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A long-awaited report from the Institute of Medicine to be released Tuesday triples the recommended amount of vitamin D most Americans should take every day to 600 international units from 200 IUs set in 1997.
That's far lower than many doctors and major medical groups have been advocating -- and it could dampen some of the enthusiasm that's been building for the sunshine vitamin in recent years.
Many doctors have added blood tests of vitamin D levels to annual physicals, and sales of vitamin D supplements have soared to $425 million last year from $40 million in 2001, according to the Nutrition Business Journal.
It's long been known that vitamin D is essential to maintaining strong bones. But hundreds of new studies have also linked low vitamin D levels to a higher risk of a slew of chronic health problems -- heart disease, stroke, diabetes, prostate, breast and colon cancers, auto-immune diseases, infections, depression and cognitive decline. Studies have also suggested that many Americans are vitamin D deficient due to working and playing indoors and slathering on sunscreen.
The Institute of Medicine, an arm of the National Academy of Sciences that sets governmental nutrient levels, said there wasn't enough evidence to prove that low vitamin D causes such chronic diseases; it based its new recommendations on the levels needed to maintain strong bones alone.
'The evidence for bone health is compelling, consistent and gives strong evidence of cause and effect,' said Patsy Brannon, a professor of nutritional sciences at Cornell University and member of the IOM panel. For the other health problems, she said, 'there are relatively few randomized controlled trials, and even in the observational studies, the effects are inconsistent.'
The new recommendations, which cover the U.S. and Canada, call for 600 IUs daily for infants through adults age 70 and 800 IUs after age 71. The IOM assumed that most people are getting minimal sun exposure, given rising concern over skin cancer and latitudes where the sun is too weak to create vitamin D on the skin much of the year. The panel also raised the acceptable upper limit of daily intake to 4,000 IUs for adults, from 2,000 previously.
Those levels do take into account vitamin D from food sources -- but only a few, such as salmon and mackerel, contain much naturally. Milk fortified with vitamin D contains about 40 IUs per cup. Most Americans and Canadians need to get much of their vitamin D from supplements.
The IOM panel also issued new recommendations for daily calcium intake -- ranging from 700 milligrams for children aged 1 to 3 up to 1,200 milligrams for women 51 and older. The main change from the 1997 recommendations was to lower the recommended level for men 50 to 70 to 1,000 from 1,200. The panel noted that teenage girls may not get enough calcium, and that postmenopausal women may get too much, running the risk of kidney stones. 2010-12-20
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