Caffeine and blood pressure response: sex, age, and hormonal status

The effects of caffeine supplementation on blood pressure in adults: A systematic review and dose-response meta-analysis

BACKGROUND AND AIMS

Hypertension is a serious complication linked to a higher risk for organs. Caffeine is a natural component that affects the cardiovascular system, while the mechanisms of its effects are not fully established. Therefore, we aimed to examine the impact of caffeine supplementation on blood pressure (BP) by conducting a systematic review and dose-response meta-analysis of randomized controlled clinical trials (RCTs).

METHODS AND RESULTS

We searched online databases using relevant keywords up to July 2022 to identify RCTs using caffeine on systolic (SBP) and diastolic BP (DBP) in adults. Inclusion criteria were adult participants ≥18 years old for subjects, examining the effect of caffeine supplementation on BP, and RCTs studies. A random-effects model was used to estimate the weighted mean difference (WMD) and 95% confidence (CI). The pooled of 11 effect sizes analysis of 8 studies demonstrated significant increases in SBP (WMD:1.94 mmHg; 95%CI:0.52, 3.35; p = 0.007) and DBP (WMD:1.66 mmHg; 95% CI:0.75, 2.57; p = 0.000) after caffeine supplementation. The subgroup analysis showed that caffeine supplementation more effectively increased SBP and DBP in males than females. Moreover, meta-regression analysis demonstrated a significant relationship between the dose of caffeine intake and changes in SBP (p = 0.000), DBP (p = 0.000), and duration of the trial in SBP (p = 0.005), and DBP (p = 0.001). The non-linear dose-response analysis detected the dosage of supplementation >400 mg/day is effective for increasing DBP (p = 0.034), and the duration of supplementation of more than nine weeks makes increasing in both SBP and DBP.

CONCLUSION

This meta-analysis shows that caffeine supplementation significantly increased SBP and DBP in adults.

Prevalence of caffeine consumers, daily caffeine consumption, and factors associated with caffeine use among active duty United States military personnel

Background

Although representative data on caffeine intake in Americans are available, these data do not include US service members (SMs). The few previous investigations in military personnel largely involve convenience samples. This cross-sectional study examined prevalence of caffeine consumers, daily caffeine consumption, and factors associated with caffeine use among United States active duty military service members (SMs).

Methods

A stratified random sample of SMs were asked to complete an on-line questionnaire on their personal characteristics and consumption of caffeinated products (exclusive of dietary supplements). Eighteen percent (n = 26,680) of successfully contacted SMs (n = 146,365) completed the questionnaire.

Results

Overall, 87% reported consuming caffeinated products ≥1 time/week. Mean ± standard error per-capita consumption (all participants) was 218 ± 2 and 167 ± 3 mg/day for men and women, respectively. Caffeine consumers ingested 243 ± 2 mg/day (251 ± 2 mg/day men, 195 ± 3 mg/day women). On a body-weight basis, men and women consumed respectively similar caffeine amounts (2.93 vs 2.85 mg/day/kg; p = 0.12). Among individual caffeinated products, coffee had the highest use (68%), followed by sodas (42%), teas (29%), energy drinks (29%) and gums/candy/medications (4%). In multivariable logistic regression, characteristics independently associated with caffeine use (≥1 time/week) included female gender, older age, white race/ethnicity, higher body mass index, tobacco use or former use, greater alcohol intake, and higher enlisted or officer rank.

Conclusion

Compared to National Health and Nutrition Examination Survey data, daily caffeine consumption (mg/day) by SMs was higher, perhaps reflecting higher mental and physical occupational demands on SMs.

Effect of Caffeinated and Decaffeinated Coffee on Blood Pressure and Heart Rate of Healthy Individuals

<b>Background and Objective:</b> Caffeine is the most widely consumed stimulant in the world with 80% of it consumed in the form of coffee. It is used as an ingredient in pharmaceuticals, owing to the high content of nutrients and antioxidants, including phenols and polyphenols, that have cardioprotective properties. This study aimed to investigate and compare the effects of caffeinated and decaffeinated coffee on blood pressure and heart rate. <b>Materials and Methods:</b> In this study, experimental days were divided over 2 weeks: February 21 to March 6. Each week, the participants were provided with a specific type of coffee to drink. They were advised to avoid exercise and vigorous physical activity and to get enough sleep. Blood pressure and heart rate were measured in resting/sitting position from the left arm using a blood pressure device, OMRON Model BP5100. The participants were clear of any cardiovascular diseases or hypertension. Any participants, who suffered from hypertension or hypotension were excluded. <b>Results:</b> We compared the impact of coffee with caffeine and without caffeine on systolic and diastolic blood pressure and heart rate. No difference in heart rates or blood pressure was observed in participants after 30-90 min of drinking either caffeinated or decaffeinated coffee. <b>Conclusion:</b> Based on the tests performed on 40 participants, we conclude that there are no significant differences in the influence of either type of coffee on blood pressure or heart rate.

Leveraging vibration of effects analysis for robust discovery in observational biomedical data science

Hypothesis generation in observational, biomedical data science often starts with computing an association or identifying the statistical relationship between a dependent and an independent variable. However, the outcome of this process depends fundamentally on modeling strategy, with differing strategies generating what can be called "vibration of effects" (VoE). VoE is defined by variation in associations that often lead to contradictory results. Here, we present a computational tool capable of modeling VoE in biomedical data by fitting millions of different models and comparing their output. We execute a VoE analysis on a series of widely reported associations (e.g., carrot intake associated with eyesight) with an extended additional focus on lifestyle exposures (e.g., physical activity) and components of the Framingham Risk Score for cardiovascular health (e.g., blood pressure). We leveraged our tool for potential confounder identification, investigating what adjusting variables are responsible for conflicting models. We propose modeling VoE as a critical step in navigating discovery in observational data, discerning robust associations, and cataloging adjusting variables that impact model output.

The Effects of Interrupting Prolonged Sitting With Frequent Bouts of Light-Intensity Standing Exercises on Blood Pressure in Stroke Survivors: A Dose Escalation Trial

BACKGROUND

Interrupting prolonged sitting acutely lowers blood pressure in nonstroke populations. However, the dose-response effect in stroke survivors is unknown. The authors investigated different doses of light-intensity standing exercises that interrupt prolonged sitting and reduce blood pressure immediately and over 24 hours in stroke survivors.

METHODS

Within-participant, laboratory-based, dose escalation trial. Conditions (8 h) were prolonged sitting and 2 experimental conditions of standing exercises with increasing frequency (3 cohorts, 2 × 5 min to 6 × 5 min). The primary outcome is the mean systolic blood pressure.

RESULTS

Twenty-nine stroke survivors (aged 66 [12] y) participated. Frequent bouts of standing exercises lowered the mean systolic blood pressure following the 4 × 5-minute (-2.1 mm Hg; 95% confidence interval [CI], -3.6 to -0.6) and 6 × 5-minute conditions (-2.3 mm Hg; 95% CI, -4.2 to -0.5) compared with prolonged sitting. Diastolic blood pressure was lowered following the 6 × 5-minute condition (-1.4 mm Hg; 95% CI, -2.7 to -0.2). The 24-hour systolic blood pressure increased following the 2 × 5-minute condition (6.9 mm Hg; 95% CI, 3.1 to 10.6).

CONCLUSIONS

Interrupting prolonged sitting with more frequent bouts of standing exercises lowers systolic and diastolic blood pressure in stroke survivors. However, reductions may only be short term, and investigations on sustained effects are warranted.

Caffeine ingestion alters central hemodynamics following aerobic exercise in middle-aged men

PURPOSE

To examine the acute influence of caffeine on post-exercise central blood pressures, arterial stiffness, and wave reflection properties.

METHODS

In a double-blind randomized placebo-controlled crossover study design, ten middle-aged males (55 ± 5 year) completed two exercise trials after ingestion of caffeine (400 mg) or placebo. Measurements were taken before and 30 min post-ingestion via cuff-based pulse wave analysis (PWA) and carotid-femoral pulse wave velocity (PWV). Participants performed a 40-min cycling bout at 70% HRmax with matched workloads between trials. PWA and PWV were reassessed 30 min post-exercise.

RESULTS

Prior to exercise, compared to placebo, caffeine increased brachial systolic blood pressure (bSBP) (+ 12.3 ± 2.4 mmHg; p = 0.004), brachial diastolic blood pressure (bDBP) (+ 7.7 ± 0.9 mmHg; p = 0.011), central systolic blood pressure (cSBP) (+ 11.1 ± 2.1 mmHg; p = 0.005) and central diastolic blood pressure (cDBP) (+ 7.6 ± 1.0 mmHg; p = 0.012). PWV was higher 30 min after pill ingestion (p = 0.021 for time) with a trend for a greater increase in caffeine (p = 0.074 for interaction). bSBP (p = 0.036) and cSBP (p = 0.007) were lower after exercise but remained higher (both p < 0.001) in caffeine compared to placebo. PWV remained higher (p = 0.023) after exercise in caffeine compared to placebo but was not influenced by exercise. At rest, augmentation pressure (AP) and index (AIx) were not influenced by caffeine ingestion. Conversely, AIx was lower (p = 0.009) after exercise in placebo only.

CONCLUSION

In healthy and active middle-aged men, pre-exercise caffeine ingestion led to higher central and peripheral systolic blood pressures, PWV and AIx at 30 min post-exercise, indicating an increased left ventricular workload which may have implications for cardiovascular event risk.

Bioactive Compounds and Their Effect on Blood Pressure-A Review

Elevated blood pressure affects a great part of the elderly population and is the leading risk factor for cardiovascular disease. New approaches have been taken in the fight against this growing problem, in the form of diets (Mediterranean, Dietary Approaches to Stop Hypertension (DASH) and intermittent fasting). Recent research has shown the promising results regarding diets and their effect on the prevention and improvement of elevated blood pressure. This review attempts to take this a step further, reviewing 26 studies in the search for dietary elements that may be causing this improvement. Although good evidence was found in favor of lycopene, Docosahexaenoic acid (DHA), fiber and anthocyanin, further evidence is needed before any conclusions can be made. In contrast, the evidence shows that licorice increases blood pressure.

Quantile-Specific Heritability may Account for Gene-Environment Interactions Involving Coffee Consumption

Estimated heritability of coffee intake ranges from 0.36 to 0.58, however, these point estimates assume that inherited effects are the same throughout the distribution of coffee intake, i.e., whether consumption is high or low relative to intake in the population. Quantile regression of 4788 child-parent pairs and 2380 siblings showed that offspring-parent and sibling concordance became progressively greater with increasing quantiles of coffee intake. Each cup/day increase in the parents' coffee intake was associated with an offspring increase of 0.020 ± 0.013 cup/day at the 10th percentile of the offsprings' coffee intake (slope ± SE, NS), 0.137 ± 0.034 cup/day at their 25th percentile (P = 5.2 × 10^-5), 0.159 ± 0.029 cup/day at the 50th percentile (P = 5.8 × 10^-8), 0.233 ± 0.049 cup/day at the 75th percentile (P = 1.8 × 10^-6), and 0.284 ± 0.054 cup/day at the 90th percentile (P = 1.2 × 10^-7). This quantile-specific heritability suggests that factors that distinguish heavier vs. lighter drinkers (smoking, male sex) will likely manifest differences in estimated heritability, as reported.

Caffeine Consumption through Coffee: Content in the Beverage, Metabolism, Health Benefits and Risks

Caffeine (1,3,7-trimethylxanthine) is the most consumed psychoactive substance in the world, acting by means of antagonism to adenosine receptors, mainly A1 and A2A. Coffee is the main natural source of the alkaloid which is quite soluble and well extracted during the brew’s preparation. After consumption, caffeine is almost completely absorbed and extensively metabolized in the liver by phase I (cytochrome P450) enzymes, mainly CYP1A2, which appears to be polymorphically distributed in human populations. Paraxanthine is the major caffeine metabolite in plasma, while methylated xanthines and methyluric acids are the main metabolites excreted in urine. In addition to stimulating the central nervous system, caffeine exerts positive effects in the body, often in association with other substances, contributing to prevention of several chronic diseases. The potential adverse effects of caffeine have also been extensively studied in animal species and in humans. These aspects will be approached in the present review.

Caffeine and blood pressure: a critical review perspective

The WHO reported that high blood pressure (BP) is one of the primary causes of death worldwide. Hypertension (HPT) is a major risk factor for CVD and related diseases as well as for diseases, leading to a considerable increase in cardiovascular risk. Since BP response could also be influenced by caffeine, which is widely consumed with coffee and other items, it is important to define the possible effects associated with caffeine intake. The most recent findings aimed at clarifying the role of caffeine consumption on BP and HPT risk/incidence are conflicting and difficult to interpret. Therefore, in the present narrative review, we aimed to examine various methodological inaccuracies/aspects and factors that make studies difficult to be compared, in order to obtain a single consensus on the effects of caffeine intake on the risk of BP and HPT. We observed that this heterogeneity in results could be due to the presence of: (i) several variables affecting BP (such as age, sex, genetic and lifestyle aspects); (ii) different caffeine content of food and beverages; and (iii) caffeine metabolism. Moreover, different methodological aspects in the evaluation of daily dietary caffeine intake and in the BP measurement could add some other bias in the interpretation of results. Therefore, it is mandatory to consider all methodological aspects and confounding factors to generate a standardised methodology in order to increase cross-study consistency and minimise confounding effects of different variables on the relationship between BP response and HPT risk/incidence after caffeine intake.

Cardiovascular and Metabolic Responses to the Ingestion of Caffeinated Herbal Tea: Drink It Hot or Cold?

Aim: Tea is usually consumed at two temperatures (as hot tea or as iced tea). However, the importance of drink temperature on the cardiovascular system and on metabolism has not been thoroughly investigated. The purpose of this study was to compare the cardiovascular, metabolic and cutaneous responses to the ingestion of caffeinated herbal tea (Yerba Mate) at cold or hot temperature in healthy young subjects. We hypothesized that ingestion of cold tea induces a higher increase in energy expenditure than hot tea without eliciting any negative effects on the cardiovascular system.

Methods: Cardiovascular, metabolic and cutaneous responses were analyzed in 23 healthy subjects (12 men and 11 women) sitting comfortably during a 30-min baseline and 90 min following the ingestion of 500 mL of an unsweetened Yerba Mate tea ingested over 5 min either at cold (~3°C) or hot (~55°C) temperature, according to a randomized cross-over design.

Results: Averaged over the 90 min post-drink ingestion and compared to hot tea, cold tea induced (1) a decrease in heart rate (cold tea: −5 ± 1 beats.min⁻¹; hot tea: −1 ± 1 beats.min⁻¹, p < 0.05), double product, skin blood flow and hand temperature and (2) an increase in baroreflex sensitivity, fat oxidation and energy expenditure (cold tea: +8.3%; hot tea: +3.7%, p < 0.05). Averaged over the 90 min post-drink ingestion, we observed no differences of tea temperature on cardiac output work and mean blood pressure responses.

Conclusion: Ingestion of an unsweetened caffeinated herbal tea at cold temperature induced a greater stimulation of thermogenesis and fat oxidation than hot tea while decreasing cardiac load as suggested by the decrease in the double product. Further experiments are needed to evaluate the clinical impact of unsweetened caffeinated herbal tea at a cold temperature for weight control.

The acute effect of black tea consumption on resistance artery endothelial function in healthy subjects. A randomized controlled trial

BACKGROUND & AIMS

Black tea is a main source of flavonoids in the Western diet and has been associated with reduced risk for cardiovascular disease, possibly through lowering blood pressure. These effects may be mediated through improving endothelial function of resistance arteries. The aim of this study was therefore to examine the acute impact of black tea on forearm resistance artery endothelial function in healthy, normotensive middle-aged subjects.

METHODS

Twenty middle-aged men and women (age-range 45-75 years) were recruited into a double-blind, randomized, placebo-controlled crossover intervention study. Forearm resistance artery blood flow (FBF, measured using venous occlusion plethysmography) in response to incremental doses of acetylcholine, sodium nitroprusside and L-N^G-monomethyl arginine were determined 2 h after consumption of either black tea containing ∼400 mg flavonoids (equivalent to 2-3 cups of tea) or a taste- and color-matched placebo.

RESULTS

The mean FBF-response to acetylcholine after tea consumption was 23% higher compared to the response after placebo (95% CI: -20%, +88%), but this difference did not reach statistical significance (P = 0.32). No significant differences in the FBF-responses to sodium nitroprusside and L-N^G-monomethyl arginine were found between the tea and placebo interventions (P = 0.96 and 0.74, respectively). Correcting FBF for changes in blood pressure did not alter the outcomes.

CONCLUSIONS

We found no evidence that acute intake of black tea significantly altered endothelium-dependent vasodilation of forearm resistance arteries in healthy middle-aged subjects. Interventions with a longer duration of tea ingestion are required to further explore the (long-term) impact of tea flavonoids on blood pressure regulatory mechanisms. This trial was registered at clinicaltrials.gov as NCT02328339.

Metabolic syndrome in menopause and associated factors: a meta-analysis

OBJECTIVE

Metabolic syndrome (MetS) is a cluster of risk factors for cardiovascular disease and diabetes. Menopause is associated with an increased risk for MetS. The purpose of this meta-analysis is to better understand the relationship between MetS and menopause.

METHODS

MEDLINE and EMBASE were searched for all the associated articles on (1) MetS components in postmenopausal women vs. premenopausal women, (2) comparison of MetS incidence between surgical menopause and natural menopause, (3) the effect of hormone therapy (HT) with 17β-estradiol (E2) compared to conjugated equine estrogen (CEE) on MetS components among postmenopausal women. A meta-analysis was applied by Review Manager 5.3 software.

RESULTS

All comparable indicators were significantly unfavorably changed in postmenopausal women compared to premenopausal women except for high density lipoprotein cholesterol. Women who underwent surgical menopause suffered a 1.51-fold higher risk for MetS compared to those with natural menopause. HT with E2 provided more benefits for levels of triglyceride and diastolic blood, while CEE showed a better effect on both high and low density lipoprotein cholesterol levels.

CONCLUSIONS

Menopause nearly adversely affects all components of MetS, and surgical menopause may lead to a higher incidence of MetS compared to natural menopause. HT with various preparations may have different effects on MetS components. These results may clarify the management of menopause-related MetS in clinical practice.

Coffee consumption and disease correlations

Coffee is one of the most widely consumed beverages in the world. It has primarily consumed due to its stimulant effect and unique taste since the ancient times. Afterwards, its consumption has been historically associated with a lower risk of some diseases such as type 2 diabetes mellitus, obesity, cardiovascular disease and some type of cancer and thus it has also consumed due to health benefits. It contains many bioactive compounds such as caffeine, chlorogenic acids and diterpenoid alcohols which have so far been associated with many potential health benefits. For example, caffeine reduces risk of developing neurodegenerative disease and chlorogenic acids (CGA) and diterpene alcohols have many health benefits such as antioxidant and chemo-preventive. Coffee also have harmful effects. For example, diterpenoid alcohols increases serum homocysteine and cholesterol levels and thus it has adverse effects on cardiovascular system. Overall, the study that supports the health benefits of coffee is increasing. But, it is thought-provoking that the association with health benefits of coffee consumption and frequency at different levels in each study. For this reason, we aimed to examine the health effect of the coffee and how much consumption is to investigate whether it meets the claimed health benefits.

Effect of Caffeine on near Maximal Blood Pressure and Blood Pressure Recovery in Physically-Active, College-Aged Females

The purpose of this study is to determine how caffeine affects exercise blood pressure (BP) and active and passive recovery BP after vigorous intensity exercise in physically active college-aged females. Fifteen physically active, ACSM stratified low-risk females (age (y): 23.53 ± 4.07, weight (kg): 60.34 ± 3.67, height (cm): 165.14 ± 7.20, BMI (kg/m²): 22.18 ± 1.55) participated in two Bruce protocol exercise tests. Before each test participants consumed 1) a placebo or 2) 3.3 mg·kg^-1 of caffeine at least one hour before exercise in a counterbalanced double-blinded fashion. After reaching 85% of their age-predicted maximum heart rate, BP was taken and participants began an active (i.e. walking) recovery phase for 6 minutes followed by a passive (i.e. sitting) recovery phase. BP was assessed every two minutes in each phase. Recovery times were assessed until active and passive BP equaled 20 mmHg and 10 mmHg above resting, respectively. Participants completed each test 1-2 weeks a part. Maximal systolic and diastolic blood pressures were not significantly different between the two trials. Active recovery, passive recovery, and total recovery times were all significantly longer during the caffeine trial than the placebo trial. Furthermore, the time to reach age-predicted maximum heart rate was significantly shorter in the placebo trial than the caffeine trial. While caffeine consumption did not significantly affect maximal blood pressure, it did affect active and passive recovery time following vigorous intensity exercise in physically active females. Exercise endurance also improved after consuming caffeine in this population.

Caffeine Use among Active Duty Navy and Marine Corps Personnel

Data from the National Health and Nutrition Examination Survey (NHANES) indicate 89% of Americans regularly consume caffeine, but these data do not include military personnel. This cross-sectional study examined caffeine use in Navy and Marine Corps personnel, including prevalence, amount of daily consumption, and factors associated with use. A random sample of Navy and Marine Corps personnel was contacted and asked to complete a detailed questionnaire describing their use of caffeine-containing substances, in addition to their demographic, military, and lifestyle characteristics. A total of 1708 service members (SMs) completed the questionnaire. Overall, 87% reported using caffeinated beverages ≥1 time/week, with caffeine users consuming a mean ± standard error of 226 ± 5 mg/day (242 ± 7 mg/day for men, 183 ± 8 mg/day for women). The most commonly consumed caffeinated beverages (% users) were coffee (65%), colas (54%), teas (40%), and energy drinks (28%). Multivariable logistic regression modeling indicated that characteristics independently associated with caffeine use (≥1 time/week) included older age, white race/ethnicity, higher alcohol consumption, and participating in less resistance training. Prevalence of caffeine use in these SMs was similar to that reported in civilian investigations, but daily consumption (mg/day) was higher.

Acute effects of coffee consumption on self-reported gastrointestinal symptoms, blood pressure and stress indices in healthy individuals

Background

It has been suggested that coffee may affect the gut-brain axis with conflicting outcomes. Moreover, there is insufficient evidence to determine whether the type or temperature of coffee consumed will have a different impact on the gut-brain axis. The purpose of this study was to investigate the effects of acute coffee consumption on the following: 1. self-reported GI symptoms and salivary gastrin, 2. stress indices [salivary cortisol and alpha-amylase (sAA)] and psychometric measures, and 3. blood pressure (BP), in healthy, daily coffee consuming individuals in non-stressful conditions.

Methods

This was a randomized, double blind, crossover clinical trial, in which 40 healthy individuals (20 men, 20 women), 20–55 years of age, randomly consumed four 200 ml coffee beverages containing 160 mg caffeine (hot and cold instant coffee, cold espresso, hot filtered coffee), 1 week apart. Salivary samples and psychometric questionnaires were collected at baseline and post-coffee consumption at 15,30, and 60 min for salivary gastrin and sAA measurements and at 60,120, and 180 min for cortisol measurements. BP was measured at beginning and end of each intervention. ClinicalTrials.gov ID: NCT02253628

Results

Coffee consumption significantly increased sAA activity (P = 0.041), with significant differences only between cold instant and filter coffee at 15 and 30 min post-consumption (P < 0.05). Coffee temporarily increased salivary gastrin, without differences between coffee types. Coffee did not affect salivary cortisol or self-reported anxiety levels. Coffee consumption significantly increased BP, within the healthy physiological levels, in a gender specific manner at the end of the experimental periods, without differences between coffee types.

Conclusion

Acute coffee consumption in non-stressful conditions activated sAA and BP but not salivary cortisol, indicating activation of the sympathetic nervous system. Post-coffee sAA increase without a concomitant cortisol increase may also indicate that coffee may have some anti-stress properties.

Association of coffee drinking with all-cause mortality: a systematic review and meta-analysis

OBJECTIVE

We aimed to use the meta-analysis method to assess the relationship between coffee drinking and all-cause mortality.

DESIGN

Categorical and dose-response meta-analyses were conducted using random-effects models.

SETTING

We systematically searched and identified eligible literature in the PubMed and Scopus databases.

SUBJECTS

Seventeen studies including 1 054 571 participants and 131 212 death events from all causes were included in the present study.

RESULTS

Seventeen studies were included and evaluated in the meta-analysis. A U-shaped dose-response relationship was found between coffee consumption and all-cause mortality (P for non-linearity <0.001). Compared with non/occasional coffee drinkers, the relative risks for all-cause mortality were 0.89 (95 % CI 0.85, 0.93) for 1-<3 cups/d, 0.87 (95 % CI 0.83, 0.91) for 3-<5 cups/d and 0.90 (95 % CI 0.87, 0.94) for ≥5 cups/d, and the relationship was more marked in females than in males.

CONCLUSIONS

The present meta-analysis of prospective cohort studies indicated that light to moderate coffee intake is associated with a reduced risk of death from all causes, particularly in women.

CYP1A2 and coffee intake and the modifying effect of sex, age, and smoking

BACKGROUND

The enzyme CYP1A2 (cytochrome 1A2) is involved in the metabolism of certain drugs and caffeine, and its activity can be influenced by factors such as sex, age, and smoking. The single nucleotide polymorphism (SNP) rs762551A>C, which has also been studied for its modifying effect on cardiovascular disease, has been reported to alter enzyme activity.

OBJECTIVE

The objective was to study the effect of CYP1A2, sex, age, and smoking on coffee intake.

DESIGN

Within the Rotterdam Study, a population-based cohort, all coffee drinkers for whom genome-wide association data were available were selected. Because SNP rs762551 was not on the Illumina 550 platform, SNP rs2472299 was used as a proxy, with the A allele of rs762551 linked to the G allele of rs2472299. Linear regression analyses were used to determine the effect and interaction of rs2472299, sex, age, and smoking on coffee intake. Adjusted geometric means of coffee intake were calculated per genotype for the different smoking and sex strata by using multivariable general linear models. A combined analysis, with the use of a "risk score," was performed to determine the contribution of each separate factor.

RESULTS

rs2472299G>A, female sex, and nonsmoking were significantly inversely related to coffee intake. Coffee intake was lowest in nonsmoking women homozygous for rs2472299G>A (3.49 cups/d; ∼436 mL). All factors contributed almost linearly to the intake of coffee, with the highest coffee intake in smoking men without the A allele (5.32 cups/d; ∼665 mL).

CONCLUSION

rs2472299G>A, linked to rs762551A>C, sex, age, and smoking significantly contribute to coffee intake.