The nation’s top scientific advisory panel today recommended that most children and adults modestly increase their intake of vitamin D, known as the “sunshine vitamin,” from a daily dietary intake of 200 international units to 600 international units. The panel also extended the safe upper limit for older children and adults from 2000 IU to 4000 IU daily.
The Institute of Medicine (IOM) released its report November 30, 2010, after two years of study and debate. The IOM had not changed its dietary guidelines for vitamin D since 1997.
During the last 13 years, though, some studies had suggested that much higher doses of vitamin D could prevent a variety of illnesses, from bone diseases to strokes and cancer. But the IOM panel was more cautious, and said that although more vitamin D is beneficial to bone health, studies related to other conditions were inconsistent and inconclusive. Furthermore, the panel said taking mega doses over a long period of time might harm some people.
The IOM recommended:
- Everyone ages 1 to 70 should take 600 IU daily.
- Adults older than 70 should take 800 IU daily to optimize bone health.
- The safe upper limit for infants up to 6 months is 1000 IU daily.
- The safe upper limit for infants 6 to 12 months is 1500 IU daily.
- The safe upper limit for children 1 to 3 years old is 2500 IU daily.
- The safe upper limit for children 4 to 8 years old is 3000 IU daily.
- The safe upper limit for everyone older than 8 is 4000 IU daily.
Kevin Fiscella, M.D., a University of Rochester Medical Center family physician who studies health disparities, noted that African Americans often have lower serum vitamin D levels than whites.
He published an observational study earlier this year suggesting a link between D deficiency and a higher number of heart and stroke-related deaths among blacks compared to whites. A second study showed that a lack of vitamin D among blacks may also explain a higher death rate in colon cancer among blacks compared to whites. A third URMC study suggested a link between lower vitamin D levels among black women and more aggressive breast cancer.
“While most U.S. adults may achieve reasonable blood levels of vitamin D through diet and sun light, national data show that persons with darker skin, particularly African Americans, commonly have D levels believed to be suboptimal,” Fiscella said. “This is particularly true among those who are lactose intolerant and avoid vitamin D fortified milk products. Research is sorely needed among this group to firmly establish optimal levels.”
The IOM report will resonate differently with various health providers and patients, Fiscella added. Physicians will most likely be a bit more conservative in terms of testing for vitamin D deficiencies and prescribing supplements, he said.
“My own view is that this is an area of great uncertainty and it is ripe for research,” Fiscella said. “We have reasonable observational data suggesting that vitamin D can be of benefit in the prevention of some cancers, insulin resistance, and vascular conditions. But we’ve been here before with other nutrients, where promising observational data was not born out by subsequent clinical trials.”
Until we have stronger evidence one way or another, Fiscella said, physicians should be honest with patients about the current state of evidence and help them to make an informed decision on use of vitamin D supplements.
The IOM found that the majority of Americans are getting sufficient vitamin D, which can be consumed through fortified dairy foods, orange juice, fatty fish, and D-containing dietary supplements, or produced by the skin during sun exposure.
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