"Preventing Prostate Cancer with Green Tea" Prostate cancer is a leading cause
of illness and death among men in the Western world, but the prostate cancer rates in Asia
can be as much as ten times lower. Maybe genetically they're just
that much less likely to get it? No, Japanese and Chinese Americans
have high prostate cancer rates as well. In the U.S., up to nearly one
in three men in their 30s already have small prostate
cancers brewing, and that grows to nearly two thirds
of American men by their 60's. On autopsy, most older men
were found to have unknown cancerous
tumors in their prostates. What's remarkable is that Asian men
seem to have the same prevalence of these hidden, latent prostate
cancers on autopsy, but the tumors don't tend to grow
enough to cause problems. In Japan, men die with their tumors
rather than from their tumors. Of course, that's changing as Asian populations
continue to Westernize their diets. What is it about Western diets
that's fueling cancer growth? Well, it could be carcinogens in the diet
accelerating the growth of cancer. The typical U.S.
Diet is rich
in animal fats and meats, but it could also be something
protective in Asian diets that's slowing the cancer growth, like fruits
and vegetables, soy foods, or green tea. How might one figure out if there
is a link between tea consumption and the risk and progression
of prostate cancer? Well, you could see if tea drinkers tend
to get less cancer in the future and if cancer victims tended
to have drank less tea in the past. Dozens of studies have done just that,
and although the results were mixed, overall tea consumption was associated
with a lower risk of prostate cancer, and so tea consumption might
indeed play a protective role.
But just because tea drinkers get less cancer
doesn't mean it's necessarily the tea. Maybe tea drinking is just a sign
of a more traditional lifestyle. Maybe tea drinkers are
less likely to be patrons of the thousand KFC outlets
now in Japan for example. To control for as many factors as possible,
you could perform in vitro studies in a lab, where you take everything
else out of the equation except green tea and
prostate cancer by dripping green tea compounds directly
onto prostate cancer cells in a Petri dish, which can cause them
to self-destruct.
But are enough green
tea compounds absorbed into our blood stream
when we drink it? Looks like it takes about a concentration
of 40 picomoles per milliliter to cut the viability of human prostate
cancer cells more than half in a Petri dish. How much green tea
would men have to drink to get concentrations that
high in their prostate glands? Well, if you have men drink
6 cups of green tea a day before undergoing prostate removal
surgery, they can indeed build up that 40 picomole cancer-stopping
concentration in their prostate tissue. That may explain why some studies
failed to find an association between tea drinking and cancer. In the U.S. for example, the high tea
drinking group may be defined as more than 5 cups of tea a week,
which didn't seem to do much. But in Japan, the high tea drinking
group can be 5 or more cups a day, which appeared to cut the risk of
aggressive prostate cancer about in half, not apparently by preventing the formation
of the cancer in the first place, but perhaps by slowing or
stopping the cancer's growth. If green tea can stop the
growth of prostate cancer, why not try giving green tea to prostate
cancer patients to see if it will help, which we'll explore next…
