Coffee consumption and risk of total and cardiovascular mortality among patients with type 2 diabetes

Dietary Factors and All-Cause Mortality in Individuals With Type 2 Diabetes: A Systematic Review and Meta-analysis of Prospective Observational Studies

BACKGROUND

Type 2 diabetes is a major health concern associated with mortality. Diet may influence the progression of diabetes; however, systematic reviews are lacking.

PURPOSE

This study systematically summarized the evidence on diet and all-cause mortality in individuals with type 2 diabetes.

DATA SOURCES

PubMed and Web of Science were searched until June 2022.

STUDY SELECTION

Prospective observational studies investigating dietary factors in association with all-cause mortality in individuals with type 2 diabetes were selected.

DATA SYNTHESIS

We identified 107 studies. Moderate certainty of evidence was found for inverse associations of higher intakes of fish (summary risk ratios per serving/week: 0.95; 95% CI 0.92, 0.99; n = 6 studies), whole grain (per 20 g/day: 0.84; 95% CI 0.71, 0.99; n = 2), fiber (per 5 g/day: 0.86; 95% CI 0.81, 0.91; n = 3), and n-3 polyunsaturated fatty acids (per 0.1 g/day: 0.87; 95% CI 0.82, 0.92; n = 2) and mortality. There was low certainty of evidence for inverse associations of vegetable consumption (per 100 g/day: 0.88; 95% CI 0.82, 0.94; n = 2), plant protein (per 10 g/day: 0.91; 95% CI 0.87, 0.96; n = 3), and for positive associations of egg consumption (per 10 g/day: 1.05; 95% CI 1.03, 1.08; n = 7) and cholesterol intake (per 300 mg/day: 1.19; 95% CI 1.13, 1.26; n = 2). For other dietary factors, evidence was uncertain or no association was observed.

CONCLUSIONS

Higher intake of fish, whole grain, fiber, and n-3 polyunsaturated fatty acids were inversely associated with all-cause mortality in individuals with type 2 diabetes. There is limited evidence for other dietary factors, and, thus, more research is needed.

Coffee consumption and cardiovascular diseases and mortality in patients with type 2 diabetes: A systematic review and dose-response meta-analysis of cohort studies

AIMS

To evaluate the long-term consequences of coffee drinking in patients with type 2 diabetes.

DATA SYNTHESIS

PubMed, Scopus, and Web of Sciences were searched to November 2020 for prospective cohort studies evaluating the association of coffee drinking with risk of cardiovascular disease (CVD) and mortality in patients with type 2 diabetes. Two reviewers extracted data and rated the certainty of evidence using GRADE approach. Random-effects models were used to estimate the hazard ratios (HRs) and 95% CIs. Dose-response associations were modeled by a one-stage mixed-effects meta-analysis. Ten prospective cohort studies with 82,270 cases were included. Compared to those with no coffee consumption, the HRs for consumption of 4 cups/d were 0.79 (95%CI: 0.72, 0.87; n = 10 studies) for all-cause mortality, 0.60 (95%CI: 0.46, 0.79; n = 4) for CVD mortality, 0.68 (95%CI: 0.51, 0.91; n = 3) for coronary heart disease (CHD) mortality, 0.72 (95%CI: 0.54, 0.98; n = 2) for CHD, and 0.77 (95%CI: 0.61, 0.98; n = 2) for total CVD events. There was no significant association for cancer mortality and stroke. There was an inverse monotonic association between coffee drinking and all-cause and CVD mortality, and inverse linear association for CHD and total CVD events. The certainty of evidence was graded moderate for all-cause mortality, and low or very low for other outcomes.

CONCLUSIONS

Drinking coffee may be inversely associated with the risk of mortality in patients with type 2 diabetes. However, more research is needed considering type of coffee, sugar and cream added to coffee, and history of CVD to present more confident results.

REGISTRY AND REGISTRY NUMBER

The protocol of this systematic review was registered at Open Science Framework (https://osf.io/8uaf3, registered form: osf.io/xur76, registration DOI: 10.17605/OSF.IO/8UAF3).

The Medicinal Chemistry of Caffeine

The purine alkaloid caffeine is the most widely consumed psychostimulant drug in the world and has multiple beneficial pharmacological activities, for example, in neurodegenerative diseases. However, despite being an extensively studied bioactive natural product, the mechanistic understanding of caffeine's pharmacological effects is incomplete. While several molecular targets of caffeine such as adenosine receptors and phosphodiesterases have been known for decades and inspired numerous medicinal chemistry programs, new protein interactions of the xanthine are continuously discovered providing potentially improved pharmacological understanding and a molecular basis for future medicinal chemistry. In this Perspective, we gather knowledge on the confirmed protein interactions, structure activity relationship, and chemical biology of caffeine on well-known and upcoming targets. The diversity of caffeine's molecular activities on receptors and enzymes, many of which are abundant in the CNS, indicates a complex interplay of several mechanisms contributing to neuroprotective effects and highlights new targets as attractive subjects for drug discovery.

Population segmentation of type 2 diabetes mellitus patients and its clinical applications - a scoping review

Background

Population segmentation permits the division of a heterogeneous population into relatively homogenous subgroups. This scoping review aims to summarize the clinical applications of data driven and expert driven population segmentation among Type 2 diabetes mellitus (T2DM) patients.

Methods

The literature search was conducted in Medline®, Embase®, Scopus® and PsycInfo®. Articles which utilized expert-based or data-driven population segmentation methodologies for evaluation of outcomes among T2DM patients were included. Population segmentation variables were grouped into five domains (socio-demographic, diabetes related, non-diabetes medical related, psychiatric / psychological and health system related variables). A framework for PopulAtion Segmentation Study design for T2DM patients (PASS-T2DM) was proposed.

Results

Of 155,124 articles screened, 148 articles were included. Expert driven population segmentation approach was most commonly used, of which judgemental splitting was the main strategy employed (n = 111, 75.0%). Cluster based analyses (n = 37, 25.0%) was the main data driven population segmentation strategies utilized. Socio-demographic (n = 66, 44.6%), diabetes related (n = 54, 36.5%) and non-diabetes medical related (n = 18, 12.2%) were the most used domains. Specifically, patients’ race, age, Hba1c related parameters and depression / anxiety related variables were most frequently used. Health grouping/profiling (n = 71, 48%), assessment of diabetes related complications (n = 57, 38.5%) and non-diabetes metabolic derangements (n = 42, 28.4%) were the most frequent population segmentation objectives of the studies.

Conclusions

Population segmentation has a wide range of clinical applications for evaluating clinical outcomes among T2DM patients. More studies are required to identify the optimal set of population segmentation framework for T2DM patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01209-w.

Additive effects of green tea and coffee on all-cause mortality in patients with type 2 diabetes mellitus: the Fukuoka Diabetes Registry

INTRODUCTION

The impact of consuming green tea or coffee on mortality in patients with diabetes is controversial. We prospectively investigated the impact of each beverage and their combination on mortality among Japanese patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In all, 4923 patients (2790 men, 2133 women) with type 2 diabetes (mean age, 66 years) were followed prospectively (median, 5.3 years; follow-up rate, 99.5%). We evaluated the amount of green tea and coffee consumed using self-administered questionnaires.

RESULTS

During the follow-up period, 309 participants died. The consumption of green tea, coffee, and a combination of the beverages was associated with reduced all-cause mortality. Multivariable-adjusted hazard ratios (95% CIs) for green tea were as follows: none 1.0 (referent); 0.85 (0.60-1.22) for ≤1 cup/day; 0.73 (0.51-1.03) for 2-3 cups/day; 0.60 (0.42-0.85) for ≥4 cups/day; and P for trend, 0.002. For coffee, they were: none 1.0 (referent); 0.88 (0.66-1.18) for <1 cup/day; 0.81 (0.58-1.13) for 1 cup/day; 0.59 (0.42-0.82) for ≥2 cups/day; P for trend, 0.002. With the combination they were 1.0 (referent) for no consumption of green tea and coffee; 0.49 (0.24-0.99) for 2-3 cups/day of green tea with ≥2 cups/day of coffee; 0.42 (0.20-0.88) for ≥4 cups/day of green tea with 1 cup/day of coffee; and 0.37 (0.18-0.77) for ≥4 cups/day of green tea with ≥2 cups/day of coffee.

CONCLUSIONS

Higher consumption of green tea and coffee was associated with reduced all-cause mortality: their combined effect appeared to be additive in patients with type 2 diabetes.

Coffee Consumption and Risk of Stroke: A Mendelian Randomization Study

OBJECTIVE

Observational epidemiological studies have reported a relationship between coffee intake and risk of stroke. However, evidence for this association is inconsistent, and it remains uncertain whether the association is causal or due to confounding or reverse causality. To clarify this relationship, we adopted a Mendelian randomization (MR) approach to evaluate the effects of coffee consumption on the risk of stroke and its subtypes.

METHODS

A meta-analysis of genome-wide association studies (GWASs) including 91,462 coffee consumers was used to identify instruments for coffee consumption. Summary-level data for stroke, intracerebral hemorrhage, ischemic stroke (IS), and IS subtypes were obtained from GWAS meta-analyses conducted by the MEGASTROKE consortium. MR analyses were performed using the inverse-variance-weighted, weighted-median, MR-PRESSO (Pleiotropy RESidual Sum and Outlier) test and MR-Egger regression. Sensitivity analyses were further performed using alternative instruments to test the robustness of our findings.

RESULTS

Genetically predicted coffee consumption (high vs infrequent/no) was not associated with risk of stroke. Similarly, among coffee consumers, MR analysis did not indicate causal associations between coffee consumption (cups/day) and risk of stroke. However, in the subgroup analysis, we found weak suggestive evidence for a potential protective effect of coffee consumption on risk of small vessel (SV)-IS, although the association did not reach statistical significance after correction for multiple comparisons.

INTERPRETATION

This study suggests that coffee consumption is not causally associated with risk of stroke or its subtypes. Further studies are warranted to elucidate the possible association between coffee intake and risk of SV-IS, as well as its potential underlying mechanisms. ANN NEUROL 2020;87:525-532.

Effects of Coffee Intake on Dyslipidemia Risk According to Genetic Variants in the ADORA Gene Family among Korean Adults

Current evidence on the effects of coffee intake on cardiovascular diseases is not consistent, in part contributed by the genetic variability of the study subjects. While adenosine receptors (ADORAs) are involved in caffeine signaling, it remains unknown how genetic variations at the ADORA loci correlate the coffee intake with cardiovascular diseases. The present study examined the associations of coffee intake with dyslipidemia risk depending on genetic variants in the ADORA gene family. The study involved a population-based cohort of 4898 Korean subjects. Consumption of more than or equal to a cup of coffee per day was associated with lower dyslipidemia risk in females carrying the ADORA2B minor allele rs2779212 (OR: 0.645, 95% CI: 0.506-0.823), but not in those with the major allele. At the ADORA2A locus, male subjects with the minor allele of rs5760423 showed instead an increased risk of dyslipidemia when consuming more than or equal to a cup of coffee per day (OR: 1.352, 95% CI: 1.014-1.802). The effect of coffee intake on dyslipidemia risk differs depending on genetic variants at the ADORA loci in a sex-specific manner. Our study suggests that a dietary guideline for coffee intake in the prevention and management of dyslipidemia ought to consider ADORA-related biomarkers carefully.

Potential nutraceutical and food additive properties and risks of coffee: a comprehensive overview

Coffee is a composite mixture of more than a thousand diverse phytochemicals like alkaloids, phenolic compounds, vitamins, carbohydrates, lipids, minerals and nitrogenous compounds. Coffee has multifunctional properties as a food additive and nutraceutical. As a nutraceutical, coffee has anti-inflammatory, anti-oxidant, antidyslipidemic, anti-obesity, type-2 diabetes mellitus (DM), and cardiovascular diseases (CVD), which can serve for the treatment and prevention of metabolic syndrome and associated disorders. On the other hand, as a food additive, coffee has antimicrobial activity against a wide range of microorganisms, inhibits lipid peroxidation (LPO), and can function as a prebiotic. The outcomes of different studies also revealed that coffee intake may reduce the incidence of numerous chronic diseases, like liver disease, mental health, and it also overcomes the all-cause mortality, and suicidal risks. In some studies, high intake of coffee is linked to increase CVD risk factors, like cholesterol, plasma homocysteine and blood pressure (BP). There is also a little evidence that associated the coffee consumption with increased risk of lung tumors in smokers. Among adults who consume the moderate amount of coffee, there is slight indication of health hazards with strong indicators of health benefits. Moreover, existing literature suggests that it may be cautious for pregnant women to eliminate the chances of miscarriages and impaired fetal growth. The primary purpose of this narrative review is to provide an overview of the findings of the positive impacts and risks of coffee consumption on human health. In conclusion, to date, the best available evidence from research indicates that drinking coffee up to 3-4 cups/day provides health benefits for most people.

Pharmacological potential of methylxanthines: Retrospective analysis and future expectations

Methylated xanthines (methylxanthines) are available from a significant number of different botanical species. They are ordinarily included in daily diet, in many extremely common beverages and foods. Caffeine, theophylline and theobromine are the main methylxanthines available from natural sources. The supposedly relatively low toxicity of methylxanthines, combined with the many beneficial effects that have been attributed to these compounds through time, generated a justified attention and a very prolific ground for dedicated scientific reports. Methylxanthines have been widely used as therapeutical tools, in an intriguing range of medicinal scopes. In fact, methylxanthines have been/were medically used as Central Nervous System stimulants, bronchodilators, coronary dilators, diuretics and anti-cancer adjuvant treatments. Other than these applications, methylxanthines have also been hinted to hold other beneficial health effects, namely regarding neurodegenerative diseases, cardioprotection, diabetes and fertility. However, it seems now consensual that toxicity concerns related to methylxanthine consumption and/or therapeutic use should not be dismissed. Taking all the knowledge and expectations on the potential of methylxanthines into account, we propose a systematic look at the past and future of methylxanthine pharmacologic applications, discussing all the promise and anticipating possible constraints. Anyways, methylxanthines will still substantiate considerable meaningful research and discussion for years to come.

Caffeine Consumption and Mortality in Diabetes: An Analysis of NHANES 1999-2010

Aim: An inverse relationship between coffee consumption and mortality has been reported in the general population. However, the effect of coffee consumption in diabetes remains unclear. We aimed to evaluate the association of caffeine consumption and caffeine source with mortality among patients with diabetes. Methods: We examined the association of caffeine consumption with mortality among 1974 women and 1974 men with diabetes, using the National Health and Nutrition Examination Survey (NHANES) 1999-2010. Caffeine consumption was assessed at baseline using 24 h dietary recalls. Cox proportional hazard models were fitted to estimate hazard ratios (HR) for all-cause, cardiovascular, and cancer-related mortality according to caffeine consumption and its source, adjusting for potential confounders. Results: A dose-dependent inverse association between caffeine and all-cause mortality was observed in women with diabetes. Adjusted HR for death among women who consumed caffeine, as compared with non-consumers, were: 0.57 (95% CI, 0.40-0.82) for <100 mg of caffeine/day, 0.50 (95% CI, 0.32-0.78) for 100 to <200 mg of caffeine/day, and 0.39 (95% CI, 0.23-0.64) for ≥200 mg of caffeine/day (p = 0.005 for trend). This association was not observed in men. There was a significant interaction between sex and caffeine consumption (p = 0.015). No significant association between total caffeine consumption and cardiovascular or cancer mortality was observed. Women who consumed more caffeine from coffee had reduced risk of all-cause mortality (p = 0.004 for trend). Conclusion: Our study showed a dose-dependent protective effect of caffeine consumption on mortality among women with diabetes.

Structure-Bioactivity Relationships of Methylxanthines: Trying to Make Sense of All the Promises and the Drawbacks

Methylxanthines are a group of phytochemicals derived from the purine base xanthine and obtained from plant secondary metabolism. They are unobtrusively included in daily diet in common products as coffee, tea, energetic drinks, or chocolate. Caffeine is by far the most studied methylxanthine either in animal or epidemiologic studies. Theophylline and theobromine are other relevant methylxanthines also commonly available in the aforementioned sources. There are many disseminated myths about methylxanthines but there is increased scientific knowledge to discuss all the controversy and promise shown by these intriguing phytochemicals. In fact, many beneficial physiologic outcomes have been suggested for methylxanthines in areas as important and diverse as neurodegenerative and respiratory diseases, diabetes or cancer. However, there have always been toxicity concerns with methylxanthine (over)consumption and pharmacologic applications. Herein, we explore the structure-bioactivity relationships to bring light those enumerated effects. The potential shown by methylxanthines in such a wide range of conditions should substantiate many other scientific endeavors that may highlight their adequacy as adjuvant therapy agents and may contribute to the advent of functional foods. Newly designed targeted molecules based on methylxanthine structure may originate more specific and effective outcomes.

2-Furoylglycine as a Candidate Biomarker of Coffee Consumption

Specific and sensitive food biomarkers are necessary to support dietary intake assessment and link nutritional habits to potential impact on human health. A multistep nutritional intervention study was conducted to suggest novel biomarkers for coffee consumption. (1)H NMR metabolic profiling combined with multivariate data analysis resolved 2-furoylglycine (2-FG) as a novel putative biomarker for coffee consumption. We relatively quantified 2-FG in the urine of coffee drinkers and investigated its origin, metabolism, and excretion kinetics. When searching for its potential precursors, we found different furan derivatives in coffee products, which are known to get metabolized to 2-FG. Maximal urinary excretion of 2-FG occurred 2 h after consumption (p = 0.0002) and returned to baseline after 24 h (p = 0.74). The biomarker was not excreted after consumption of coffee substitutes such as tea and chicory coffee and might therefore be a promising acute biomarker for the detection of coffee consumption in human urine.

Tea consumption and mortality of all cancers, CVD and all causes: a meta-analysis of eighteen prospective cohort studies

Epidemiological studies have demonstrated inconsistent associations between tea consumption and mortality of all cancers, CVD and all causes. To obtain quantitative overall estimates, we conducted a dose-response meta-analysis of prospective cohort studies. A literature search in PubMed and Embase up to April 2015 was conducted for all relevant papers published. Random-effects models were used to calculate pooled relative risks (RR) with 95 % CI. In eighteen prospective studies, there were 12 221, 11 306 and 55 528 deaths from all cancers, CVD and all causes, respectively. For all cancer mortality, the summary RR for the highest v. lowest category of green tea and black tea consumption were 1·06 (95 % CI 0·98, 1·15) and 0·79 (95 % CI 0·65, 0·97), respectively. For CVD mortality, the summary RR for the highest v. lowest category of green tea and black tea consumption were 0·67 (95 % CI 0·46, 0·96) and 0·88 (95 % CI 0·77, 1·01), respectively. For all-cause mortality, the summary RR for the highest v. lowest category of green tea and black tea consumption were 0·80 (95 % CI 0·68, 0·93) and 0·90 (95 % CI 0·83, 0·98), respectively. The dose-response analysis indicated that one cup per d increment of green tea consumption was associated with 5 % lower risk of CVD mortality and with 4 % lower risk of all-cause mortality. Green tea consumption was significantly inversely associated with CVD and all-cause mortality, whereas black tea consumption was significantly inversely associated with all cancer and all-cause mortality.

The coffee paradox in stroke: Increased consumption linked with fewer strokes

OBJECTIVE

To determine the association in amount of daily coffee consumption with incidence of stroke in a broad cohort, considering other vascular risk factors.

METHODS

We utilized the Third National Health and Nutrition Examination Survey (1988-1994; NHANES III) data on participants aged ≥17 years old to examine coffee consumption and stroke. Multivariate logistic regression models related the amount of coffee use reported in a food frequency questionnaire with stroke, controlling for other vascular risk factors.

RESULTS

Of 33 994 NHANES III subjects, coffee consumption and stroke data in adults ≥17 years old were available in 19 994. Daily coffee consumption ranged from 0 to 20 (median 1) cups and 644 (3.2%) participants had a stroke diagnosed by a physician. Coffee intake varied with age, gender, and ethnicity (P < 0.001). Interestingly, heart failure, diabetes, and hypertension were less frequent, and high cholesterol more frequent in those consuming ≥3 cups per day (P < 0.001). Smoking was more frequent in all coffee drinkers (P < 0.0001). Multivariate analyses revealed an independent effect of heavier coffee consumption (≥3 cups/day) on reduced stroke (OR 0.44, 95% CI 0.22-0.87, P < 0.02) in healthy subjects that was attenuated by vascular risk factors (OR 0.78, 95% CI 0.58-1.07, P ≈ 0.12).

CONCLUSION

Heavier daily coffee consumption is associated with decreased stroke prevalence, despite smoking tendency in heavy coffee drinkers.

Association of coffee intake with total and cause-specific mortality in a Japanese population: the Japan Public Health Center-based Prospective Study

BACKGROUND

Despite the rising consumption of coffee worldwide, few prospective cohort studies assessed the association of coffee intake with mortality including total and major causes of death.

OBJECTIVE

We aimed to investigate the association between habitual coffee drinking and mortality from all causes, cancer, heart disease, cerebrovascular disease, respiratory disease, injuries, and other causes of death in a large-scale, population-based cohort study in Japan.

DESIGN

We studied 90,914 Japanese persons aged between 40 and 69 y without a history of cancer, cerebrovascular disease, or ischemic heart disease at the time of the baseline study. Subjects were followed up for an average of 18.7 y, during which 12,874 total deaths were reported. The association between coffee intake and risk of total and cause-specific mortality was assessed by using a Cox proportional hazards regression model with adjustment for potential confounders.

RESULTS

We showed an inverse association between coffee intake and total mortality in both men and women. HRs (95% CIs) for total death in subjects who consumed coffee compared with those who never drank coffee were 0.91 (0.86-0.95) for <1 cup/d, 0.85 (0.81-0.90) for 1-2 cups/d, 0.76 (0.70-0.83) for 3-4 cups/d, and 0.85 (0.75-0.98) for >5 cups/d (P-trend < 0.001). Coffee was inversely associated with mortality from heart disease, cerebrovascular disease, and respiratory disease.

CONCLUSION

With this prospective study, we suggest that the habitual intake of coffee is associated with lower risk of total mortality and 3 leading causes of death in Japan.

Effect of chronic coffee consumption on weight gain and glycaemia in a mouse model of obesity and type 2 diabetes

Objective:

Epidemiological evidence shows that chronic coffee consumption in humans is correlated with a lower incidence of type 2 diabetes mellitus. For the experimental exploration of the underlying mechanisms, this effect needs to be replicated in an animal model of type 2 diabetes with a short lifespan.

Design:

Male C57BL/6 mice consumed regular coffee or water ad libitum and the development of obesity and diabetes caused by high-fat diet (55% lipids, HFD) was observed from week 10 on for 35 weeks in comparison with mice feeding on a defined normal diet (9% lipids, ND).

Results:

The massive weight gain in HFD mice was dose-dependently retarded (P=0.034), the moderate weight gain in ND mice was abolished (P<0.001) by coffee consumption, probably because of a lower feeding efficiency. The consumption of fluid (water or coffee) was significantly diminished by HFD (P<0.001), resulting in a higher coffee exposure of ND mice. On week 21 intraperitoneal glucose tolerance tests (IPGTT) showed a dose-dependent faster decline of elevated glucose levels in coffee-consuming HFD mice (P=0.016), but not in ND mice. Remarkably, a spontaneous decrease in non-fasting glycaemia occurred after week 21 in all treatment groups (P<0.001). On week 39 the IPGTT showed diminished peak of glucose levels in coffee-consuming HFD mice (P<0.05). HFD mice were hyperinsulinaemic and had significantly (P<0.001) enlarged islets. Coffee consumption did not affect islet size or parameters of beta-cell apoptosis, proliferation and insulin granule content.

Conclusion:

Coffee consumption retarded weight gain and improved glucose tolerance in a mouse model of type 2 diabetes and corresponding controls. This gives rise to the expectation that further insight into the mechanism of the diabetes-preventive effect of coffee consumption in humans may be gained by this approach.

Current evidence for the use of coffee and caffeine to prevent age-related cognitive decline and Alzheimer's disease

Although nothing has been proven conclusively to protect against cognitive aging, Alzheimer's disease or related dementias, decades of research suggest that specific approaches including the consumption of coffee may be effective. While coffee and caffeine are known to enhance short-term memory and cognition, some limited research also suggests that long-term use may protect against cognitive decline or dementia. In vitro and pre-clinical animal models have identified plausible neuroprotective mechanisms of action of both caffeine and other bioactive components of coffee, though epidemiology has produced mixed results. Some studies suggest a protective association while others report no benefit. To our knowledge, no evidence has been gathered from randomized controlled trials. Although moderate consumption of caffeinated coffee is generally safe for healthy people, it may not be for everyone, since comorbidities and personal genetics influence potential benefits and risks. Future studies could include short-term clinical trials with biomarker outcomes to validate findings from pre-clinical models and improved epidemiological studies that incorporate more standardized methods of data collection and analysis. Given the enormous economic and emotional toll threatened by the current epidemic of Alzheimer's disease and other dementias, it is critically important to validate potential prevention strategies such as coffee and caffeine.

Long-term coffee consumption and risk of cardiovascular disease: a systematic review and a dose-response meta-analysis of prospective cohort studies

BACKGROUND

Considerable controversy exists on the association between coffee consumption and cardiovascular disease (CVD) risk. A meta-analysis was performed to assess the dose-response relationship of long-term coffee consumption with CVD risk.

METHODS AND RESULTS

PubMed and EMBASE were searched for prospective cohort studies of the relationship between coffee consumption and CVD risk, which included coronary heart disease, stroke, heart failure, and CVD mortality. Thirty-six studies were included with 1 279 804 participants and 36 352 CVD cases. A nonlinear relationship of coffee consumption with CVD risk was identified (P for heterogeneity=0.09, P for trend <0.001, P for nonlinearity <0.001). Compared with the lowest category of coffee consumption (median, 0 cups per day), the relative risk of CVD was 0.95 (95% confidence interval, 0.87-1.03) for the highest category (median, 5 cups per day) category, 0.85 (95% confidence interval, 0.80-0.90) for the second highest category (median, 3.5 cups per day), and 0.89 (95% confidence interval, 0.84-0.94) for the third highest category (median, 1.5 cups per day). Looking at separate outcomes, coffee consumption was nonlinearly associated with both coronary heart disease (P for heterogeneity=0.001, P for trend <0.001, P for nonlinearity <0.001) and stroke (P for heterogeneity=0.07, P for trend <0.001, P for nonlinearity <0.001; P for trend differences >0.05) risks.

CONCLUSIONS

A nonlinear association between coffee consumption and CVD risk was observed in this meta-analysis. Moderate coffee consumption was inversely significantly associated with CVD risk, with the lowest CVD risk at 3 to 5 cups per day, and heavy coffee consumption was not associated with elevated CVD risk.

Coffee and tea consumption are inversely associated with mortality in a multiethnic urban population

Coffee and tea are commonly consumed beverages. Inverse associations with mortality have been suggested for coffee and tea, but the relationships with cause-specific mortality are not well understood. We examined regular and decaffeinated coffee and tea in relation to mortality due to all causes, vascular, nonvascular, and cancer in the multi-ethnic, prospective, population-based Northern Manhattan Study. The study population included 2461 participants with diet data who were free of stroke, myocardial infarction, and cancer at baseline (mean age 68.30 ± 10.23 y, 36% men, 19% white, 23% black, 56% Hispanic). During a mean follow-up of 11 y, we examined the associations between coffee and tea consumption, assessed by food frequency questionnaire, and 863 deaths (342 vascular related and 444 nonvascular including 160 cancer deaths) using multivariable-adjusted Cox models. Coffee consumption was inversely associated with all-cause mortality [for each additional cup/d, HR = 0.93 (95% CI: 0.88, 0.99); P = 0.02]. Caffeinated coffee was inversely associated with all-cause mortality, driven by a strong protection among those who drank ≥4 cups/d. An inverse dose-response relationship between tea and all-cause mortality was suggested [for each additional cup/d, HR = 0.91 (95% CI: 0.84, 0.99); P = 0.01]. Coffee consumption ≥4/d was protective against nonvascular death [vs. <1/mo, HR = 0.57 (95% CI: 0.33, 0.97)] and tea consumption ≥2/d was protective against nonvascular death [HR = 0.63 (95% CI: 0.41, 0.95)] and cancer [HR = 0.33 (95% CI: 0.14, 0.80)]. There was a strong inverse association between coffee and vascular-related mortality among Hispanics only. Further study is needed, including investigation into the mechanisms and compounds in coffee and tea responsible for the inverse associations with mortality. The differential relationship between coffee and vascular death across race/ethnicity underscores the need for research in similar multi-ethnic cohorts including Hispanics.

Effects of habitual coffee consumption on cardiometabolic disease, cardiovascular health, and all-cause mortality

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.

Dose- and gender-dependent interactions between coffee consumption and serum GGT activity in alcohol consumers

AIMS

Coffee consumption has been recently linked with decreased blood gamma-glutamyltransferase (GGT) activities and protection from alcoholic liver disease. To explore the relationship and dose response, we assessed the impacts of coffee and alcohol intake on serum GGT activity in apparently healthy men and women with varying levels of coffee and alcohol consumption.

METHODS

Data on coffee, alcohol consumption and serum GGT activities were collected from 18,899 individuals (8807 men and 10,092 women), mean age 48 years, range 25-74 years, who participated in a large national cross-sectional health survey. Body mass index, smoking index and age were used as covariates in all analyses.

RESULTS

Among the study population, 89.8% reported varying levels of coffee consumption; 6.9% were abstainers from alcohol, 86.1% moderate drinkers, 3.7% heavy drinkers and 3.3% former drinkers. In men, the elevation of GGT induced by heavy drinking (>280 g/week) was found to be significantly reduced by coffee consumption exceeding 4 cups per day. A similar trend was also observed among women, which however, did not reach statistical significance.

CONCLUSION

Coffee modulates the effect of ethanol on serum GGT activities in a dose- and gender-dependent manner. These observations should be implicated in studies on the possible hepatoprotective effects of coffee in alcohol consumers.

Tea consumption and risk of stroke: a dose-response meta-analysis of prospective studies

OBJECTIVE

To determine the association between tea consumption and the risk of stroke.

METHODS

We searched the PubMed database from January 1966 to March 2012 and reviewed reference lists of retrieved articles to identify relevant studies. Studies were included if they reported relative risks (RRs) and corresponding 95% confidence intervals (CIs) of stroke with respect to three or more categories of tea consumption. A random-effects model was used to combine the study-specific risk estimates.

RESULTS

Fourteen studies, consisting of 513,804 participants with a median follow-up of 11.5 years, were included in this meta-analysis. We observed a modest but statistically significant inverse association between tea consumption and risk of stroke. An increase of three cups/d in tea consumption was associated with a 13% decreased risk of stroke (RR 0.87; 95% CI, 0.81-0.94). The decreased risk of stroke with tea consumption was consistent among most subgroups. Based on the three studies that provided results for stroke subtypes, tea consumption was also inversely associated with the risk of ischemic stroke (RR 0.76; 95% CI, 0.69-0.84), but not cerebral hemorrhage (RR 0.96; 95% CI, 0.82-1.11) or subarachnoid hemorrhage (RR 0.81; 95% CI, 0.57-1.16).

CONCLUSIONS

Tea consumption is associated with a decreased risk of stroke, particularly ischemic stroke. More well-designed, rigorously conducted studies are needed in order to make confident conclusions about the association between tea consumption and stroke subtypes.

Effects of tea and coffee on cardiovascular disease risk

Tea and coffee have been associated with risk of cardiovascular disease (CVD), both positively and negatively. Epidemiological data suggest that black and green tea may reduce the risk of both coronary heart disease and stroke by between 10 and 20%. Experimental and clinical trial data generally indicate either neutral or beneficial effects on risk factors and pathways linked to the development of CVD. Controversy still exists regarding the effects of coffee, where there have been concerns regarding associations with hypercholesterolaemia, hypertension and myocardial infarction. However, long term moderate intake of coffee is not associated with detrimental effects in healthy individuals and may even protect against the risk of developing type 2 diabetes. The detrimental effects of coffee may be associated with the acute pressor effects, most likely due to caffeine at high daily intakes, and lipids from boiled coffee can contribute to raised serum cholesterol. Genetic polymorphisms in enzymes involved in uptake, metabolism and excretion of tea and coffee compounds are also associated with differential biological effects. Potential mechanisms by which tea and coffee phytochemicals can exert effects for CVD protection include the regulation of vascular tone through effects on endothelial function, improved glucose metabolism, increased reverse cholesterol transport and inhibition of foam cell formation, inhibition of oxidative stress, immunomodulation and effects on platelet function (adhesion and activation, aggregation and clotting). The phytochemical compounds in tea and coffee and their metabolites are suggested to influence protective endogenous pathways by modulation of gene-expression. It is not known exactly which compounds are responsible for the suggestive protective effects of tea and coffee. Although many biologically active compounds have been identified with known biological effects, tea and coffee contain many unidentified compounds with potential bioactivity.

How can diet influence the risk of stroke?

Cerebrovascular diseases are the second cause of mortality in the world, and hypertension is considered a main risk factor for occurrence of stroke. The mechanisms responsible for the increased stroke risk remain unclear. However, dietary interventions have been applied in the management and treatment of their risk factors, which include increased blood pressure levels, obesity, diabetes, and dyslipidemia. Further studies should be conducted to assess the effects of carotenoids, flavonoids, n-3 polyunsaturated fats, and lower salt and high glycemic index intake in risk of stroke.

Role of coffee in modulation of diabetes risk

Coffee consumption has been associated with a lower risk of type 2 diabetes. This association does not depend on race, gender, geographic distribution of the study populations, or the type of coffee consumed (i.e., caffeinated or decaffeinated). This review discusses the strength of this relationship, examines the possibility that the pattern of coffee consumption could influence the association, and evaluates the possible relationship between coffee consumption and other risk factors associated with diabetes. Particular attention is paid to the identification, on the basis of the scientific evidence, of the possible mechanisms by which coffee components might affect diabetes development, especially in light of the paradoxical effect of caffeine on glucose metabolism. In addition to the role of coffee in reducing the risk of developing type 2 diabetes, the possible role of coffee in the course of the illness is explored. Finally, the possibility that coffee can also affect the risk of other forms of diabetes (e.g., type 1 diabetes and gestational diabetes) is examined.

Functional foods and nutraceuticals in the primary prevention of cardiovascular diseases

Cardiovascular disease (CVD) is now the leading cause of death globally and is a growing health concern. Dietary factors are important in the pathogenesis of CVD and may to a large degree determine CVD risk, but have been less extensively investigated. Functional foods are those that are thought to have physiological benefits and/or reduce the risk of chronic disease beyond their basic nutritional functions. The food industry has started to market products labelled as “functional foods.” Although many review articles have focused on individual dietary variables as determinants of CVD that can be modified to reduce the risk of CVD, the aim of this current paper was to examine the impact of functional foods in relation to the development and progression of CVD. Epidemiologic studies have demonstrated the association between certain dietary patterns and cardiovascular health. Research into the cardio-protective potential of their dietary components might support the development of functional foods and nutraceuticals. This paper will also compare the effect of individual bioactive dietary compounds with the effect of some dietary patterns in terms of their cardiovascular protection.

Coffee consumption and risk of stroke: a dose-response meta-analysis of prospective studies

Coffee consumption has been inconsistently associated with risk of stroke. The authors conducted a meta-analysis of prospective studies to quantitatively assess the association between coffee consumption and stroke risk. Pertinent studies were identified by searching PubMed and Embase from January 1966 through May 2011 and by reviewing the reference lists of retrieved articles. Prospective studies in which investigators reported relative risks of stroke for 3 or more categories of coffee consumption were eligible. Results from individual studies were pooled using a random-effects model. Eleven prospective studies, with 10,003 cases of stroke and 479,689 participants, met the inclusion criteria. There was some evidence of a nonlinear association between coffee consumption and risk of stroke (P for nonlinearity = 0.005). Compared with no coffee consumption, the relative risks of stroke were 0.86 (95% confidence interval (95% CI): 0.78, 0.94) for 2 cups of coffee per day, 0.83 (95% CI: 0.74, 0.92) for 3-4 cups/day, 0.87 (95% CI: 0.77, 0.97) for 6 cups/day, and 0.93 (95% CI: 0.79, 1.08) for 8 cups/day. There was marginal between-study heterogeneity among study-specific trends (I₂ = 12% and I₂ = 20% for the first and second spline transformations, respectively). Findings from this meta-analysis indicate that moderate coffee consumption may be weakly inversely associated with risk of stroke.

The effect of coffee on blood pressure and cardiovascular disease in hypertensive individuals: a systematic review and meta-analysis

BACKGROUND

The effect of coffee and caffeine on blood pressure (BP) and cardiovascular disease (CVD) in hypertensive persons is uncertain.

OBJECTIVE

The objective was to summarize the evidence on the acute and longer-term effects of caffeine and coffee intake on BP and on the association between habitual coffee consumption and risk of CVD in hypertensive individuals.

DESIGN

A systematic review and meta-analysis of publications identified in a PubMed and EMBASE search up to 30 April 2011 was undertaken. Data were extracted from controlled trials on the effect of caffeine or coffee intake on BP change and from cohort studies on the association between habitual coffee consumption and CVD.

RESULTS

In 5 trials, the administration of 200-300 mg caffeine produced a mean increase of 8.1 mm Hg (95% CI: 5.7, 10.6 mm Hg) in systolic BP and of 5.7 mm Hg (95% CI: 4.1, 7.4 mm Hg) in diastolic BP. The increase in BP was observed in the first hour after caffeine intake and lasted ≥3 h. In 3 studies of the longer-term effect (2 wk) of coffee, no increase in BP was observed after coffee was compared with a caffeine-free diet or was compared with decaffeinated coffee. Last, 7 cohort studies found no evidence of an association between habitual coffee consumption and a higher risk of CVD.

CONCLUSIONS

In hypertensive individuals, caffeine intake produces an acute increase in BP for ≥3 h. However, current evidence does not support an association between longer-term coffee consumption and increased BP or between habitual coffee consumption and an increased risk of CVD in hypertensive subjects.

Coffee and its consumption: benefits and risks

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.

Coffee consumption and risk of stroke in women

BACKGROUND AND PURPOSE

Coffee consumption has been inconsistently associated with stroke incidence and mortality in previous studies. We investigated the association between coffee consumption and stroke incidence in the Swedish Mammography Cohort.

METHODS

We prospectively followed of 34,670 women without a history of cardiovascular disease or cancer at baseline in 1997. Coffee consumption was assessed in 1997 using a self-administered questionnaire. Incident stroke cases were ascertained from the Swedish Hospital Discharge Registry.

RESULTS

During a mean follow-up of 10.4 years, we ascertained 1680 stroke events, including 1310 cerebral infarctions, 154 intracerebral hemorrhages, 79 subarachnoid hemorrhages, and 137 unspecified strokes. After adjustment for other risk factors, coffee consumption was associated with a statistically significant lower risk of total stroke, cerebral infarction, and subarachnoid hemorrhage but not intracerebral hemorrhage. The multivariable relative risks of total stroke across categories of coffee consumption (<1 cup/day, 1 to 2 cups/day, 3 to 4 cups/day, and ≥5 cups/day) were 1.00, 0.78 (95% CI, 0.66 to 0.91), 0.75 (95% CI, 0.64 to 0.88), and 0.77 (95% CI, 0.63 to 0.92, respectively; P for trend=0.02). The association between coffee consumption and cerebral infarction was not modified by smoking status, body mass index, history of diabetes or hypertension, or alcohol consumption.

CONCLUSIONS

These findings suggest that low or no coffee consumption is associated with an increased risk of stroke in women.

Methylxanthines and human health: epidemiological and experimental evidence

When considering methylxanthines and human health, it must be recognized that in many countries most caffeine is consumed as coffee. This is further confounded by the fact that coffee contains many bioactive substances in addition to caffeine; it is rich in phenols (quinides, chlorogenic acid, and lactones) and also has diterpenes (fatty acid esters), potassium, niacin, magnesium, and the vitamin B(3) precursor trigonelline. There is a paradox as consumption of either caffeine or caffeinated coffee results in a marked insulin resistance and yet habitual coffee consumption has repeatedly been reported to markedly reduce the risk for type 2 diabetes. There is strong evidence that caffeine reduces insulin sensitivity in skeletal muscle and this may be due to a combination of direct antagonism of A(1) receptors and indirectly β-adrenergic stimulation as a result of increased sympathetic activity. Caffeine may also induce reduced hepatic glucose output. With the exception of bone mineral, there is little evidence that caffeine impacts negatively on other health issues. Coffee does not increase the risk of cardiovascular diseases or cancers and there is some evidence suggesting a positive relationship for the former and for some cancers, particularly hepatic cancer.

Consumption of filtered and boiled coffee and the risk of first acute myocardial infarction; a nested case/referent study

BACKGROUND AND AIM

In northern Sweden, consumption of both filtered and boiled coffee is common. Boiled coffee, especially popular in rural areas, is known to raise blood lipids, a risk factor for acute myocardial infarction (MI). To our knowledge, only one epidemiological study, a case-control study from Sweden, has investigated boiled coffee in MI, noting an increased risk at high consumption levels in men, and no association in women. The aim of the present nested case-referent study was to relate consumption of filtered and boiled coffee to the risk of first MI.

METHODS AND RESULTS

The study subjects were 375 cases (303 men, 72 women) and 1293 matched referents from the population-based Northern Sweden Health and Disease Study. Coffee consumption was assessed by food frequency questionnaire. Risk estimates were calculated by conditional logistic regression. A statistically significant positive association was found between consumption of filtered coffee and MI risk in men [odds ratio for consumption > or = 4 times/day versus < or = 1 time/day 1.73 (95% CI 1.05-2.84)]. In women, a similar association was observed, but for boiled coffee [odds ratio 2.51 (95% CI 1.08-5.86)]. After adjustment for current smoking, postsecondary education, hypertension, and sedentary lifestyle, the results for women were no longer statistically significant.

CONCLUSION

Consumption of filtered coffee was positively associated with the risk of a first MI in men. A similar tendency was observed for boiled coffee in women, but the result was not statistically significant in multivariate analysis. Further investigation in a larger study is warranted.