< ? Texas Blogs # >

Sunblock and skin cancer: Not the relationship you thought there was.

Here's an interesting article:

http://www.mercola.com/2003/jul/2/sunblock_cancer.htm

Read it carefully. What he is saying (if I understand him correctly) is this:

1. You need vitamin D. Sunlight on the skin (up to an hour a day) is the most important source of vitamin D. The other source of vitamin D is the food you eat.

2. Vitamin D may have a role in preventing skin cancer and certain other cancers as well (breast and prostate).

3. Using sunblock prevents production of vitamin D by your body. Therefore, using sunblock could actually increase your risk of getting cancer. Yow.

The biggest issue with vitamin D is that, at the levels thought to provide protection from cancer, it depletes the level of calcium in the body. This can lead to problems with osteoporosis, but you can take supplements to deal with this.

What Dr. Mercola seems to be recommending is this:

1. Build up your sun exposure in spring and summer so you can get an hour of sunlight on your body every day, without sunblock. Start slow and AVOID GETTING SUNBURNED. It doesn't have to be an hour straight - several periods of exposure adding up to an hour is enough. In other places, I have read that (for caucasians, anyway), all that needs to be exposed in summer is the arms and the face, not the whole body. One source says that for caucasians twenty minutes is enough to provide all the vitamin D you need for the day. I wish these guys could come to an agreement, but it looks like 20 to 60 minutes total would be a good idea, more than that is probably asking for trouble with sunburn and increased cancer risk.

2. If you are staying out of the sun, and for everyone in winter, take fish oil as a supplement. African-Americans and others with dark skin living in temperate latitudes should probably take fish oil routinely rather than increase sun exposure, because the melanin in your skin cuts down on the amount of vitamin D produced. (Read this in other places, not in the article - some scientists think that caucasians are humans that lost pigmentation as an adaptation to allow their bodies to produce enough vitamin D in relatively sunless northern latitudes. The jury is still out on that one.) Anyway, Mercola recommends cod liver oil for everybody, both for the vitamin D in it and for the Omega-3 fatty acids. I also read that in the winter, at the latitiude of Boston, a fair-skinned person could stand outside naked all day and not get enough sun to produce any vitamin D. That person would also probably have a severe case of frostbite and an arrest record by the end of the day. Take your cod-liver oil.

3. Reduce your consumption of foods containing Omega-6 fatty acids. If your favorite snack is sunflower seeds, you might want to reconsider that, or reduce your consumption of them/balance your consumption of sunflower seeds by eating more fish containing Omega-3 fatty acids. Remember that corn oil, safflower oil, etc. (he lists them in the article) are almost pure Omega-6 fatty acids and also need to be reduced so that you get as close as possible to a 1:1 ratio of consumption. This is coming out more and more as being important to prevention of certain cancers.

Sunlight is also a key factor in preventing some kinds of depression, by the way. If you're a person prone to the blues, taking a short walk in the sun every day at lunch time might be a good thing to do, and cheaper than medication.

Dr. Mercola points out the irony in our (appropriate) concern about cancer and exessive sun exposure, while at the same time it appears that moderate exposure to sun may actually help to prevent skin cancer and sunblock use could be a problem.

So -- if I got the doc's ideas right -- get a little sun every day(without sunblock) but don't get burned, eat more fish, manage the kinds of fatty acids you are consuming, and take take cod liver oil and a good multivitamin (I would add, one with calcium in it). You won't be a bronzed deity, but you might be happier and less likely to have to deal with cancer.

Here is a different view on the subject of vitamin D and sunblock use, in a 1995 Australian study. While I don't think this negates Dr. Mercola's advice about getting a little direct sun every day and getting plenty of vitamin D through food and supplements, it might make you feel a little better about using sunscreen.

Last update: 4/17/2006; 10:43:38 PM.