Taking calcium supplements could raise the risk of heart damage, according to a new study by Johns Hopkins University. The research, which has been published in the Journal of the American Heart Association, also finds that a diet high in calcium-rich foods appears to be protective.
The researchers looked at 10 years of medical tests on more than 2,700 people in the Multi-Ethnic Study of Atherosclerosis. Although they caution that their work only documents an association between calcium supplements and atherosclerosis, they conclude that it ‘appears to be more beneficial to health to increase calcium intake from whole food than to supplement’.
Erin Michos, the study’s lead author, said: ‘When it comes to using vitamin and mineral supplements, particularly calcium supplements being taken for bone health, many Americans think that more is always better. But our study adds to the body of evidence that excess calcium in the form of supplements may harm the heart and vascular system.’
This was a prospective cohort study, looking at the natural history of the deposition of calcium on the walls of coronary arteries. These kinds of studies are ideal to establish the natural history of a disease or condition and are part of the overall determination of causality.
What was established in this study is that supplementation with higher levels of calcium is associated with coronary artery calcification, a known risk factor for subsequent ismchaemic heart disease leading to myocardial infarction ( heart attacks).
The total picture however was not so simple, with no such association being seen in people consuming comparably higher levels of calcium in their diets and not taking supplements.
This is important as traditional advice, particularly for women post menopause is to take calcium supplements, often involving the consumption of between 600-1200mg calcium from supplements alone in order to ensure and enhance bone strength; higher level evidence in the form of a recent RCT ( randomised control trial) and a meta analysis of randomised controlled trials (highest level of evidence) have however established that calcium supplements are associated with higher risks of heart disease and that they are not the benign entities once thought.
Take home message: it appears to be more beneficial to overall health to increase calcium intake from whole food than to supplement, however any decision to start or discontinue supplementation should be taken in conjunction with medical advice.