Drinking tea has been linked to a wide range of health benefits, including improved cardiovascular health. However, many of the studies conducted have been solely observational, with no way of assessing the quantities of different component s of the tea. A recent randomized, double-blind, placebo-controlled study examined the effects of a standardized green tea extract on various cardiovascular risk factors.
The study included 111 healthy adult volunteers, of which half received a standardized capsule containing 100mg L-theanine and 200 mg of green tea extract (45% EGCG) twice daily and the other half received a placebo. Measurements of various cardiovascular risk factors were taken at baseline, after 3 weeks and after 3 months. These measurements included blood pressure, low-density lipoprotein (LDL) cholesterol levels, serum malondialdehyde levels (a marker of oxidative stress) and a marker of chronic inflammation (serum amyloid-a levels).
Following three weeks of supplementation, individuals receiving the green tea capsule showed significantly lower blood pressure levels (systolic blood pressure reduced by 5mmHg and diastolic by 4mmHg). The reduction in systolic blood pressure remained significant after 3 months as well. There was also a significant decrease in the inflammation and oxidative stress markers, with serum amyloid-a levels decreasing by 42% and serum malonaldehyde levels decreasing by 11.9%. In individuals with a high baseline cholesterol level, there was also a significant decrease in LDL cholesterol levels. This effect was more pronounced in men.
Overall the results of this study provide good evidence for the potential of green tea compounds (EGCG and L-theanine) for reducing a variety of cardiovascular risk factors, and improving overall cardiovascular health. EGCG and L-theanine may work together to reduce hypertension by promoting a relaxed state of mind and relaxing vascular smooth muscle. EGCG is also a powerful anti-inflammatory, and may reduce oxidative stress through its antioxidant properties.
Meri P, Mantz BS, Rowe CA, Bukowski JFm Oercival SS. 2008. Standardized capsule of Camellia sinensis lowers cardiovascular risk factors in a randomized, double-blind, placebo-controlled study. Nutrition: Online publication ahead of print.
For more information see EGCG Max and Zen Theanine
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