Calcium supplements to boost bone health may increase the risk for heart attack among older people, says a new research conducted by scientists in New Zealand.

Several elderly people consume calcium supplements to remedy the bone depletion in osteoporosis. These supplements do little in contributing to the bone health but at the same time adversely raise the risk for getting a heart disease.

Researchers from the Department of Medicine in the Faculty of Medical and Health Sciences at the University of Auckland reviewed 11 randomized, controlled trials involving 11,921 people. Their meta-analysis of the already published data found a near 30 percent increased likelihood of a heart attack among people older than 40 who were taking calcium supplements.

Calcium supplements can increase blood levels of calcium above the normal level, causing changes in blood chemistry, which could be dangerous in people at risk for heart attacks. The study has also noted a small but statistically insignificant increase in the risk for stroke and death among those taking supplements.

Even though the increased risk for a heart attack was a modest one, the findings remained consistent even after taking into account age, gender and the type of supplement, the researchers said.

"When you look at major trials where people have been randomly assigned to take calcium or placebo, there is an increase in the risk of heart attack in the people who were randomly assigned to take calcium," says lead researcher, Dr. Ian Reid, in his report published online in BMJ.

The extent of that increased risk is enough to completely counterbalance the small beneficial effect that calcium tablets have on numbers of fractures. Rather than relying on calcium supplements, people get their required calcium, if possible, from foods, the researchers suggest.