According to findings published in the American Journal of Clinical Nutrition, daily supplements of calcium plus vitamin D for seven years were associated with a 17 percent increase in the risk of urinary tract stones, compared with placebo.
The data was obtained from the Women’s Health Initiative (WHI) randomized clinical trial, which involved 36,282 postmenopausal women receiving either placebo or 400 international units of vitamin D and 1,000 milligrams of calcium carbonate per day.
Risks versus benefits
Commenting on the study’s findings Harry Rice, PhD, director of regulatory & scientific affairs for the United Natural Products Alliance (UNPA), a trade association for dietary supplement and functional food manufacturers, said that the WHI has provided from important knowledge from a scientific perspective.
However, the initiative has also led to a number of “mixed messages being communicated to the public […] not to mention cynicism about what is considered trusted information.
Dr Rice said the new analysis about urinary tract stone formation will most likely confuse the public as they balance the benefits of vitamin D and calcium with the potential risk of urinary tract stones.
“Should the finding that supplementation with calcium and vitamin D is associated with an increase in the number of urinary tract stones change public health policy? Absolutely not!” said Dr Rice.
“Without debating the methodology used to draw the present conclusion, consider whether or not the risk (i.e. increased likelihood of urinary stone formation) of taking supplements of calcium and vitamin D outweighs the benefit of preventing hip fractures.
“In 2006, following the New England Journal of Medicine publication ‘Calcium plus vitamin D supplementation and the risk of fractures’, NIH’s press release was very clear that ‘…the public health benefit of the supplements outweighs the risks [kidney stones]’.
“That message was true in 2006 and publication of the present analysis shouldn’t change that advice,” added Dr Rice.
Study details
Led by Robert Wallace, MS, MD, from the University of Iowa, the researchers analyzed data from 18,176 women receiving the vitamin D-calcium combination and 18,106 women receiving placebo for an average of seven years.
At the end of the study period, the researchers reported that calcium plus vitamin D supplements were associated with a 17 percent increase in the incidence of urinary tract stones.
Source: American Journal of Clinical Nutrition
July 2011, Volume 94, Number 1, Pages 270-277, doi: 10.3945/ajcn.110.003350
“Urinary tract stone occurrence in the Women's Health Initiative (WHI) randomized clinical trial of calcium and vitamin D supplements”
Authors: R.B. Wallace, J. Wactawski-Wende, M.J. O'Sullivan, J.C. Larson, B. Cochrane, M. Gass, K. Masaki