, diterpenes (cafestol and kahweol), and phenolic compounds. These constituents contribute to a range of biological activities, notably antioxidant, anti-inflammatory, hepatoprotective, and metabolic regulatory effects. The influence of technological variables, including roasting degree, brewing method, and bean origin, on the chemical composition and functional properties is critically examined. Safety concerns, particularly acrylamide formation and mycotoxin contamination, are also discussed. Although emerging data support Qahwa's potential as a functional beverage, further research is required to clarify dose-response relationships, synergistic interactions, and long-term health outcomes. This work highlights Qahwa as a promising candidate for food and nutraceutical applications, warranting standardized compositional profiling and toxicological evaluation.
Humans↗