Monday 25 July 2016

Association of Green Tea with Risk of Coronary Heart Disease (CHD)

Abstract

Prospective studies on the association of green tea with risk of coronary heart disease (CHD) incidence were scarce. This study examined whether green tea can reduce CHD incidence and have a beneficial effect on CHD-related risk markers in middle-aged and older Chinese population. We included 19 471 participants who were free of CHD, stroke or cancer at baseline from September 2008 to June 2010, and were followed until October 2013. Cox proportional hazard models were used to examine the hazard ratios (HR) of CHD incidence in relation to green tea consumption. Linear regression models were used to evaluate the effect of green tea on 5-year changes of CHD-related biomarkers. Compared with non-green tea consumers, the multivariable-adjusted HR for CHD was 0.89 (95% CI, 0.81-0.98) in green tea consumers. Particularly, the reduced risk of CHD incidence with green tea consumption was more evident among participants who were male, more than 60 years old, overweight, or with diabetes mellitus. In addition, green tea consumption improved multiple CHD-related risk markers including total cholesterol, HDL-cholesterol, triglycerides, mean platelet volume, and uric acid. In conclusion, green tea consumption was associated with a reduced risk of CHD incidence in the middle-aged and older Chinese populations, and the association might be partly due to altered CHD-related biomarkers.

Cardiovascular disease (CVD) has become the leading cause of death and continues to exert a heavy burden in China. The number of patients with CVD increased to 290 million in 2014 with one out five Chinese adults suffering from the disease1. Coronary heart disease (CHD) accounts for the greatest proportion of CVD, and the prevalence of Chinese people with CHD is increasing substantially due to ageing, imbalanced diets, unhealthy behaviors and the raising standard of living. Thus, early prevention and control of CHD has become an extremely important public health concern.

Tea, a beverage made from leaves of Camellia sinensis, is the second most consumed beverage worldwide, only close to plain water. Tea was generally categorized into black, green and oolong tea according to the manufacturing process. Black tea, which covers about 78% of the total tea production, is usually consumed in the West; whereas green tea, which covers 20%, is consumed primarily in Japan, China and other East Asian countries5. A recent meta-analysis of prospective studies based mainly on evidence from black tea or unspecified tea showed that tea consumption was associated with a reduced risk of CHD, and found that the associations between tea consumption and cardiovascular outcomes differ according to sex, ethnicity, and the type of tea consumed. On the contrary, data on the association between green tea and CHD was limited and inconclusive. Several cohort studies have suggested an inverse association between green tea and CVD mortality. Although dose-response relationship between green tea and risk of CHD was reported in case-control and cross-sectional studies only two cohort studies have examined the impact of green tea consumption on risk of CHD incidence and no significant association was observed. On the other hand, favorable changes in CHD-related biomarkers, such as blood pressure, LDL cholesterol and glucose levels, were reported with green tea in randomized controlled trials which suggested a possible protective effect of green tea against CHD. However, most existing studies have only focused on one aspect: either green tea versus CHD, or green tea versus biomarkers; seldom studies have so far examined both of them on a same population.

Because of the high consumption of green tea in China and relatively high rate of CHD incidence and mortality, exploring the health effects of green tea on CHD might provide clues to resolve an important public health issue. Therefore, we aimed to 1) verify the relationship between green tea and CHD incidence in the Dongfeng-Tongji cohort; 2) examine whether the association between green tea and CHD was modified by differences in population characteristics and disease status; and 3) evaluate the effect of green tea on changes of multiple CHD-related biomarkers.

Resource: http://www.ncbi.nlm.nih.gov/
Resource: http://www.nutritionforest.com/

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