Research Summary: The Effects of 3 Years of Calcium Supplementation on Common Carotid Artery Intimal Medial Thickness and Carotid Atherosclerosis in Older Women: An Ancillary Study of the CAIFOS Randomized Controlled Trial.
The benefits of calcium for bone health, especially among women, are well known. But recently, a number of studies have raised the issue of whether calcium supplementation increases the risk of heart disease. Is this a case of “robbing Peter to pay Paul” or are these fears unfounded?
The two sides of this argument appear to be evenly weighed. A 2010 British Medical Journal study concluded that calcium supplements "are associated with an increased risk of myocardial infarction [heart attacks]" while in the same year a meta-analysis showed "no significant relationship between supplementation and cardiovascular events." To lay this issue to rest, in the October 17, 2013 issue of the New England Journal of Medicine, a UC San Francisco researcher bypassed this thorny issue entirely by recommending that people get calcium from their diets, rather than supplements.
The most recent contribution to this ongoing debate was a study conducted at the University of Western Australia by Joshua R. Lewis et al. The research, published on Oct 23, 2013 in the Journal of Bone and Mineral Research, examined calcium intake among 1,460 elderly women in a randomized controlled trial over a 5-year period. One group was given a daily calcium supplement of 1.2g of elemental calcium in the form of calcium carbonate, and the other was given placebo. Carotid artery thickness and carotid atherosclerosis were measured in the 3rd year.
The researchers found that the women who took calcium, as opposed to the placebo, did not have increased carotid atherosclerosis. A total of 46.7% of the women who received calcium were found to have carotid artery atherosclerosis, compared with 54.7% of the women in the placebo group. Moreover, women in the highest third of total calcium intake (diet and supplements) had reduced carotid atherosclerosis, compared to participants in the lowest third. The researchers concluded that “these findings do not support the hypothesis that calcium supplementation increases carotid artery intimal medial thickness or carotid atherosclerosis, and high calcium intake may reduce this surrogate cardiovascular risk factor.”
Citation: Lewis JR, Zhu K, Thompson PL, Prince RL.The Effects of 3 Years of Calcium Supplementation on Common Carotid Artery Intimal Medial Thickness and Carotid Atherosclerosis in Older Women: An Ancillary Study of the CAIFOS Randomized Controlled Trial.J Bone Miner Res. 2013 Oct 23. doi: 10.1002/jbmr.2117. [Epub ahead of print]