Monday, October 21, 2013

Calcium Supplements and Cardiovascular Risk

As many of you know, I attended this year's Annual Meeting of the American Society for Bone and Mineral Research in Baltimore (October 4 - 7). While there, I sat in on some fascinating presentations on bone and muscle research--two of them, I thought may be of particularly interesting to you. 

In 2008, a study by Bolland et al. reported a possible association between calcium supplementation and cardiovascular risk. According to Bolland et al. in a 2010 follow-up study, "Calcium supplements (without coadministered vitamin D) are associated with an increased risk of myocardial infarction" The authors further concluded "A reassessment of the role of calcium supplements in the management of osteoporosis is warranted."

Since Bolland's two studies hit the press in 2008 and 2010, there has been considerable controversy over the safety of calcium supplementation as it relates to cardiovascular health. As a result, many people with osteoporosis have, unfortunately, reduced their calcium intake to sub-optimal levels. The two research presentations in Baltimore helped explain our current understanding of this important subject.

The first presentation was by Dr. Douglas Bauer, MD, from the University of California, San Francisco. Dr. Bauer's study assessed calcium intake and the incidence of death in 5967 men over the age of 65 years. The participant's dietary intake of calcium was 1142 ± 590 mg/day, and 65% used calcium supplements. The participants were followed over a 10-year period and those who took in more than 1565 mg/day of calcium had lower mortality than those who took in less than 621 mg/day. The highest rate of death from heart disease was seen in those with the lowest calcium intake (less than 621 mg/day). The authors concluded there was "no evidence that supplements increased the risk of mortality among those with the highest dietary calcium intake." And, "total calcium intake, use of calcium supplements and the combination of high dietary calcium intake and supplement use were not associated with total or cardiovascular mortality."

In the second presentation, Dr. Joshua Lewis, MD, PhD, from the University of Western Australia, Perth, reported on his analysis of 19 randomized controlled trials that studied women over the age of 50 who took calcium supplements. The study encompassed 59,844 participants. The authors concluded "data from this meta-analysis does not support the concept that calcium supplementation with or without vitamin D increase the risk of ischemic heart disease or total mortality in elderly women."  

I hope that the results of these new studies help reduce fears over calcium supplementation. Although these studies conclude that calcium supplementation, even without vitamin D, is not harmful, I still encourage you to maintain optimal vitamin D levels as well as an adequate intake of vitamin K, magnesium, and trace minerals. Vitamins and minerals work synergistically, and to flood the body with calcium without important utilizing factors has the potential to cause metabolic imbalance. So please, I hope you will all continue to take your calcium!

Bolland M.J., P.A. Barber, R.N. Doughty, et al. 2008. Vascular events in healthy older women receiving calcium supplementation: randomized controlled trial. BMJ Feb 2;336(7638):262-6.

Bolland M.J., A. Avenell, J.A. Baron, et al. 2010. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta analysis. BMJ 341:c3691.

Bauer D., S. Harrison, P. Cawthon, et al. 2013. Dietary and supplemental calcium intake and the risk of mortality in older men: the MrOS Study. 35th Annual Meeting of the ASBMR. Abstracts, 1001, pS1.

Lewis J., L. Rejnmark, K. Ivey, et al. 2013. The cardiovascular safety of calcium supplements with or without vitamin D in elderly women: A collaborative meta-analysis of published and unpublished trial level evidence from randomized controlled trials. 35th Annual Meeting of the ASBMR. Abstracts, 1002, p S1. 
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