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Vital Signs

Fall 2009

Getting Enough Vitamin D Essential to Maintain Overall Health


Getting Vitamin DVitamin D is essential for health, but an estimated 75 percent of the U.S. population has insufficient levels, raising the risk for a wide range of problems, including bone disease, infectious diseases and cardiovascular disease, UCLA experts say.

Vitamin D is produced in the skin by exposure to the sun’s ultraviolet rays. However, as more people stay indoors and wear sunscreen and protective clothing amid concerns about skin cancer, many are not getting the amount of sunlight they need for their skin to produce the nutrient. “But through short bursts of exposure, people can get enough sunlight to create vitamin D without putting themselves at risk for skin damage,” says John S. Adams, M.D., vice chair for research and director of UCLA’s Orthopaedic Hospital Research Center. He recommends exposing 10-15 percent of the body’s surface — not necessarily the face, arms or neck, which are the most prone to skin cancers — for 15 minutes at mid-day two to three times a week during the late spring, summer and early autumn.

Doctors have long known that vitamin D is important to bone health — insufficient levels in the body is a key contributor to osteoporosis, for example — but recent evidence indicates the vitamin’s importance in decreasing the risk for the nation’s leading killers. “Obesity, high blood pressure, insulin resistance and cardiovascular disease affect a huge portion of the U.S. population, and vitamin D insufficiency is associated with all of these conditions,” Dr. Adams says.

In addition to sunlight, vitamin D comes from the diet — most commonly through fortified cereals, milk and other dairy products; and fatty fishes such as wild-caught, but not farm-bred, salmon. But few people consume enough vitamin D through food. The problem is particularly acute among older adults, says UCLA geriatrician James Davis Jr., M.D. “Older people tend not to eat the same foods as when they were younger. They may not digest milk products as well, they may be concerned about cholesterol and fat, and fish can be expensive,” notes Dr. Davis.

For these patients — and, indeed, for most adults — oral supplements in combination with careful sunlight exposure are generally required to ensure sufficient vitamin D levels. For most people who are already vitamin D sufficient, the amount of vitamin D needed is approximately 800 to 1,000 international units (IU) a day from supplements and dietary sources. However, because most of us are already vitamin D insufficient, we routinely will need up to 500,000 to 1 million IU over the course of a month or so in the form of concentrated supplements to return to the normal range, Dr. Adams says.

Vitamin D levels are typically measured with a simple blood test, 25-hydroxyvitamin D. Because few people show symptoms of vitamin D insufficiency, the UCLA experts recommend that patients ask their doctors for the test, particularly as they get older.

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