For decades we have heard about the dangers of sun exposure. Ultraviolet (UV) rays from the sun cause damage to the skin leading to premature aging and increased risks of skin cancer. With strong messages from medical organizations, many people have increased their sun protection habits, such as daily sunscreen and avoiding the sun.

Ideally, these changes have improved our health by decreasing cancer risk, but we are also blocking a major health benefit. In as little as 10 minutes, the sun’s UVB (a type of UV ray) rays can stimulate the production of 10,000 units of vitamin D. (The Recommended Dietary Allowence is 600 international units.) And more and more research is showing vitamin D to be a king of wonder-vitamins. Is the sun’s vitamin D benefit enough to outweigh its risks?

beach.gif Vitamin D has stirred up interest in the medical community because of research that has shown that it has protective effects against heart disease, osteoporosis, and several types of cancer, including breast, prostate, colon, and skin cancers. Of course, other vitamins have been hailed as heroes but fell short of their original promise. But vitamin D has held up under a good amount of research. The debate is now about where you should get your vitamin D.

Food Sources

Some of the highest sources of vitamin D are fish and fish liver oils. But Americans get the majority of their vitamin D from fortified foods like milk and orange juice. Even with fortified foods, it is difficult for the majority of people to get enough vitamin D through diet alone. You would have to drink about 50 glasses of milk to get the same amount of vitamin D that you get from 10-15 minutes of sun exposure.

Supplements

Vitamin D is available in supplement form, usually in a combination pill with calcium. An effective supplement would be able to increase blood levels of vitamin D. Vitamin D3 (cholecalciferol) is a preferred source of supplemental vitamin D. However, supplements do not provide anywhere near the amount of vitamin D that the sun can provide. High amounts of vitamin D supplementation have led to dangerously high levels of calcium in the body. Sun-created vitamin D, even at significantly higher levels, does not cause these problems.

Sun

The sun is believed to provide about 80% of your vitamin D supply. But even the sun’s benefits have some inconsistencies. The sun can create 10,000 units of vitamin D within 10 minutes for people with fair skin, but it may take 5-10 times longer in people with darker skin.

UVB rays are also weak and can be easily blocked by clouds, smog, and glass windows. During certain times of the year, in far north and far south regions (like Washington state and Vermont), between November and February, the sun’s UVB rays do not even reach the Earth’s surface. There is far less or no production of vitamin D during these times of year.

And of course for some, the risk of skin cancer leaves the sun out as a reasonable source for vitamin D.