#calcium supplements: can they increase heart attack risk in older women?

Research Suggests Calcium Supplements May Increase Heart Attack Risk in older women

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Calcium supplements are often prescribed to older (postmenopausal) women to maintain bone health. Sometimes they are combined with vitamin D, but it’s still unclear whether taking calcium supplements, with or without vitamin D, can affect the heart.

A team of researchers at the University of Auckland re-analysed a study previously done by The Women's Heath Initiative (WHI) to estimate the real effects of calcium supplements, with or without vitamin D, on the risk of cardiovascular events.

They analysed data from 16,718 women who were not taking calcium supplements at the start of the trial and found that those allocated to combined calcium and vitamin D supplements were at an increased risk of cardiovascular events, especially heart attack.

By contrast, in women who were taking personal calcium supplements at the start of the trial, combined calcium and vitamin D supplements did not alter their cardiovascular risk.

The authors suspect that the abrupt change in blood calcium levels after taking a supplement causes the adverse effect, rather than it being related to the total amount of calcium consumed. High blood calcium levels are linked to calcification (hardening) of the arteries, which may also help to explain these results.

Further analyses – adding data from 13 other trials, involving 29,000 people altogether – also found consistent increases in the risk of heart attack and stroke associated with taking calcium supplements, with or without vitamin D, leading the authors to conclude that these data justify a reassessment of the use of calcium supplements in older people.

Because of study limitations, researchers say “it is not possible to provide reassurance that calcium supplements given with vitamin D are related with certainty to increased cardiovascular risk. Clearly further studies are needed and the debate remains ongoing.”