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
[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.] |
