Sunny Outlook

Vitamin D, the sunshine vitamin, is one of the nutrition world’s bright lights.

May 2014

by Lisa James


Among the class of nutrients known as vitamins, the one labeled D is unique: It’s the only vitamin that can be synthesized in skin exposed to sunlight.

You would think, since we can create our own vitamin D, that everyone has a plentiful supply. But our indoor, sedentary lives, along with understandable concerns about the link between excessive sun exposure and skin cancer, means that many people’s vitamin D levels are inadequate. And given all the roles vitamin D plays in the body, that places the health of millions at risk.

Not Enough D

Evidence suggests that low vitamin D is widespread. A 2011 Nutrition Research study found an overall US deficiency rate of more than 41%. Rates among African Americans and Latinos, whose darker skins are less efficient at converting sunlight to D, were considerably higher. Another study, this one in the British Journal of Nutrition, found that more than a third of the entire world’s population may suffer from low vitamin D.

More time spent indoors in front of screens is also a factor in suboptimal vitamin D levels. Window glass filters ultraviolet rays, responsible for D production in the skin, and fluorescent lights produce minimal amounts. What’s more, many people don’t get enough vitamin D in their diets.

Good All Over

The prevalence of vitamin D deficiency is especially troubling in light of studies showing how much the body depends on this crucial nutrient. A study published last month in the British Medical Journal linked low vitamin D levels to increased risk of death from cancer, cardiovascular disease and other disorders, and found that supplementation “significantly reduces overall mortality among older adults.” At the other end of the age spectrum, low vitamin D levels have been linked with an increased risk of anemia in children (Journal of Pediatrics 1/14).

Vitamin D enhances the immune system’s ability to fight infection and regulate inflammation. This may explain why people with lupus, a disease in which the immune system attacks the body itself, who took supplemental D experienced no flareups during the study period (Arthritis Research and Therapy 10/17/12). In addition, high vitamin D levels have been linked to lower colorectal cancer risk and better breast cancer survival (American Journal of Epidemiology 2/1/12, Anticancer Research 3/14).

The brain requires adequate vitamin D. Animal studies have linked low levels during pregnancy with poor brain function in offspring, and this vitamin may help control the kind of inflammation found in Alzheimer’s disease. Vitamin D may also help fight Parkinson’s disease and depression as well as multiple sclerosis, a disorder in which nerve cells lose their protective covering.

Vitamin D3, the form that has been found to be most helpful in maintaining adequate levels over the winter in at least one study, is often combined with nutrients that complement its effects. These include vitamin A, crucial to immune function, as well as calcium, vitamin K2 and other nutrients needed to keep bones healthy. Vitamin D is also a good match for resveratrol, a phytonutrient that, like D, has shown an ability to fight inflammation while protecting the brain and heart.

As you (safely) enjoy time in the sun this summer, remember you may still fall short on the sunshine vitamin. Be sure your body has all the vitamin D it needs.

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