The time of day you’re in the sun determines how much vitamin D your body can make. Dr. Grant points out that we can’t convert vitamin D from UVB radiation unless the sun is high in the sky. So get outside for 15-30 minutes before or after lunch each day. If you go outdoors at other times, you’ll need a longer exposure to get the same protection. During the winter, the sun isn’t high enough or close enough for your body to make vitamin D from sunlight. That’s when you need to rely on supplements and put away your sunscreen.

Four hundred IU a day is the bare minimum vitamin D you need. But you may want to begin with as much as 10,000 IU for a month or two to raise depleted levels. If you haven't been getting much sunlight, ask your doctor to test you for vitamin D deficiency with a test called 25-hydroxyvitamin D — or 25(OH)D. Then, if you’re deficient, have him or her monitor your levels as you take large doses.

The problem with sunscreens
A lot of them contain some chemicals that promote the production of dangerous free radicals, and other chemicals with estrogenic effects. In fact, most of these ingredients are banned in Europe. Only buy products with titanium dioxide or zinc oxide. They’re safe and offer effective protection. You can find them in health food stores and some pharmacies.

Sunscreens won't work if they have less than SP-15 protection or if they're out of date. Check the expiration date on your sunscreen and replace it if it’s old.

Your diet protects your skin
Antioxidants in your diet protect your skin from becoming damaged by UV radiation and from nonmelanoma skin cancers. These include carotenoids (vitamin A), tocopherols (vitamin E), ascorbate (vitamin C), flavonoids, and omega-3 fats (fish oil, flax oil). Include plenty of fresh fruits and vegetables into your diet.

In Norway, where there’s little sunlight during the winter months, vitamin D deficiency is common. More than two-dozen Norwegians were given a diet high in fatty fish and cod liver oil — all high in vitamin D. In fact, the participants were given more than 54 times the recommended daily requirements. All of the people who continued eating diets high in vitamin D were able to sustain sufficient vitamin D in their blood throughout the winter.

It's important to understand and remember that sunlight is your ally, not your enemy. Be smart. Get outdoors and increase your vitamin D. For more information on sunlight, vitamin D, and cancers, read some of the articles by cancer researcher Ralph Moss, PhD, at www.cancerdecisions.com.

Hughes, A.M., B.K. Armstrong, C.M. Vajdic, J. Turner, A.E. Grulich, L. Fritschi, S. Milliken, J. Kaldor, G. Benke, and A. Kricker. "Sun exposure may protect against non-Hodgkin lymphoma: a case-control study." Int J Cancer, 2004;112:865-71.

Grant, W.B. "An estimate of premature cancer mortality in the United States due to inadequate doses of solar ultraviolet-B radiation," Cancer, 2002;94:1867-75.

Nowson, C.A. "Vitamin D in Australia. Issues and recommendations," Aust Fam Physician, 2004 March;33(3).

Brustad, M., et al. "Vitamin D status in a rural population of northern Norway with high fish liver consumption," Public Health Nutr, 2004, September; 7(6).

Sies, H., and W. Stahl. "Nutritional protection against skin damage from sunlight,” Annual Review Nutr, 2004;24.

Moss, Ralph, Ph.D., www.cancerdecisions.com.