The new IOM’s Report on the Dietary Reference Intakes for calcium were also part of the same report on vitamin D. IOM’s experts did not alter their previous RDA and UL guidelines for calcium intake. The Food and Nutrition Board focused primarily on bone health in establishing the calcium RDAs and ULs. The IOM’s expert panel did note that except for teenage girls who mostly get too little calcium that many older women may be taking calcium supplements large enough to increase the risk of kidney stones.
It appears to this reviewer the IOM’s panel may not have been concerned enough about emerging evidence linking high calcium intake primarily from supplements with more heart attacks and possibly other adverse cardiovascular disease (CVD) events. Dr. Bolland at the University of Auckland in New Zealand published a me- ta-analysis of 15 calcium supplement trials with more than 12,000 middle-aged and older people. These placebo-controlled clinical trials were primarily focused on reducing bone fractures in older women. Dr. Bolland reported that there was about a 30% increased risk of having a heart attack in those taking the calcium supplements compared to the placebo perhaps by increasing blood clotting and/or promoting calcification and stiffening of arteries.1 Dr. Bolland did not look at studies that combined vitamin D with calcium supplements to reduce bone fractures because there is evidence that extra vitamin D may reduce CVD risk. Another systemic review found that higher doses of vitamin D may actually reduce CVD risk but failed to find a link between increased calcium supplement use and more heart attacks.2
The IOM’s report on calcium and vitamin D paid no attention to the role excessive salt intake plays in promoting both kidney stones and osteoporosis via increasing calcium loss in the urine. Excessive salt intake also greatly increases the risk of stiffened arteries and increases intracellular calcium. Indeed, if Ameri- cans reduced their salt intake to less than 1500mg/day it is likely that the RDA for calcium could be reduced to a level that would be less likely to promote kidney stones and possibly CVD in older Americans.
By James J. Kenney, PhD, RD, FACN
1. Br Med J 2010;341:c3691 2. Ann Intern Med 2010;153:315-23
Stephanie Ronco has been editing for Food and Health Communications since 2011. She graduated from Colorado College magna cum laude with distinction in Comparative Literature. She was elected a member of Phi Beta Kappa in 2008.