Neither higher levels of vitamin D sometimes recommended by doctors and testing laboratories nor calcium supplements are necessary for bone health for most Americans, according to a recent report from the Institute of Medicine (IOM).
Calcium and vitamin D are two essential nutrients long known for their role in bone health. More recently, some studies have suggested that vitamin D offers protection against chronic autoimmune diseases and some cancers. Over the last ten years, the public has heard conflicting messages about other benefits of these nutrients—especially vitamin D—and also about how much calcium and vitamin D they need to be healthy.
To help clarify this issue, the US and Canadian governments asked the IOM, a nonprofit health advisory group, to assess current research on calcium and vitamin D's effects on health. A committee of experts reviewed the evidence and updated the Dietary Reference Intakes (DRIs), which government agencies use to ensure that nutrition label information is accurate and health professionals use when counseling patients about diet. The IOM committee considered more than 1,000 studies on health outcomes associated with vitamin D and calcium and confirmed that they play an important role in bone health, but that there is not convincing evidence of their role in other health conditions, and felt that more research was needed before making any recommendations outside of those related to bone health.
The committee found that the majority of Americans and Canadians are receiving adequate amounts of both calcium and vitamin D. They concluded that a level of vitamin D (measured as 25-hydroxyvitamin D or 25OHD) in the blood of greater than 20 ng/mL will sufficiently maintain bone health for most people. Many laboratories and physicians currently recommend that 25OHD levels be greater than 30 ng/mL, but the IOM report found no evidence that levels needed to be that high, while they found that 25OHD levels over 50 ng/mL could be dangerous. Six hundred international units (IUs) of vitamin D daily meets the needs of almost everyone in the United States and Canada, although people 71 years of age and older may require as much as 800 IUs per day because of potential physical and behavioral changes related to aging, the report says.
IOM maintains that 700 milligrams (mg) of calcium a day meets the needs of almost all children ages 1 through 3, and 1,000 mg daily is appropriate for almost all children ages 4 through 8. Adolescents ages 9 through 18 require no more than 1,300 mg per day. For most adults ages 19 through 50, and for men until age 71, 1,000 mg covers daily calcium needs. Women starting at age 51 and both men and women age 71 and older need no more than 1,200 mg per day, the report says.
The only group that gets too little calcium is adolescent girls ages 9 through 18. In contrast, older women often take too much and put themselves at risk for kidney stones. Some studies show that excess calcium can increase risk for heart disease, the report adds.
Previous estimates of vitamin D deficiency in North America were too high because laboratories measuring vitamin D levels in the blood were not using standardized measurements of sufficiency and deficiency, known as cutpoints, the committee maintained.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Press release. IOM Report Sets New Dietary Intake Levels for Calcium and Vitamin D To Maintain Health and Avoid Risks Associated With Excess. Institute of Medicine. Available online at http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=13050 through http://www8.nationalacademies.org. Issued November 30, 2010. Accessed December 14, 2010.
Gina Kolkata. Report Questions Need for 2 Diet Supplements. New York Times. Available online at http://www.nytimes.com/2010/11/30/health/30vitamin.html through http://www.nytimes.com. Published November 29, 2010. Accessed December 14, 2010.
Report at a Glance. DRIs for Calcium and Vitamin D. Institute of Medicine. Available online at http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/DRI-Values.aspx through http://www.iom.edu. Published November 30, 2010. Accessed December 14, 2010.