I received several questions this week about an article published in the British Medical Journal suggesting that calcium supplements increase the risk of heart attacks. While I am not impressed by the techniques used by the authors to evaluate the risk of heart attacks in people taking calcium supplements, I believe that their conclusion has merit.

This is not the first study to demonstrate an increased heart attack risk in people taking calcium supplements. A randomized trial conducted in New Zealand over a five year period was reported in the British Medical Journal in 2008. It showed a greater number of heart attacks in elderly women taking calcium supplements compared to a group that was not taking calcium.

Several points need to be addressed. First, the risk is only apparent when calcium alone is supplemented. It has not been found when combinations of calcium and vitamin D have been taken, nor has it been found in when combinations of calcium and magnesium have been supplemented. Second, the risk has only been observed in women. It has not been demonstrated in men. Third, it is known that elevations of blood calcium in disease states are associated with an increased heart attack risk.

There is a known mechanism by which calcium supplementation could trigger heart attacks. Calcium causes muscles to contract. Calcium channel blocking medications counter the action of calcium in narrowing arteries and are therefore prescribed for people with angina (pain due to narrowed coronary arteries).

Magnesium is needed to allow muscles to relax. Magnesium supplementation is an alternative to the use of calcium channel blocking medications. When calcium alone is supplemented there is an increased likelihood that a spasm will occur in an artery supplying blood to the heart causing a heart attack. Since women tend to have smaller vessel diameters than men they are more likely to experience a heart attack with arterial spasm. This would explain why heart attack risk is increased in women taking stand-alone calcium supplements while the same result is not seen in men.

I am not a proponent of single nutrient supplementation. The body is designed to utilize well over 100 nutrients for ongoing maintenance and repair tasks. When one nutrient is supplemented to the exclusion of others bad things can and do happen.