Calcium Supplements Linked To Heart Attack Risk

A new study suggests that taking calcium supplements increases the risk of having a heart attack, Swiss and German researchers reported Wednesday. The finding adds to the growing body of evidence for minimal benefits.

The results seem to suggest that calcium consumed as part of a normal diet can, indeed, increase bone density and perhaps help lower blood pressure, but that supplements may be too risky for most people to take.

A team headed by epidemiologist Sabine Rohrmann of the University of Zurich studied almost 24,000 participants in a German arm of the European Prospective Investigation into Cancer and Nutrition. All participants were between the ages of 35 and 64 when they enrolled in the study  between 1994 and 1998. Normal diets were assessed for the preceding 12 months and they were quizzed about whether they regularly took vitamin and mineral supplements.

Participants were then tracked for 11 years, during which the researchers recorded 354 heart attacks, 260 strokes and 267 deaths related to either heart attacks or strokes.

The team reported in the journal Heart that those who had a moderate amount of calcium in their diet (820 milligrams daily) had a 31% lower risk of having a heart attack than those in the bottom 25% of calcium consumption, but those with a daily intake of more than 1100 mg did not have a lower risk. There was no evidence that any level of calcium intake in the diet affected stroke risk.

But when the team considered supplements, they found that those who took calcium supplements regularly were 86% more likely to have a heart attack than those who used no supplements. For those who took only calcium supplements, and no others, the risk doubled.

In an editorial accompanying the report, Dr. Ian R. Reid and Dr. Mark J. Bolland of the University of Auckland in New Zealand note that earlier studies have shown similar, albeit smaller effects.

“Calcium supplements have been widely embraced by doctors and the public, on the grounds that they are a natural and therefore safe way of preventing osteoporotic fractures,” they wrote. “It is now becoming clear that taking this micronutrient in one or two daily [doses] is not natural, in that it does not reproduce the same metabolic effects as calcium in food.”

Those studies were smaller, however, and researchers did not put tremendous amounts of faith in them.

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