According to the Institute of Medicine nearly 70% of older American women are taking calcium supple- ments hoping to cut their risk of osteoporotic fractures. Most data suggests taking calcium supplements reduce the risk of fractures only slightly. The safety of calcium supplements for women has been largely taken for granted. However, data linking the use of calcium supplements with calcification of arteries and an increased risk of heart attack and stroke continues to mount.
Last fall we discussed a meta-analysis of 15 randomized controlled trials by Dr. Reid and associates which showed about a 30% sig- nificant increased risk of having a heart attack in those taking calcium supplements compared to those taking a placebo. These researchers excluded data from women also taking vitamin D as there is some evidence vitamin D supplements may reduce CVD events. This same research group analyzed patient data from the Women’s Health Initiative Calcium/Vitamin D supplementation study. They calculated the risk of CVD events in the 16,718 subjects who were not taking personal calcium supplements at the start of the study. In these women those assigned to start taking calcium and vitamin D supplements they found about a 20% increased risk of CVD events over the next 7 years. They also analyzed data from several other placebo controlled trials in which subjects were given either calcium supplements either with or without vitamin D. Combining data from all 8 clinical trials with 28,072 subjects randomly assigned to a placebo or calcium (with or without vitamin D) Dr. Bolland observed there was a 24% increased risk of heart attack and about a 15% increased risk of stroke in those who started taking calcium supplements. Data from this analysis showed that for every 4000 subjects taking calcium supplements for 5 years there would only be only 3 fewer fractures and at least 6 more heart attacks as well as more strokes and other CVD events. The risk for most people appears to outweigh the modest benefit.
Bottom Line: It now appears that for most women and the vast majority of men that whatever modest benefit there may be from taking calcium supplements on bone health those benefits are likely outweighed by an even greater increased risk of CVD. Vitamin D supplements in those with low serum 25-OH levels (<30ng/dl) make sense but won’t prevent the adverse effects of calcium supplements.
By James J. Kenney, PhD, RD, FACN
1. BMJ 2010;341:c3691doi:101136.c3691
2. BMJ 2011342:d2040doi:10.1136/bmjd2040
Stephanie Ronco has been editing for Food and Health Communications since 2011. She graduated from Colorado College magna cum laude with distinction in Comparative Literature. She was elected a member of Phi Beta Kappa in 2008.