By Judy Rupp, Columnist
When Holly learned about the dangers of skin cancer, she regretted the hours she had spent on the beach as a teenager and started covering herself with sunscreen every day.
Recently, she learned her days in the sun may not have been a complete loss after all. While by no means ready to return to her sun baking ways, she has decided to venture into the sun, unprotected, for 10 to 15 minutes several times a week in order to protect herself from breast, ovarian, colon and other forms of cancer.
Holly is not alone. Americans have heard the skin cancer story. And the facts have not changed: cumulative exposure to the sun is the number one risk for basal and squamous cell skin cancers (which is common but rarely life threatening). Intermittent, intense exposure to ultraviolet radiation is believed to be the major risk factor for malignant melanoma, a dangerous cancer that takes the lives of eight thousand Americans every year.
In the past several years, researchers have documented widespread deficiencies of vitamin D, the sunshine vitamin, while other studies have indicated vitamin D deficiency may increase the risk of various cancers and chronic medical conditions such as hypertension, multiple sclerosis, diabetes and heart disease.
One study presented at the annual meeting of the American Association for Cancer Research (April, 2006) concluded at least half of American adults are deficient in vitamin D (defined as less than 20 nanograms/milliliter) and these individuals could lower their risk of breast, colon and other cancers by increasing their intake of vitamin D-rich foods or spending more time in the sun.
The recommended daily allowance for vitamin D is 400 IU (600 for persons age 70 and over), and many scientists believe it should be much higher. Your best dietary sources are fortified milk (98 IU per cup) and ready-to-eat cereal (40 to 50 IU per cup).
Supplements typically come in 400 IU doses, but doctors believe there is a risk of overdosing at levels greater than 2,000 IU a day. The easiest way to get vitamin D is through exposure to sunlight.
Vitamin D has long been known to play a major role in maintaining healthy bones. And at least since the 1930s, large observational studies have noted the incidence of breast, prostate, colon and other cancers is lower in areas close to the equator than in less sunny climates.
Vitamin D receptors are located throughout the body, and the vitamin is believed to be a potent inhibitor of cancer cell growth. It also plays a role in regulating the immune system and, as a result, may offer benefits against autoimmune disorders such as multiple sclerosis.
Research has shown vitamin D can lower blood pressure and reduce inflammation. A study published in Archives of Internal Medicine found a higher prevalence of hypertension, diabetes, obesity and high triglycerides in vitamin D deficient persons.
When obtained from sunlight (as opposed to diet and supplements), there is no toxic dose of vitamin D.
The American Cancer Society has not made an official recommendation regarding vitamin D supplements or exposure to sunlight.
Much of the evidence comes from observational studies. There are many variables involved, and a person spending considerable time outside may be benefiting from increased physical activity as well as exposure to the sun. More randomized, controlled studies are needed to confirm the cancer-preventive effects of vitamin D.
The skin cancer versus sun exposure controversy is a prickly one. In Australia, where pale-skinned people of Northern European descent are exposed to high levels of ultraviolet radiation, the rate of skin cancer is the highest in the world. The incidence of malignant melanoma, on the rise since the 1930s, has been stabilized in recent years by a “Slip, Slop, Slap” campaign – slip on a shirt, slop on some sun screen and slap on a wide-brimmed hat.
That is still good advice nearly anywhere ... but with recognition of the need for moderation. Spending 10 to 15 minutes in the sun several days a week is not sun worship and will barely give you a tan. It may give you the vitamin D your body needs for good health.
Rupp is information and assistance case manager with the Northern Oklahoma Development Authority Area Agency on Aging.
