Chinese analysts find green tea lowers blood cholesterol

Green tea is a widely consumed beverage, especially in Asia, and it may have important health promoting benefits. Epidemiologic studies have found an inverse association between green tea consumption and the risk of cardiovascular disease, a leading cause of morbidity and mortality worldwide.  It has also been found that subjects who consume more than two cups of green tea per day have a 22-33 percent lower risk of death from cardiovascular disease.

A variety of studies have investigated possible mechanisms by which green tea constituents could exert a cardioprotective effect. One important bioactive component in green tea is catechins which have been shown to inhibit the activity of important enzymes involved in cholesterol synthesis and to inhibit cholesterol absorption. 

Elevated blood levels of cholesterol are a risk factor for cardiovascular disease.  These epidemiologic and in vivo studies in animal models have led to the testing of the cholesterol-lowering effects of green tea and green tea extracts in a number of clinical trials in humans. However, the findings from these trials have been inconsistent, making it difficult to judge the benefits of green tea for cardiovascular health.

This uncertainty in our knowledge has led Chinese investigators to conduct a meta-analysis of randomized control trials of green tea on total and LDL-cholesterol. LDL-cholesterol, sometimes called “bad cholesterol,” is an important biomarker of heart disease risk.  A meta-analysis is a statistical procedure where the investigators summarize the overall effect of a particular treatment by combining the results from many different smaller studies to increase the power to detect a significant effect of the treatment.  In the case of green tea, the investigators found 14 studies (with a total of 1136 subjects enrolled) that could be combined to answer the question of whether green tea or green tea extract affected blood total and LDL-cholesterol.

This analysis showed that consumption of green tea led to a significant reduction in total blood cholesterol and LDL-cholesterol.  This finding is important because it suggests that incorporation of green tea into the diet could have a beneficial effect on cardiovascular health.

Source from:  Zheng X-X et al. American Journal of Clinical Nutrition 2011; 94:601-10.