The Vitamin D dilemma


by By Sharon Salomon, MS, RD / myRegence Contributor

Posted on July 17, 2009 at 9:50 AM

Updated Wednesday, Oct 30 at 9:40 AM

Years ago, we slathered our skin with baby oil to maximize the sun's tanning power. It never occurred to us that it might be healthier to block out those rays. We thought that having a tan made us look healthy. When scientists found that rising skin cancer rates were associated with exposure to the sun, we replaced the baby oil with sunscreen.

But the sun provides more than a bronze tone to the skin. The ultraviolet rays, specifically UVB rays, set off a series of reactions in the skin that results in the production of vitamin D. That's why vitamin D is often called the "sunshine vitamin". However, when we use sunscreen, we shield ourselves from the hazards, as well as the benefits of ultraviolet rays. What's a health-conscious sun-worshipper to do?

Food sources for vitamin D are limited. They include cod liver oil (probably not a big source for most of us), fortified milk, fatty fish as well as eggs, liver, mushrooms and fortified cereals. Until recently, there wasn't much concern about deficiencies because it was believed that food, combined with sunshine, would result in adequate levels. Now that more people are heeding the warnings about skin cancer, there is concern about the potential for widespread vitamin D deficiency.

Some researchers are saying there is already an epidemic of vitamin D deficiency in the United States, though this claim is far from proven. According to Dr. Susan Van Dyke, a Paradise Valley, Ariz. dermatologist, most light-skinned American women between the ages of 19 and 49 have adequate levels of the vitamin. However, among those with darker skin, 12% show deficiencies because their epidermis is less efficient at producing the vitamin.

Health professionals don't yet agree about what constitutes sufficient levels of vitamin D in order to provide enough for the systems that use it-especially the ones that use vitamin D to prevent disease.

Vitamin D is involved in bone formation and helps the body use calcium, which is why it's added to milk. But recent research seems to indicate that vitamin D is way more important to our health than just building strong bones. Preliminary findings indicate that vitamin D is involved in immune function, proper insulin secretion and blood pressure regulation as well as balance and muscle coordination, prevention of colon, breast and prostate cancers and protection against autoimmune diseases like multiple sclerosis and rheumatoid arthritis. That's a pretty impressive list. Most of this, however, is based on observation among groups of people and not on actual scientific testing, so it's still in the theory stage.

Most practitioners agree on the ways to maximize vitamin D levels. Liz Friedrich, a dietitian and health promotion consultant, takes a conservative stance. She encourages people to perform outdoor activities without sunscreen for very short periods to ensure adequate production of vitamin D. She believes that many people are already getting enough vitamin D if they consume fortified dairy products, eat fish and engage in outdoor exercise. As for blood testing of vitamin D levels, Friedrich questions the validity of the tests.

"If you read up on the testing, you'll see there are many factors that affect blood levels of vitamin D&hellip even experts agree that the normal range has not been well defined." Friedrich says. "I take the tried and true route--eat a healthy diet, take a multivitamin mineral supplement and spend some time outdoors without sunscreen."

Dr. Van Dyke adds, "The evidence is strong that exposure to sun contributes to both melanoma and non melanoma skin cancers. One in three Americans will develop skin cancers; one in seventy will develop melanoma. Does it make sense to expose yourself to a known carcinogen like the sun?"

Van Dyke recommends that people eat foods containing vitamin D and use a multivitamin mineral supplement to ensure adequate intake. She says that exposure to "incidental or casual sun", like walking to and from the car, should be enough to provide some production of vitamin D by the skin. Van Dyke urges people to wear sunscreen all the time, and to apply it properly by following the instructions on the label. According to the Harvard School of Public Health, sunscreen takes a few minutes to have a vitamin D-dampening effect, so if you put it on just before you go outside, you can get enough exposure during the first few minutes in the sun to get some vitamin D.

The bottom line: vitamin D is important for good health, so be sure to eat foods containing it every day. If you're concerned that you're not getting enough from food, talk to your doctor about taking a multivitamin mineral supplement with vitamin D3, and find out if you need a blood test. If your levels are low, you may need a higher dose.

As for the sun, be prudent. Occasional exposure for short periods (up to 15 minutes of sunshine, three times a week) can maximize production of vitamin D, but be sure to wear sunscreen when you spend long periods outdoors.

About the Author
Sharon Salomon, M.S., R.D., is a registered dietitian, freelance writer and dedicated eater with professional culinary training. Her articles have appeared in Today's Dietitian, Edible Phoenix, Sweat Magazine as well as many other food and nutrition publications and websites. Sharon works diligently to meet the challenge of balancing the calories she consumes in the interest of pleasure and research with sufficient exercise to keep her weight stable.