Calcium Supplements Unsafe for the Heart

A new study by researchers at Auckland University in New Zealand has found that large doses of calcium supplements can prove harmful for the heart. The study contradicts findings of studies conducted five years previously which suggested that calcium supplements can lower heart disease risk.

Calcium supplements are generally prescribed to men and especially women over the age of 40 to help prevent their bones from weakening due to loss of calcium caused by osteoporosis. Nearly half of all women and one third of all men over the age of 60 suffer a fracture on account of this condition.

The research team from Auckland University studied 1500 postmenopausal women over a period of five years. The women were randomly assigned to take a 1g supplement of calcium and a placebo pill. At the end of the study period, the researchers found that 36 of the women taking calcium supplements had suffered a heart attack, compared to 22 of those who were taking a placebo pill.

There were a few deaths due to cardiac-related conditions during the study period; however none of these could be attributed to the calcium supplements. According to study lead author Professor Ian Reid, their study did not necessarily prove that all calcium supplements are responsible for heart attacks; he was however worried by the trend.

Referring to other smaller studies that had similar findings, he said that there was build-up of calcium in the heart vessels of people with heart disease and taking extra calcium could worsen this build-up.

Based on their findings, Professor Reid advised those trial participants who had heart problems or poor kidney function to find an alternate method to prevent osteoporosis. “If you are elderly and you have heart disease, you should probably be looking after your bones in other ways than with high calcium intakes,” he said. He suggested a 50% reduction in dose for other people.

The current findings by Professor Reid’s team are in stark contrast to those of their study conducted in 2002. In that study, the researchers had found that calcium improved cholesterol balance. Following that study, they had suggested that calcium supplements could help reduce the risk of heart disease and stroke.

Medical experts on the other hand believe the risk of heart disease should be assessed for individual patients and weighed against the benefits they might receive from calcium supplements. “There are other ways of looking after your bones,” said Professor Geoffrey Horne, a Wellington Orthopaedic surgeon and formerly a scientific adviser to Osteoporosis New Zealand.

“It’s all a matter of balancing risks. If you take some of the pharmacologically active drugs, they too have risks... every time you put something in your mouth you are taking a risk,” Professor Horne said.

In the opinion of Dr. Norman Shape, Medical Director of the Heart Foundation, the new study is an important one and people taking calcium supplements should discuss their risks with their doctor.

“There will be people who are at very high risk of osteoporosis where the treatment is well justified because the benefits will outweigh any risks and there will be those at relatively low risk where calcium supplementation is going to provide little benefit and will still carry this sort of risk,” Dr. Shape said.

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