A study of 1,471 post menopausal women in New Zealand with a mean age of 74 were randomized to receive 1 gm of calcium citrate or placebo daily for 5 years. The occurrence of sudden death, heart attacks, stroke and transient ischemic attacks were reported by either the women or their family members. A twofold increase in MIs was seen among women in the calcium group compared with the placebo group. When accumulating the total of heart attacks, strokes or sudden deaths, the incidence was 1.47 times higher in the calcium group than in the placebo group as well. However, when the investigators incorporated national health database results for unreported cardiovascular events, the increase in the incidence in heart attacks was not statistically significant.
Bolland M, Barber P, Doughty R, et al. Vascular events in healthy older women receiving calcium supplementation: Randomised controlled trial. BMJ 2008;Feb 2; 336:262-266
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Commentary: It is interesting and important to point out that the Womenâ€™s Health Initiative ( Circulation 2007;115:846) showed no statistically significant increase in cardiovascular events in postmenopausal women receiving calcium supplements and another study showed a non-significant but yet a trend in increased risk for ischemic heart disease. (Arch Intern Med 2006;166:869). These three studies all point to the fact that there is no definite statement or conclusion that can be made regarding calcium and cardiovascular events. That said, I am concerned that the importance of calcium supplementation in postmenopausal women, especially younger postmenopausal women, is very overplayed. And, most individuals do not estimate their dietary calcium sources, and then use a pill to supplement in addition to dietary sources to meet a total of 1,200mg-1,500 mg per day. Rather, they often take 1,000 mg to 1,500 mg per day, in addition to their dietary sources. A result of this misinterpretation of calcium guidelines might be excessive calcium and depletion of other nutrients such as copper, silicon and magnesium, all of which have cardioprotective benefits. In addition, these total daily calcium guidelines turn out to be most important to young girls and postmenopausal women 65 and older. These are the times in life when lack of bone architecture/density growth (young girls) and bone loss (elderly women) is most crucial in the prevention of osteoporosis and risk for fractures. For women in their 30â€™s, 40â€™s, 50â€™s and early 60â€™s, our bones seem to do just fine with average dietary intake.