Green tea consumption and the risk of coronary heart disease: A systematic review and meta-analysis of cohort studies.

BACKGROUND AND AIMS: Conflicting evidence exists regarding the association between green tea consumption and the risk of coronary heart disease (CHD). We performed a meta-analysis to determine whether an association exists between them in cohort studies. METHODS AND RESULTS: We searched the PubMed and EMBASE databases for studies conducted until September 2022. Prospective cohort studies that provided relative risk (RR) estimates with 95% confidence intervals (CIs) for the association were included. Study-specific risk estimates were combined using a random-effects model. A total of seven studies, with 9211 CHD cases among 772,922 participants, were included. We observed a nonlinear association between green tea consumption and the risk of CHD (P for nonlinearity = 0.0009). Compared with nonconsumers, the RRs (95% CI) of CHD across levels of green tea consumption were 0.89 (0.83, 0.96) for 1 cup/day (1 cup = 300 ml), 0.84 (0.77, 0.93) for 2 cups/day, 0.85 (0.77, 0.92) for 3 cups/day, 0.88 (0.81, 0.96) for 4 cups/day, and 0.92 (0.82, 1.04) for 5 cups/day. CONCLUSIONS: This updated meta-analysis of studies from East Asia suggests that green tea consumption may be associated with a reduced risk of CHD, especially among those with low-to-moderate consumption. Additional cohorts are still needed before we could draw a definitive conclusion. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022357687.

Green tea consumption and the risk of stroke: A systematic review and meta-analysis of cohort studies.

OBJECTIVES: Epidemiologic studies are inconsistent regarding the association between green tea consumption and the risk of stroke. We performed a meta-analysis to determine whether an association exists between them in cohort studies. METHODS: We searched the PubMed and Embase databases for studies conducted from 1966 through September 2022. Prospective cohort studies that provided relative risk (RR) estimates with 95% confidence interval (CI)s for the association were included. Study-specific risk estimates were combined by using a random-effects model. RESULTS: A total of five studies, with 11 421 stroke cases among 645 393 participants, were included in the meta-analysis. The summary RR indicated a significant association between highest green tea consumption and reduced risk of stroke (summary RR: 0.74; 95% CI, 0.66-0.83). In the dose-response analysis, we observed a nonlinear association between green tea consumption and the risk of stroke (P for nonlinearity = 0.0000). Compared with non-consumers, the RRs (95% CI) of stroke across levels of green tea consumption were 0.91 (0.89-0.94) for 150 mL/d, 0.84 (0.80-0.89) for 300 mL/d, 0.79 (0.74-0.84) for 500 mL/d, 0.77 (0.72-0.82) for 900 mL/d, and 0.84 (0.77-0.91) for 1500 mL/d. CONCLUSIONS: This meta-analysis suggests that green tea consumption is inversely associated with the risk of stroke, especially among those with moderate consumption. Our results support recommendations for green tea consumption to the primary prevention of stroke.

Low-dose green tea intake reduces incidence of atrial fibrillation in a Chinese population.

The aim of the present study was to assessthe association between green tea intake and incidence of atrial fibrillation (AF) in a Chinese population. A total of 801 (mean age: 62 years; 56% male) subjects were enrolled: 401 AF patients and 400 controls. All subjects completed a questionnaire and the associations between their green tea drinking habits and incidence of AF were assessed using the odds ratio (OR) and binary logistic regression. After multivariate adjustment, green tea intake presented as a protective factor against the incidence of AF (OR: 0.349, 95% CI: 0.253-0.483, P < 0.001). The green tea protection showed downward trend with increasing green tea intake (P for the trend= 0.001). Low frequency, low concentration, short-term tea consumption was classified as low-dose green tea intake. Green tea intake decreased the incidence of both paroxysmal AF (OR: 0.307, 95% CI: 0.216-0.436, P < 0.001) and persistent AF (OR: 0.355, 95% CI: 0.261-0.482, P < 0.001) and may be associated with a decreased incidence of AF. This study suggests that low-dose green tea intake strongly protects against AF.

Habitual coffee consumption and risk of cognitive decline/dementia: A systematic review and meta-analysis of prospective cohort studies.

OBJECTIVE: Findings from epidemiologic studies of coffee consumption and risk for cognitive decline or dementia are inconclusive. The aim of this study was to conduct a meta-analysis of prospective studies to assess the association between coffee consumption and the risk for cognitive decline and dementia. METHODS: Relevant studies were identified by searching PubMed and Embase databases between 1966 and December 2014. Prospective cohorts that reported relative risk (RRs) and 95% confidence intervals (CIs) for the association of coffee consumption with dementia incidence or cognitive changing were eligible. Study-specific RRs were combined by using a random-effects model. RESULTS: Eleven prospective studies, including 29,155 participants, were included in the meta-analysis. The combined RR indicated that high coffee consumption was not associated with the different measures of cognitive decline or dementia (summary RR, 0.97; 95% CI, 0.84-1.11). Subgroup analyses suggested a significant inverse association between highest coffee consumption and the risk for Alzheimer disease (summary RR, 0.73; 95% CI, 0.55-0.97). The dose-response analysis, including eight studies, did not show an association between the increment of coffee intake and cognitive decline or dementia risk (an increment of 1 cup/d of coffee consumed; summary RR, 1.00; 95% CI, 0.98-1.02). CONCLUSIONS: The present study suggests that higher coffee consumption is associated with reduced risk for Alzheimer disease. Further randomized controlled trials or well-designed cohort studies are needed to determine the association between coffee consumption and cognitive decline or dementia.

Green tea polyphenol epigallocatechin-3-gallate inhibits TNF-α-induced production of monocyte chemoattractant protein-1 in human umbilical vein endothelial cells.

AIMS: Epigallocatechin-3-gallate (EGCG), a major catechin found in green tea, displays a variety of pharmacological properties and recently received attention as a prospective dietary intervention in cardiovascular diseases (CVD). This study was conducted to test the hypothesis that EGCG was able to inhibit tumor necrosis factor-α (TNF-α)-induced production of monocyte chemoattractant protein-1 (MCP-1) in human umbilical vein endothelial cells (HUVECs) and investigated the underlying molecular mechanisms. METHODS: The inhibitory effect of EGCG on TNF-α-induced expression of MCP-1 was measured using ELISA and RT-qPCR. The effect of EGCG on TNF-α-induced nuclear factor-kappa B (NF-κB) activation was investigated by western blot and luciferase assays. Monocyte adhesion assay was detected by microscope. RESULTS: EGCG significantly suppressed the TNF-α-induced protein and mRNA expression of MCP-1. Investigation of the mechanism suggested that EGCG suppressed the TNF-α-mediated NF-κB activation. In addition, the 67-kD laminin receptor (67LR) was involved in EGCG-mediated suppression of MCP-1 generation. Furthermore, EGCG potently inhibited monocyte adhesion to activated HUVECs. CONCLUSION: EGCG suppresses TNF-α-induced MCP-1 expression in HUVECs. This effect was mediated by 67LR and was via the inhibition of NF-κB activation. Our results demonstrated that EGCG might be a possible medicine for CVD prevention and treatment.

Flavonol intake and stroke risk: a meta-analysis of cohort studies.

OBJECTIVE: Epidemiologic findings are inconsistent regarding the association between flavonol intake and the risk for stroke. The aim of this study was to determine whether an association exists between them in observational studies. METHODS: We searched the PubMed and EMBASE databases for studies conducted from 1966 to August 2013. Prospective cohort studies that provided relative risk (RR) estimates with 95% confidence intervals (CIs) for the association between flavonol intake and risk for stroke were included. A random effects model was used to combine study-specific risk estimates. RESULTS: The meta-analysis included eight studies, with 5228 stroke cases among 280 174 participants. The summary RR indicated a significant association between highest flavonol intake and reduced risk for stroke (summary RR, 0.86; 95% CI, 0.75-0.99). Furthermore, an increase in flavonol intake of 20 mg/d was associated with a 14% decrease in the risk for developing stroke (summary RR, 0.86; 95% CI, 0.77-0.96). Subgroup analyses suggested a significant inverse association between highest flavonol intake and stroke risk among men (summary RR, 0.74; 95% CI, 0.56-0.97) but not women (summary RR, 0.99; 95% CI, 0.85-1.16). CONCLUSIONS: Higher dietary flavonol intake is associated with a reduced risk for stroke, especially among men. Our results support recommendations for higher consumption of flavonol-rich foods to prevent stroke.

Black and green tea consumption and the risk of coronary artery disease: a meta-analysis.

BACKGROUND: Epidemiologic studies are inconsistent regarding the association between tea consumption and the risk of coronary artery disease (CAD). OBJECTIVE: The objective was to perform a meta-analysis to determine whether an association exists between tea consumption and total CAD endpoints in observational studies. DESIGN: We searched PUBMED and EMBASE databases for studies conducted from 1966 through November 2009. Study-specific risk estimates were combined by using a random-effects model. RESULTS: A total of 18 studies were included in the meta-analysis: 13 studies on black tea and 5 studies on green tea. For black tea, no significant association was found through the meta-analysis [highest compared with lowest, summary relative risk (RR): 0.92; 95% CI: 0.82, 1.04; an increment of 1 cup/d, summary RR: 0.98; 95% CI: 0.94, 1.02]. For green tea, the summary RR indicated a significant association between the highest green tea consumption and reduced risk of CAD (summary RR: 0.72; 95% CI: 0.58, 0.89). Furthermore, an increase in green tea consumption of 1 cup/d was associated with a 10% decrease in the risk of developing CAD (summary RR: 0.90; 95% CI: 0.82, 0.99). CONCLUSIONS: Our data do not support a protective role of black tea against CAD. The limited data available on green tea support a tentative association of green tea consumption with a reduced risk of CAD. However, additional studies are needed to make a convincing case for this association.