Tea and Artery Function


“Tea and Artery Function” Our endothelium, the inner lining
of our blood vessels that controls the function of
every artery in our body, appears to play a critical role
in a variety of human disorders, including peripheral vascular disease,
stroke, heart disease, diabetes, kidney failure, cancer,
and blood clots. Unfortunately, endothelial cells
only live about 30 years, and their replacements don’t
seem to function as well, so as men and women approach
the ages of 40 and 50 there is a progressive decline
in endothelial function. At age 50 or 60, we can no
longer tolerate the risk-factor burden that we were once able
to tolerate as teenagers, thanks to this progressive decline
in endothelial function. But that’s what we
used to think. There are increasing data,
to suggest that age is NOT an immutable risk factor, In a Chinese population study, for example, they did not see the
progressive decline. The older Chinese in their 60’s
had the arterial function of young folks in their 20’s. These data suggest that
progressive endothelial dysfunction is not an inevitable
consequence of aging, but might be related to prolonged
exposure to environmental factors more prevalent in Westernized
countries than in China. What could it be? Well, traditional Chinese
diets include green tea, which has been shown to have
a beneficial effect on endothelial function within
30 minutes of consumption, and lasting about two hours. It wasn’t the caffeine,
which alone had no effect. They suspect it’s the flavonoid
phytonutrients in the tea leaves. Black tea, appears to work
about just as well as green tea, but then why is green tea associated
with lower heart disease risk, but black tea not? In fact, in two British studies
tea consumption was associated with an increased risk of
coronary artery disease. Maybe it’s because the Brits
drink their tea with milk, whereas green tea is
typically drank straight. If only there was a country
that drank black tea, but without milk. There is, the Netherlands, and in those studies,
black tea was associated with the same drop in risk
as the green tea studies, so maybe it is the milk. But you really can’t know
until you put it to the test. They found the addition of
milk to black tea completely prevents the
biological activity of tea in terms of improvement of
endothelial function. And so that could explain it. It appears casein
is the culprit, the milk protein, casein- though soy protein was recently found
to have the same nutrient binding effect. The European Society of Cardiology
issued a press release about the study showing the
protective effect of tea was totally wiped
out by adding milk, and suggested consumers should
consider cutting down. Milk-drinkers were not amused, “as long as the reported results
are not confirmed in a fair number of humans who drink their tea
outside the lab setting, we will continue to
add milk to ours.” The researchers responded,
challenging the notion that their study wasn’t
big enough. They had 16 people, and the
results were highly significant. Across those 16 people,
the addition of milk to tea not only reduced, but completely
blunted the effects of the tea. And, uh, the rationale for
drinking tea in a lab setting was because they were
doing an experiment. Were they supposed to
drag the equipment to a Starbucks or something? As doctors, the milky tea
drinkers asserted, just as we would not prescribe
a new drug to patients if it was studied only
in one small study, milk abstinence should not
be recommended to tea drinkers… apparently forgetting that the
reason we don’t prescribe drugs without overwhelming evidence
is because drugs can kill, so the benefits better
outweigh the risks, but what’s the downside of
a little milk abstinence?