"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?