Monday, August 29, 2005

Stop Using Sunscreen

A very interesting article is in this month's Harvard Magazine (not online yet). The theory is that by using sunscreen, people prevent their bodies from producing Vitamin D, and thereby create a higher risk of several types of cancer, far outweighing the risk of skin cancer. Here are some excerpts:
According to a new theory, sealing our skins off from the sun may cause more cancer deaths than it prevents.

Associate professor of medicine Edward Giovannucci notes that UV-B radiation, the source of suntan and sunburn, is also the component of sunlight that enables human skin . . . to synthesize the "sunshine vitamin" -- D -- used by every type of cell in the human body. Animal research has associated a lack of vitamin D with multiple sclerosis, osteoporosis, and pathological processes that underlie several forms of cancer, including those of the colon, breast, prostate, and digestive tract . . . .

"If you look at the cancers as a group," says Giovannucci . . . "you'll see that 30 people dies of these cancers for every one who dies of skin cancer."
The article then discusses several key pieces of evidence:

1) A recent study shows Vitamin D's role in preventing cell proliferation, etc.

2) Northeastern people have higher rates of colon cancer.

3) Fat people have higher rates of cancer along with lower levels of vitamin D (which is fat-soluble).

4) Black people have much lower levels of vitamin D and higher rates of cancer, particularly prostate cancer. Giovannucci says that in a study of the Health Professionals sample, he was able to control for a wide variety of variables affecting the rates of cancer for white vs. black people, but "the only factor we found that showed a significant difference was vitamin D levels."

Also worth noting: 20 minutes in the sun can produce 10,000 units of vitamin D, which is the equivalent of drinking 100 glasses of fortified milk.

In concluding, Giovannucci says: "More sun, and higher rates of vitamin D, correlate with fewer cancers. It might ultimately prevent only a fraction, perhaps 30 percent, of those cancers it seems to affect. But that would still be vastly more cases than any skin cancers it causes. I don't recommend that people go out and get sunburned -- use common sense. But if the studies hold up, vitamin D will be a relatively important factor, since it affects such a large number of cancers. It may be time to rethink the message we are sending about sunlight."


Post a Comment

Subscribe to Post Comments [Atom]

<< Home