There is growing evidence that the risk of cardiovascular events in older women, especially heart attacks, are increased by calcium supplements. Postmenopausal or older women are commonly prescribed calcium supplements to maintain bone health. They are often combined with vitamin D supplements, but it’s still not clear if the supplementation of calcium, with or without vitamin D, could have an impact on the heart.
A 7 year study of more than 36,000 women revealed no cardiovascular effect of a vitamin D and calcium supplement combination, but most individuals were already supplementing with calcium, which might have resulted in any adverse effects being obscured. So researchers re-analyzed the results of the study to provide a better estimation of the how calcium supplements, with or without vitamin D, impacts the risk of cardiovascular events.
Data from 16,718 women who weren’t taking personal calcium supplements at the beginning of the study was analysed and it was revealed that those allocated to a vitamin D and calcium supplement combination had an increased cardiovascular event risk, particularly heart attack.
In comparison, a vitamin D and calcium supplement combination didn’t change cardiovascular risk for women who were supplementing with calcium at the beginning of the study.
The researchers suspect that the sudden change in blood calcium levels after taking a supplement brings about the adverse effect, instead of it being related to the total amount of calcium taken. High blood calcium levels are associated with hardening of the arteries, which could also help to explain these results.
Additional data from 13 other studies, involving 29,000 individuals in total, also revealed consistent increases in stroke and heart attack risk associated with calcium supplementation, with or without vitamin D.