Q. Will increasing sun exposure to enhance vitamin D production cause skin cancer?

A. Although excess sun increases the risks of wrinkles and skin cancer, new medical evidence suggests some sunlight is beneficial. Sunlight prompts our bodies to make vitamin D. Luckily, the amount of sun needed to make vitamin D is much less than the amount that causes skin cancer.

Vitamin D is essential to building bones. It also regulates cell growth and is involved in immunity.

Research shows that vitamin D decreases the risk of many types of cancers. It prevents runaway cell proliferation often seen with cancer.

Vitamin D deficiency has been linked to immune system disorders including multiple sclerosis, rheumatoid arthritis and type 1 diabetes. It also may play a role in inflammation seen in heart and gum diseases. More research is still needed in these areas.

In recent years, deficiency has been observed in all age groups. In light of research showing vitamin D's potential to prevent diseases and the prevalence of deficiencies, experts recommend we get at least 1,000 International Units daily from a combination of sun, supplements and food.

Food sources include oily fish, milk and eggs. It's difficult to get enough vitamin D from food alone. As we age, our ability to absorb vitamin D from the sun decreases so those older than 50 may need supplements. Choose supplements containing vitamin D3, as this is the most effective form.

Some experts think we have gone overboard with sunscreen. While protecting ourselves from wrinkles and skin cancer, they say we are risking more deadly forms of cancer and other diseases. A balance is needed between the amount of sun that prevents vitamin D deficiency and the amount that prevents skin cancer.

Vitamin D experts recommend limited sun exposure. Skin should not turn red. For most people, 10 to 15 minutes daily of sun without sunscreen is adequate. If your skin is fair, 5 minutes is better. Dark skin absorbs less vitamin D from the sun, so people with dark skin may need 20 minutes. Individuals at high risk for skin cancer may be better off with supplements rather than sun exposure. Check with your dermatologist.

Exposing lots of skin for a short time works best. Shorts and T-shirt or a bathing suit provide adequate exposure. When your time is up, protect your skin and slather on the sunscreen!

Amy Tousman is a registered dietitian and certified diabetes educator. Hawai'i experts in traditional medicine, naturopathic medicine and diet take turns writing the Prescriptions column. Send your questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; islandlife@honoluluadvertiser.com; or fax 535-8170. This column is not intended to provide medical advice.