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Black Tea May Protect Heart Health

According to the results of a large-scale Dutch population study, consumption of black tea (Camellia sinensis [L.] Kuntze, Theaceae) may decrease the risk of developing atherosclerosis, a hardening and narrowing of the coronary arteries that can contribute to heart attack, stroke, and other serious cardiovascular disease. The study showed that people who drank one to two cups of black tea a day had a 46 percent lower risk of developing severe atherosclerosis, while those who drank four or more cups a day had a risk reduction of 69 percent (Geleijnse et al., 1999). Tea drinking had no statistically significant effect on the development of mild or moderate atherosclerosis, and appeared to be more protective for women than for men.

The tea analysis was a sub-study of the Rotterdam Study, a prospective study of 7,983 Dutch men and women aged 55 and older that was designed to evaluate the relationship between dietary habits and a variety of chronic health conditions. After exclusion of study participants with a history of cardiovascular disease (which could have led to intentional dietary changes), 3,454 healthy people were eligible for the tea analysis. At the beginning of the study, participants completed detailed interviews about current and past health, diet, and lifestyle, and were examined radiographically to determine the extent of existing atherosclerosis. Changes in the degree of atherosclerosis were detected by radiography again after two to three years. Participants were followed for a median duration of 1.9 years.

The results of the Dutch tea study are in keeping with other research suggesting that tea flavonoids may protect against heart disease, although most earlier studies have focused on green tea, which has a higher flavonoid content. According to the investigators, black tea is the source of approximately half of the flavonoids consumed by Western populations, although they cite no source for this figure. In this study, one cup of tea was defined as 125 ml. Most people in the Netherlands take their tea without milk, and it is possible that the addition of milk to tea negatively affects the bioavailability of flavonoids.

Tea drinking among Westerners is associated with an overall healthier lifestyle and diet, and in general, the intake of tea in the Dutch study was higher among participants who were lean, were educated, smoked less, and consumed less alcohol, fat, and coffee. However, even after the data were adjusted for these and other possible confounding factors, the inverse association between tea consumption and severe atherosclerosis in this study remained statistically significant. - Evelyn Leigh, HRF

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[Geleijnse JM, Launer LJ, Hofman A, Huibert APP, Witteman JCM. Tea flavonoids may protect against atherosclerosis. The Rotterdam Study. Archives of Internal Medicine 1999; 159: 2170-2174.]

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