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Green Tea and Skin Cancer
You’ve probably seen “green tea extract” listed as
an ingredient in skin care products, especially sunscreens. This makes
sense in light of the ever-growing scientific evidence suggesting that
green tea can protect against skin cancer.
Just be aware that most of the green tea/skin
cancer studies have been conducted on animals, not humans. That’s
because inducing skin cancer, a necessary step in testing the tea’s
protective abilities, is unethical in human subjects. So researchers use
hairless mice instead because they have skin that's remarkably similar
to human skin.
When green tea extract is given to these mice
before they are exposued to skin cancer carcinogens, either in their
drinking water or painted on their skins, the results are nothing short
of amazing:
Animal studies
Fewer skin tumors
For 50 days, two groups of mice were given drinking water that was
either plain or contained green tea extract. Then both groups were
injected with a powerful skin cancer inducer, followed by applications
of a tumor promoter. The mice that received the green tea extract
developed 44% fewer skin tumors.1
Less tumor growth
Two groups of mice were injected with a skin cancer initiator. Then
one group had a green tea catechin solution painted on their skins,
while the other group was left alone. Both groups were then exposed to a
tumor promoter. The mice that had the catechin solution painted on their
skins had 50%-84% less tumor growth.2
Less tumor multiplication
Two groups of mice were exposed to UVB radiation three times a week
for 24 weeks. Those that received green tea catechins in their drinking
water had 35% fewer new tumors, 55% less tumor growth and 63% less tumor
multiplication.3
Human studies
As any good researcher will tell you, the results gleaned from
animal tests don’t necessarily translate to the same results in humans.
And while there are few human studies of green tea’s effect on skin
cancer, two are worth mentioning:
Melanoma inhibited
In a test-tube study of green tea’s effects on melanoma (a
potentially deadly form of skin cancer), green tea extract decreased the
growth and multiplication of the human melanoma cells and increased
“cell suicide.”4
Radiation-induced skin toxicity decreased
In a study of 60 patients with cancer of the head, neck or pelvic
region, tea extracts were painted on the patients’ skin before they
received their radiation treatments. The tea extracts decreased the
duration of skin toxicity, a common and painful side effect of
radiation, by 5-10 days.5
While we certainly don’t suggest throwing out your
sunblock in favor of sipping green tea, it looks like green tea has the
potential to be a very effective weapon in the war against skin cancer!
Click here for a simplified look at the studies on
green tea's effect on skin cancer.
Footnotes:
1
Wang ZY, Khan WA, Bickers DR, et al. Protection against polycyclic
aromatic hydrocarbon-induced skin tumor initiation in mice by green tea
polyphenols. Carcinogenesis 1989;10(2):411-15.
2
Mukhtar H, Wang ZY, Katiyar SK, et al. Tea components: antimutagenic and
anticarcinogenic effects. Preventive Medicine 1992;21(3):351-60.
3Mantena
SK, Meeran SM, Elmets CA, et al. Orally administered green tea
polyphenols prevent ultraviolet
radiation-induced skin cancer in mice through activation of cytotoxic
T-cells and inhibition of angiogenesis in tumors. Journal of
Nutrition 2005; 135(12):2871-77.
4
Nihal M, Ahmad N, Mukhtar H, et al. Anti-proliferative and proapoptotic
effects of (-)-epigallocatechin-3-gallate on human melanoma. Int J
Cancer 2005;114(4):513-21.
5
Pajonk F, Riedisser A, Henke M, et al. The effects of tea extracts on
proinflammatory signaling BMC Med 2006;4:28.
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Nadine Taylor, M.S., R.D. presents
GreenTeaLibrary.com,
the most comprehensive collection of scientific information
describing the health benefits of green tea. |
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