Bone-building calcium pills increase heart attack risk: study

20 April 2011 One Comment

Joseph Hall, Health Reporter

The Toronto Star

There is growing evidence that the calcium pills millions of older women take to save their bones are breaking their hearts.

A new study shows post-menopausal women who begin calcium supplement therapy to ward off or treat bone-depleting osteoporosis significantly increase their risk for both heart attacks and strokes.

The study authors say its findings warrant a reconsideration of the nearly universal use of the mineral supplement to treat the disease.

“If you treat 1,000 people with calcium for five years . . . you cause six more heart attacks or strokes and you prevent three fractures,” says Dr. Ian Reid, a University of Auckland endocrinologist.

“So you’re actually appearing to do more harm than good,” says Reid, the senior study author.

Jane Aubin, head of musculoskeletal health with the Canadian Institutes of Health Research, called the study a thoughtful and careful analysis of the data, but said the risk findings would need to be confirmed by further research.

Aubin added the results do give greater impetus to groups like hers to promote calcium intakes through healthy diets.

The study shows older women who begin taking calcium — at any available dose — increase their risk of heart attack by 25 per cent in the first year. Their risk of stroke increases about 15 per cent over a longer period. The study was released Tuesday by the British Medical Journal.

The study, which looked at 29,000 post-menopausal women, was a follow-up to an earlier paper by the same group that showed similar cardiovascular risk increases. But the original paper looked at women taking calcium alone without the effects of a vitamin D additive.

For the current paper, Reid’s group accumulated data on women from around the world who had just begun calcium plus vitamin D regimens. These women were then compared to study recruits who had been put on inert placebo pills.

Reid says the cardiovascular risks with the vitamin D additive were identical to those in his original calcium-only research.

“We concluded it wasn’t anything to do with the presence or absence of vitamin D,” he says.

Importantly, Reid says women who take in the mineral through healthy, calcium-rich foods don’t appear to run the same risks as those who use supplements.

Toronto’s Maureen Colford, who developed osteoporosis eight years ago after ovarian failure, says the study would not cause her to quit her daily calcium supplementation.

“There’s a study out every five seconds that something is good or something is bad (in osteoporosis),” says Colford, 42.

Colford, who is lactose intolerant, says she can’t get calcium through milk, one of the richest natural sources. The only way for her to maintain normal levels is to supplement, which she says she will continue doing.

The obvious thinking has been that calcium, essential for hard bones, also increases hardening of the arteries, a primary cause of cardiovascular ailments. But Reid says the risk, especially for heart attacks, rises so fast after beginning the therapy that the supplementary calcium would not likely have time to build up on arterial walls.

However, calcium can also affect blood-clotting platelets and abnormalities in their production could be contributing to the heart-attack risks, he says.

Reid also says the heart risks rise equally regardless of the dosage.

There are also alternate and safe medicines available to reduce fracture risks in patients with osteoporosis, he says.

Osteoporosis afflicts as many as 2 million Canadians and strikes twice as many women as men. It is most common in people over the age of 50.

Originally published on healthzone.ca April 19, 2011