Tonic in a Teapot
Studies show that the EGCG in tea acts as a natural inhibitor of angiotensinconverting enzyme, or ACE, which is associated with high blood pressure. taining 79 percent fat, and some of the group also drank black tea. Drinking the tea mitigated much of the adverse blood vessel reaction to the high-fat meal. Another study of 302 men and 210 women in Japan found an inverse relationship between drinking green tea and atherosclerosis in the men, though not in the women.4 Hypertension, or high blood pressure, is a major risk factor for heart attacks and strokes. In vitro studies show that tea has vasodilation activity, which would be expected to lower blood pressure. The favorable
Researchers attribute tea’s stroke-protective properties to its stimulation of nitric oxide metabolism. impact of tea on the lining, or endothelium, of blood vessels also helps guard against hypertension. Clinical trials of tea intake in human subjects, however, have failed to replicate those results. One reason for the discrepancy may be that most of the human studies involved subjects who did not (go figure) have high blood pressure.5 On the other hand, an eight-year longitudinal study of 1,500 middleaged people in Taiwan found that those who drank more than 20 ounces a day of green or oolong tea for more than a year showed a 65 percent reduced risk of hypertension. Those who drank no tea showed no risk reduction, and the beneficial effects of drinking tea didn’t show up for a year.6 Studies show that the EGCG in tea acts as a natural inhibitor of angiotensinconverting enzyme, or ACE, which is associated with high blood pressure. Drugs that act specifically on ACE are used to treat high blood pressure. Studies using rats as subjects demonstrate that green tea inhibits the intestinal absorption of sodium, which would also lower blood pressure.7
Inflammation is a cornerstone of cardiovascular disease. Most heart attacks and strokes are initiated by a clot that blocks blood flow in an already occluded artery. A recent study of healthy nonsmoking men, aged 18 to 55, randomly assigned them to either a group drinking black tea or a placebo group.8 After six weeks those in the tea group had significantly reduced tendency toward internal blood clotting, along with lower levels of the inflammation-related C-reactive protein. Stroke, too, is linked to high blood pressure. A clinical investigation of 5,910 women aged 40 and over found that the incidence of stroke was 5.5 times higher for women who didn’t drink green tea than for those who drank five or more cups daily.9 An investigation of 7,730 men found a 33 percent risk reduction for stroke among tea drinkers but not among those who didn’t drink tea. Researchers attribute tea’s antistroke properties to its stimulation of nitric oxide metabolism, which prevents formation of internal clots and helps regulate blood pressure.10
Can Tea Save Your Brain? Several studies point to tea’s protective effects on brain function. They show that drinking tea leads to a rapid increase in alertness and in-
206 MARCH 2008 \ www.ironmanmagazine.com
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