Heart attack risk higher with calcium, says study
TAKING calcium supplements — a common treatment to strengthen bones — may put healthy older women at higher risk of heart attacks. New Zealand researchers followed nearly 1500 women for up to five years — half of whom took calcium, while the rest took dummy pills — and found there were
upward trends’’ in rates of heart attack, stroke and other heart problems among women taking the calcium.
The results appear to contradict the expectations raised by some previous studies, which suggested calcium may have a protective effect on the heart. However, the extent of any increase in heart risk is hard to determine from the new study.
The women directly involved in the research, all of whom were healthy and aged over 55, appeared to have double the relative risk of heart attack if they took calcium.
But the authors said that this risk was halved — to the point where it might no longer be statistically significant — after they used hospital admission data to factor in other heart incidents that were not picked up during the trial itself.
The authors of the study, published online this week by the British Medical Journal, conceded the results were not conclusive’’.
But they did suggest that high calcium intakes might have an adverse effect’’ on heart health, particularly in elderly people with poor kidney function.
The present data do not permit definitive conclusions to be reached in this regard but do flag cardiac health as an area of concern in relation to calcium use,’’ wrote the authors, from the University of Auckland.
Australian experts praised the researchers’ methods but said the findings should not scare people away from calcium if their dietary intake was deficient.
John Eisman, director of the Bone and Mineral Research Program at Sydney’s Garvan Institute of Medical Research, said the results showed that over the five years of the study, there was a difference of just 10 women who had heart attack, stroke or sudden death between the 732 women in the calcium group and the 739 women who took dummy pills.
That means if you had 1000 women treated (with calcium) for a year, it’s potentially possible that three women would have one of these events,’’ Professor Eisman said.
It’s hard to know if this (effect of calcium) is real or not.
I think all you can say is, there might be a small risk — and that people shouldn’t think that calcium is some sort of panacea that cures everything.’’
People whose diets contained little calcium would be advised to continue taking supplements, while those with adequate diets might want to reconsider, he said.
Another expert, Professor Jack Martin, from the Bone, Joint and Cancer Unit at St Vincent’s Institute in Melbourne, said the study was small and the results would need to be replicated in larger trials before any change in current practice were to be considered’’.