Calcium/CVD Risk Debate Gets New Fodder From Analysis

April 11, 2014

SEVILLE, SPAIN — Calcium supplementation with and without vitamin D does not increase the risk of coronary heart disease or all-cause mortality in elderly women, a new meta-analysis has shown[1].

Presented by Dr Joshua Lewis (University of Western Australia, Perth) here at the World Congress on Osteoporosis, Osteoarthritis, and Musculoskeletal Disease, the Australian researchers observed no relationship between calcium supplementation with and without vitamin D and coronary heart disease risk in 18 clinical reports with data from more than 63 500 elderly women.

The findings contradict a 2010 meta-analysis in BMJ that reported calcium supplementation (without coadministered vitamin D) was associated with a significantly increased risk of MI in 8151 men and women. In that meta-analysis, calcium supplementation was associated with a relative 31% increased risk of MI. A similar meta-analysis that included trials with vitamin-D coadministration found similar results.

"Calcium and vitamin D are essential for bone health, and supplements are widely used in the elderly who cannot meet their recommended daily intake through the diet alone," Lewis told heartwire . "Until recently, there were thought to be relatively few serious adverse effects of these supplements."

The 2010 studies were controversial, particularly since the Institute of Medicine recommends a calcium intake of 1000 mg daily for women in early and middle adulthood until age 50 and 1200 mg daily for women after age 50. The BMJ findings were criticized for including clinical trials that relied on self-reported events, including significantly more men in the calcium-supplemented groups, a failure to adjust for confounding risk factors, and a lack of a plausible biological mechanism.

"We therefore are firmly of the opinion that this remains an important, however yet-unproven, hypothesis that needs to be explored more fully," said Lewis. He added that the group focused the analysis on women, as the overwhelming majority of individuals included in clinical trials are female.

In their review of 63 564 women taking calcium supplements with and without vitamin D, there were 3390 CHD events and 4157 deaths from any cause. All events were verified by clinical review, hospital records, or death certificate. For the five trials that focused on coronary heart disease events, the pooled relative risk for those taking calcium supplements was 1.02. Among the 17 trials with all-cause-mortality data, the pooled relative risk was 0.96. Neither was statistically significant.

Despite the findings, Lewis said he would like to see a large-scale randomized clinical trial with calcium and vitamin-D supplementation in order to fully assess bone and vascular outcomes. Doing so would help "determine the risk/benefit profile of these commonly used supplements," he said. In terms of current recommendations, Lewis said women, especially women at a higher risk of osteoporosis who can't meet their daily recommended requirements of calcium (1300 mg/day) with diet or hydroxyvitamin D (>50 nmol/L) through sunshine and diet, can continue to supplement with 500 to 600 mg of calcium and 800 to 1000 IU of vitamin D.

The research was supported by a Raine Medical Research Foundation grant. The authors have no disclosures to declare.

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