Green tea polyphenol improves diastolic blood pressure and mood

An article published online on August 19, 2008 in the British Journal of Nutrition reported the results of a study of overweight or obese men, which found that supplementing with the green tea polyphenol known as epigallocatechin-3-gallate (EGCG) improved diastolic blood pressure and elevated mood.

Researchers from Great Britain sought to determine the effect of green tea on insulin resistance and metabolic risk factors in 88 overweight or obese nondiabetic men aged 40 to 65. Participants were randomly assigned to 400 milligrams EGCG or a placebo to be consumed twice per day for eight weeks. Glucose tolerance and metabolic risk factors, including blood pressure, were measured at the beginning and end of the treatment period. Mood was evaluated each week via a mood adjective questionnaire.

Although EGCG supplementation was not associated with improvements in insulin resistance or most metabolic risk factors in this study, diastolic blood pressure declined by 2.68 mmHg among men who received the compound in contrast with a decline of 0.058 mmHg in the control group. Those who received EGCG also reported a more positive mood and were not as tense than the placebo group by the end of the study.

The authors suggest that the effect of EGCG on blood pressure may play a role in some of the cardiovascular benefits that have been associated with the compound. EGCG has been shown to induce vasodilation in the arteries of rats, as well as stimulate the production of nitric oxide, a vasodilator, in endothelial cell cultures. Its effect on mood suggests that the compound may impact central nervous function, which may be mediated through gamma-aminobutyric acid receptors. The authors recommend further studies to explore the mechanisms of their findings.

RESOURCE/SOURCE:  www.lef.org on 8/27/08