The adult recommended dietary allowances (RDAs) for calcium have changed several times over the last half-century, and controversy continues about how much calcium healthy adults need and whether the nutrient is delivered effectively by supplements rather than calcium-rich foods.
[Photo: Dr. John Anderson]
An article co-authored by Dr. John Anderson, adjunct professor of nutrition at University of North Carolina Gillings School of Global Public Health, examines recent research that questions whether adults need more than 700 to 800 mg of calcium per day to support bone health. That newer research also suggests that calcium supplements may not help older adults reduce fractures or maintain bone mass and that, in fact, supplements may contribute to dangerous calcifications in the arteries, heart, kidneys, and brain.
About 60 percent of women in middle and older age in the U.S. take calcium supplements. The figure is higher – 74 percent – according to a study of women in Sweden. Heart attacks, strokes and other cardiovascular diseases were much more common in these studies among women whose supplemental calcium intake was between 600 mg. and 1400 mg. per day, and higher.
Calcium intakes greater than 1000 mg. per day, as recommended by the Institute of Medicine for the prevention of fractures in postmenopausal women, did not appear to be effective. Rather, bone resorption inhibitor drugs were determined to be the preferred therapy for low bone density.
Bone resorption is the process by which bone is broken down, resulting in a transfer of calcium from bone fluid to the blood.
In conclusion, Dr. Anderson’s review of recent research found that 700 mg. to 800 mg. of calcium per day is sufficient to maintain bone density and prevent hip and other fractures in both men and women – and that more than 1,000 mg. per day can be detrimental.
“Additional trials are needed to establish the impact that excessive calcium intake from supplements may have upon arterial calcification,” Dr. Anderson said. “In the interim, we strongly urge that the calcium needs of healthy, non-institutionalized adults be met primarily through calcium-rich and low-fat foods.”
The article, “Reassessment of Adult Recommendations and Supplements of Calcium,” appears in the January/February issue of Nutrition Today (abstract only available online). Dr. Anderson’s co-author, Dr. Clifford J. Rosen, of the Maine Medical Center Research Institute in Scarborough, was a member of the 2011 National Academy of Sciences (NAS) committee that published the NAS guideline, Dietary Reference Intakes: Calcium and Vitamin D.