Tuesday, January 20, 2004

Warnings about vitamin D deficiency ring out every winter, when levels of the strong-bones nutrient drop to rock-bottom levels among people in northern areas of the world.

Concerns are taking on a higher profile this year.

New studies are hinting that vitamin D may play a bigger role in keeping people healthy than once thought. They have linked vitamin D deficiency to an increased risk of other diseases, including some cancers, high blood pressure and rheumatoid arthritis in older women.

The National Institutes of Health, which convened a conference of vitamin D experts in October, is considering changes in health policy to prevent the deficiency.

Humans make vitamin D in their skin, and ultraviolet rays from the sun change it into an active form that the body can use. Vitamin D helps the intestines absorb calcium from food and regulates the amount of calcium and phosphorus in bones.

Among those suggestions by the experts: Advising people to consume more vitamin D, adding vitamin D to more foods and suggesting that people get 15 minutes of sunlight three times a week without sunscreen.

About one in three people don't get enough vitamin D. The problem is more serious in the winter when people stay indoors and sunlight is weak; among older people, whose skins don't make as much vitamin D; and in people with dark skin that blocks passage of sunlight.

Without enough vitamin D, it doesn't matter how much milk, yogurt, spinach and other calcium-rich food a person eats. The body will have a tough time absorbing it, leaving older people vulnerable to osteoporosis and children to rickets.

Osteoporosis is a leading cause of hip and other bone fractures in older people.

Rickets, which causes bones to soften and bend, is making a comeback in the United States.

NIH attributes the comeback to use of milk substitutes like soy that lack certain nutrients; failure to give vitamin D supplements to breast milk-fed babies; and lack of childhood exposure to sunlight.

Current guidelines advise 200 International Units daily for people under age 50, 400 IUs for those 50-70 and 600 IUs for older people.

Some experts think adults should get 1,000 IUs a day. Vitamin D builds up in the body, and can become toxic. That's why 2,000 IUs per day is the maximum safe intake.

A typical multivitamin has 200 to 400 IU, and an 8-ounce glass of milk or fortified orange juice has about 100 IUs, and a tablespoon of cod liver oil 1,360 IUs. Salmon, herring and sardines are other good sources.

Make an extra effort to get enough vitamin D this winter and the rest of the year.