WASHINGTON — Got milk? You may need a couple cups more than today’s food labels say to get enough vitamin D for strong bones.
But don’t go overboard: Long-awaited new dietary guidelines say there is no proof that megadoses prevent cancer or other ailments — sure to frustrate backers of the so-called sunshine vitamin.
The decision by the prestigious Institute of Medicine, the health arm of the National Academy of Sciences, could put some brakes on the nation’s vitamin D craze, warning that super-high levels could be risky.
“More is not necessarily better,” said Dr. Joann Manson of Harvard Medical School, who co-authored the Institute of Medicine’s report being released today.
Most people in the U.S. and Canada — from age 1 to age 70 — need to consume no more than 600 international units of vitamin D a day to maintain health, the report found.
People in their 70s and older need as much as 800 IUs. The report set those levels as the “recommended dietary allowance” for vitamin D.
That’s a bit higher than the target of 400 IUs set by today’s government-mandated food labels, and higher than 1997 recommendations by the Institute of Medicine that ranged from 200 to 600 IUs, depending on age.
But it’s far below the 2,000 IUs a day that some scientists recommend, pointing to studies that suggest people with low levels of vitamin D are at increased risk of certain cancers or heart disease.
“This is a stunning disappointment,” said Dr. Cedric Garland of the University of California, San Diego, who wasn’t part of the institute’s study and says the risk of colon cancer in particular could be slashed if people consumed enough vitamin D.
Vitamin D and calcium go hand in hand, and you need a lifetime of both to build and maintain strong bones. But the two-year study by the Institute of Medicine’s panel of experts concluded research into vitamin’s D possible roles in other diseases is conflicting. Some studies show no effect or even signs of harm.
As for calcium, the report recommended already accepted levels to go along with your daily D — about 1,000 milligrams of calcium a day for most adults, 700 to 1,000 mg for young children, and 1,300 mg for teenagers and menopausal women. Too much can cause kidney stones; the report said that risk increases once people pass 2,000 mg a day.
New guidelines for vitamin D
New recommendations from the Institute of Medicine say people ages 1 to 70 should get 600 IUs of vitamin D per day. People 70 and older should get 800 IUs.
A cup of D-fortified milk or orange juice has about 100 IUs. The best sources might be fatty fish — some servings of salmon can provide about a day’s supply. Other good sources are D-fortified cereals.
However, the average American already has enough vitamin D circulating in his or her blood. We make it from sun exposure, and many people take multivitamins or D-containing dietary supplements.
