Green Tea and Coffee Consumption and All-Cause Mortality Among Persons With and Without Stroke or Myocardial Infarction

Unraveling tea and coffee consumption effects on cardiovascular diseases risk factors: A narrative review

Backgrounds and Aims

Daily lifestyle plays a vital role in modifying the risk for cardiovascular diseases (CVDs). Our daily life isn't inseparable from nutrition intake. As such, tea and coffee are often regarded as the most consumed beverages worldwide. There have been a lot of debates on the adverse effects and benefits of consuming these popular beverages. This comprehensive review explores the different types of tea and coffee and their mechanism of action. It delves deeper into their roles in reducing CVD risk, aiding CVD recovery, lowering CVD mortality, and their varying effects across populations and regions.

Methods

An extensive literature search was conducted on PubMed. Relevant articles were identified through cross-referencing and manual searches. Excluded from the study were commentaries, case reports, clinical vignettes, and non-English articles.

Results

Tea and coffee contain varying levels of caffeine and other bioactive compounds with cardioprotective effects against oxidative stress, inflammation, and more. Genetic factors further modulate their effects. Tea flavonoids benefit cholesterol, blood pressure, and endothelial function, while coffee constituents impact oxidative stress, metabolism, insulin sensitivity, and gut flora. Moderate consumption of both beverages may offer cardiovascular benefits, but outcomes vary depending on populations and conditions. Tea and coffee consumption may influence CVD recovery by reducing mortality and improving survival, however, it must be noted that it has the potential to be harmful to some individuals.

Conclusion

Evidence suggests that moderate consumption of these beverages may be linked to reduced cardiovascular mortality, although individual characteristics and pre-existing conditions can influence outcomes. Excessive caffeine consumption, found in both beverages, may pose risks such as arrhythmias, hypertension, and cardiovascular mortality in CVD patients, with a dose-dependent nature. Future research should delve into mechanisms, genetic factors, and diverse cultural impacts of its use. Health care providers should consider individual characteristics when advising on tea and coffee consumption in the context of cardiovascular health.

Impact of Green Tea Consumption on the Prevalence of Cardiovascular Outcomes: A Systematic Review

Cardiovascular diseases (CVDs) represent a major global health concern, responsible for significant morbidity, mortality, and disability. To mitigate the impact of CVDs, individuals often seek preventive measures, and one such approach is the consumption of green tea. This study aims to provide a comprehensive and up-to-date assessment of the effects of green tea consumption on the prevalence of cardiovascular outcomes. Following PRISMA guidelines, we conducted a systematic review using PubMed and Google Scholar databases to identify relevant studies. Our analysis revealed that the risk factors associated with CVDs can vary across different diseases, with hypertension being a common risk factor for CVD mortality and CVD. Notably, the consumption of green tea exhibited a positive effect on reducing the prevalence of cardiometabolic risks and hypercholesterolemia. Furthermore, green tea consumption was observed to have a beneficial impact on lowering both diastolic and systolic blood pressure. In conclusion, the studies reviewed in this research suggest that the consumption of green tea has a significant and positive influence on cardiovascular health. These findings highlight the potential of green tea as a valuable component of a healthy lifestyle, offering a promising avenue for its use as a dietary supplement to reduce the risk of CVDs.

Television Viewing Time and All-cause and Cardiovascular Disease Mortality Among Japanese Adults with and without a History of Stroke or Myocardial Infarction

AIMS

We examined the association between television (TV) viewing time and all-cause and cardiovascular disease (CVD) mortality among Japanese adults with and without a history of stroke or myocardial infarction (MI).

METHODS

In the Japan Collaborative Cohort Study, 76,572 participants (851 stroke survivors, 1,883 MI survivors, and 73,838 persons without a history of stroke or MI), aged 40-79 years at baseline (1988-1990), completed a lifestyle, diet, and medical history questionnaire, and were followed up regarding mortality until 2009. The Cox proportional hazard model was used to calculate the multivariable-adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) of all-cause and CVD mortality.

RESULTS

During the 19.3-year median follow-up period, 17,387 deaths were documented. TV viewing time was positively associated with all-cause and CVD mortality regardless of stroke or MI history. The multivariable-adjusted HRs of all-cause mortality with 95% CIs for TV viewing time of 3-4.9 h, 5-6.9 h, and ≥ 7 h were 1.18 (0.95-1.48), 1.12 (0.86-1.45), and 1.61 (1.12-2.32) for stroke survivors; 0.97 (0.81-1.17), 1.40 (1.12-1.76), and 1.44 (1.02-2.03) for MI survivors; and 1.00 (0.96-1.03), 1.07 (1.01-1.12), and 1.22 (1.11-1.34) for persons without a history of stroke or MI, respectively, compared with ＜3 h.

CONCLUSIONS

Prolonged TV viewing time was associated with higher risks of all-cause and CVD mortality in stroke or MI survivors and in persons without a history of them. It may be recommended to reduce sedentary time for stroke or MI survivors, independent of the level of physical activity.

Associations of green tea, coffee, and soft drink consumption with longitudinal changes in leukocyte telomere length

Whether beverage consumption is associated with longitudinal observation of telomere length remains unclear. We evaluated the association of green tea, coffee, and soft drink consumption with 6-year changes in leukocyte telomere length (LTL). The study included 1952 participants who provided whole blood samples for LTL assays during the baseline (year 2011-2012) and follow-up (year 2017-2018) periods and reported baseline information on consumption of green tea, coffee, and soft drinks. Robust regression analysis was used to analyze the association adjusted for potential confounding variables. In the results, an inverse association between green tea consumption and LTL changes from baseline, which indicate telomere shortening, was found; regression coefficient [95% confidence interval] was - 0.097 [- 0.164, - 0.029] for participants who daily consumed at least 1 cup of green tea compared with non-consumers (p value = 0.006). This association was stronger among women (versus men) and younger participants aged 50-64 years (versus older). However, a positive association between soft drink consumption and LTL shortening was observed among women (p value < 0.05). Coffee consumption was not associated with LTL changes. These findings suggested that green tea consumption may be protective against telomere shortening reflecting biological aging whereas coffee and soft drink consumption may not.

Coffee and Green Tea Consumption and Cardiovascular Disease Mortality Among People With and Without Hypertension

Background This study was conducted to examine the impacts of coffee and green tea consumption on cardiovascular disease (CVD) mortality among people with severe hypertension. Methods and Results In the JACC (Japan Collaborative Cohort Study for Evaluation of Cancer Risk), 18 609 participants (6574 men and 12 035 women) aged 40 to 79 years at baseline who completed a lifestyle, diet, and medical history questionnaire, and health examinations, were followed up until 2009. We classified the participants into four blood pressure (BP) categories: optimal and normal BP, high-normal BP, grade 1 hypertension, and grade 2-3 hypertension. A Cox proportional hazard model was used to calculate the multivariable hazard ratios with 95% CIs of CVD mortality. During the 18.9 years of median follow-up, a total of 842 CVD deaths were documented. Coffee consumption was associated with an increased risk of CVD mortality among people with grade 2-3 hypertension; the multivariable hazard ratios (95% CI) of CVD mortality were 0.98 (0.67-1.43) for <1 cup/day, 0.74 (0.37-1.46) for 1 cup/day, and 2.05 (1.17-3.59) for ≥2 cups/day, compared with non-coffee drinkers. Such associations were not found among people with optimal and normal, high-normal BP, and grade 1 hypertension. Green tea consumption was not associated with an increased risk of CVD across any BP categories. Conclusions Heavy coffee consumption was associated with an increased risk of CVD mortality among people with severe hypertension, but not people without hypertension and with grade 1 hypertension. In contrast, green tea consumption was not associated with an increased risk of CVD mortality across all categories of BP.

Health Effects of Soy Isoflavones and Green Tea Catechins on Cancer and Cardiovascular Diseases Based on Urinary Biomarker Levels

Plant polyphenols have various health effects. Genistein, which is abundant in soybeans, and epigallocatechin-3-gallate, which is abundant in green tea, are major flavonoids, a subclass group of polyphenols. Several epidemiological studies have shown that these flavonoids have beneficial effects against cancer and cardiovascular diseases. However, other studies did not show such effects. Several confounding factors, including recall bias, are related to these inconsistent findings, and the determination of metabolites in the urine may be useful in reducing the number of confounding factors. Equipment, which can be used by research participants to collect samples from a portion of voided urine within 24 h without the help of medical workers, has been developed for epidemiological investigations. Previous studies, in which flavonoid metabolites in these urine samples were measured, revealed that soy intake was correlated with a reduced risk of certain types of cancer and cardiovascular diseases worldwide. Although soybeans and green tea consumption may have protective effects against cancer and cardiovascular diseases, further clinical studies that consider different confounding factors are required to provide evidence for the actual impact of dietary flavonoids on human diseases, including cancer and cardiovascular diseases. One possible mechanism involved is discussed in relation to the downregulation of reactive oxygen species and the upregulation of 5'-adenosine monophosphate-activated protein kinase elicited by these flavonoids.

Consumption of coffee and tea with all-cause and cause-specific mortality: a prospective cohort study

BACKGROUND

Previous studies suggested that moderate coffee and tea consumption are associated with lower risk of mortality. However, the association between the combination of coffee and tea consumption with the risk of mortality remains unclear. This study aimed to evaluate the separate and combined associations of coffee and tea consumption with all-cause and cause-specific mortality.

METHODS

This prospective cohort study included 498,158 participants (37-73 years) from the UK Biobank between 2006 and 2010. Coffee and tea consumption were assessed at baseline using a self-reported questionnaire. All-cause and cause-specific mortalities, including cardiovascular disease (CVD), respiratory disease, and digestive disease mortality, were obtained from the national death registries. Cox regression analyses were conducted to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

After a median follow-up of 12.1 years, 34,699 deaths were identified. The associations of coffee and tea consumption with all-cause and cause-specific mortality attributable to CVD, respiratory disease, and digestive disease were nonlinear (all P nonlinear < 0.001). The association between separate coffee consumption and the risk of all-cause mortality was J-shaped, whereas that of separate tea consumption was reverse J-shaped. Drinking one cup of coffee or three cups of tea per day seemed to link with the lowest risk of mortality. In joint analyses, compared to neither coffee nor tea consumption, the combination of < 1-2 cups/day of coffee and 2-4 cups/day of tea had lower mortality risks for all-cause (HR, 0.78; 95% CI: 0.73-0.85), CVD (HR, 0.76; 95% CI: 0.64-0.91), and respiratory disease (HR, 0.69; 95% CI: 0.57-0.83) mortality. Nevertheless, the lowest HR (95% CI) of drinking both < 1-2 cup/day of coffee and ≥ 5 cups/day of tea for digestive disease mortality was 0.42 (0.34-0.53).

CONCLUSIONS

In this large prospective study, separate and combined coffee and tea consumption were inversely associated with all-cause and cause-specific mortality.

Causal relationship between tea intake and cardiovascular diseases: A Mendelian randomization study

Background

Although studies suggest that tea consumption is associated with a reduced risk of cardiovascular disease (CVD). There is no unified conclusion about the potential relationship between tea drinking and CVD. We used a two-sample Mendelian randomized (MR) analysis to systematically explore the causal relationship between tea intake and CVD subtypes for the first time. Furthermore the mediating effect of hypertension was also explored by a two-step MR.

Methods

Genetic instruments for tea intake were identified from a genome-wide association studies (GWAS) involving 447,485 people. Summary data on cardio-vascular disease came from different GWAS meta-analysis studies. In the first step we explored the causal effect of tea intake and CVD. In the second step, we examined the association of hypertension with heart failure and ischemic stroke and estimated the mediating effect of hypertension. Inverse variance weighted MR analysis was used as the primary method for causal analysis. A further sensitivity analysis was performed to ensure robustness of the results.

Results

One standard deviation increase in tea intake was associated with a 25% (OR = 0.75, 95%CI = 0.61–0.91, p = 0.003) lower risk of hypertension, a 28% (OR = 0.72, 95%CI = 0.58–0.89, p = 0.002) lower risk of heart failure, and a 29% (OR = 0.71, 95%CI = 0.55–0.92, p = 0.008) lower risk of ischemic stroke, respectively. And the association between tea drinking and the risk of heart failure and ischemic stroke may be mediated by hypertension. Sensitivity analyses found little evidence of pleiotropy.

Conclusion

Our two-sample MR analysis provided genetic evidence that tea intake was significantly associated with a reduced risk of hypertension, heart failure, and ischemic stroke, and that hypertension may be a potential mediator. Further large randomized controlled trials should be conducted to confirm the causal effect of tea consumption on cardiovascular disease risk.

Nutrition Guidelines for Improved Clinical Care

Given the importance of poor nutrition as a cause for human chronic disease, it is surprising that nutrition receives so little attention during medical school training and in clinical practice. Specific vitamins, minerals, fatty acids, amino acids and water in the diet are essential for health, and deficiencies lead or contribute to many diseases. Proper use of the dietary guidelines and nutrition facts labeling can improve nutritional status and lead to the consumption of a healthy diet. COVID-19 has altered access to nutritious foods for millions and increased awareness of the importance of diet and immune function. An improved appreciation for nutrition will improve the outcomes of clinical care.

Coffee and Arterial Hypertension

Purpose of Review

Coffee is a very popular drink and an estimated 2.25 billion cups worldwide are consumed daily. Such popularity of coffee makes it the most consumed drink next to water. Numerous studies have shown a beneficial effect of habitual and moderate coffee consumption on the functioning of the nervous, digestive, and cardiovascular systems, as well as on kidney function. Taking into account the very high prevalence of arterial hypertension in the world (31.1% of adults), much controversy has been raised about the influence of coffee consumption on blood pressure and the risk of arterial hypertension. Moreover, there have been extensive discussions about the safety of coffee consumption for hypertensive persons.

Recent Findings

There are over 1000 chemical compounds in coffee. The best characterized of these are caffeine, chlorogenic acid, trigonelline, kahweol, cafestol, ferulic acid, and melanoidins. These compounds have bidirectional influences on blood pressure regulation. The results of numerous studies and meta-analyses indicate that moderate and habitual coffee consumption does not increase and may even reduce the risk of developing arterial hypertension. Conversely, occasional coffee consumption has hypertensinogenic effects. Moderate habitual coffee consumption in hypertensive persons does not appear to increase the risk of uncontrolled blood pressure and may even reduce the risk of death from any cause.

Summary

Moderate and habitual consumption of coffee (1-–3 cups / day) does not adversely affect blood pressure in most people, including those with arterial hypertension.

Correlations between Coffee Consumption and Metabolic Phenotypes, Plasma Folate, and Vitamin B12: NHANES 2003 to 2006

Metabolic syndrome (MetS) is prevalent not only among the overweight and obese but also normal weight individuals, and the phenotype is referred to as a metabolically unhealthy phenotype (MUHP). Besides normal weight individuals, overweight/obese individuals are also protected from MetS, and the phenotype is known as a metabolically healthy phenotype (MHP). Epidemiological studies indicate that coffee and micronutrients such as plasma folate or vitamin B12 (vit. B12) are inversely associated with MetS. However, correlations among coffee consumption metabolic phenotypes, plasma folate, and vit. B12 remain unknown. Our objective was to investigate the correlation between coffee consumption, metabolic phenotypes, plasma folate, and vit. B12 as well as to understand associations between plasma folate, vit. B12, and metabolic phenotypes. Associations among coffee consumption metabolic phenotypes, plasma folate, and vit. B12 were assessed in a cross-sectional study of 2201 participants, 18 years or older, from 2003-2004 and 2005-2006 National Health and Nutrition Examination Surveys (NHANES). MUHP was classified as having > three metabolic abnormalities. Coffee consumption was not associated with metabolic phenotypes, but negatively correlated with several metabolic variables, including BMI (p < 0.001). Plasma folate was positively associated with MUHP (p < 0.004), while vit. B12 was inversely associated with MUHP (p < 0.035). Our results suggest the potential protective impact of coffee on individual components of MetS and indicate a positive correlation between coffee consumption and MUHP among overweight individuals. Identifying possible dietary factors may provide practical and low-cost dietary intervention targets, specifically for early intervention. Larger and randomized intervention studies and prospective longitudinal studies are required to further evaluate these associations.