The benefits of calcium supplements have been the subject of hot debate in recent years, with some studies suggesting that the pills long recommended to prevent osteoporosis might actually be dangerous to the heart. Now, a new study is pushing the pendulum once again in favour of the pills.

In a study to be published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism, Canadian researchers have found a link between taking calcium supplements and a longer lifespan.

While the study was observational and couldn’t determine whether calcium pills actually lengthen one’s life, the researchers say they noticed a link between daily calcium intake and a lower risk of death.

The study was based on data from the large-scale Canadian Multicentre Osteoporosis Study, which monitored the health of 9,033 Canadians between 1995 and 2007. During that period, 1,160 participants died.

The data showed women who said they took daily calcium supplements appeared to have a lower risk of death during the study. Interestingly, the researchers could find no such link in men.

The study's lead author, Dr. David Goltzman, the director of the Calcium Research Laboratory at McGill University in Montreal, says the benefit was seen for women who took doses of up to 1,000 mg of calcium supplements a day, regardless of whether the supplement contained vitamin D.

He added that the link between calcium and longer lifespans in women held regardless of the source of the calcium – whether from dairy foods, non-dairy foods or supplements.

Those taking more than 1,000 mg a day saw no added benefit.

"Our analysis showed that total calcium intake among women was more likely to be beneficial than harmful, and that the same was true of calcium intake from dairy sources, nondairy sources, and supplements," they wrote.

This latest study flies in the face of other research over the last few years that has questioned the benefits of calcium.

Two years ago, a major study in the British Medical Journal found that women taking 1,000 milligrams of calcium and 400 international units (IU) of vitamin D per day were at an increased risk of cardiovascular events -- especially heart attack, stroke and heart disease.

The researchers in that study suggested that calcium supplements could cause sudden spikes in blood levels of calcium, leading to heart attacks and other events. As well, they said that high blood calcium levels over the longer term were linked to calcification or hardening of the arteries.

The BMJ study suggested that calcium from food, on the other hand, would likely not cause the same problems, because the calcium would be absorbed slowly over many hours.

They concluded that the heart risks posed by calcium supplements might outweigh any benefits they offer in reducing bone fractures.

Amid those studies, Health Canada is currently conducting an ongoing review of the benefits and risks of calcium supplements.

The health agency currently recommends most adults aim for a total of 1,000 mg of calcium a day, ideally through their diet. Adults aged 51 and over are advised to aim for 1,200 mg a day.

The authors of this latest study say their research suggests that moderate intake of calcium is safe.

“We feel our evidence suggests that intake of calcium in moderate doses is safe and that it is beneficial for bone health and we would hope that is what women would take away from this,” Goltzman said.

The study was supported by the Canadian Institutes of Health Research, the Dairy Farmers of Canada, Amgen, Merck Frosst Canada, Novartis, and Eli Lilly.

With a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip