In this study, 1,471 healthy post-menopausal women, average age 74, were given either a daily calcium supplement of 1,000 mg/day or a placebo. They were followed for five years.
Of the 732 women who took supplements, 31 suffered a heart attack. Of the 739 women who got a placebo, 21 women who got a placebo - two percent lower heart attack risk than the supplement group.
Previous research has shown that taking calcium supplements might protect against vascular disease by lowering levels of bad cholesterol in the blood. Because calcium supplements raise blood calcium levels, it's thought that taking supplements may speed up the formation of calcium deposits in the arteries that could lead to heart attack.
The researchers cautioned these findings aren't the "definitive word on the subject", but said future studies need to further investigate the relationship between calcium supplements and heart attack.
Health Canada recommends 1,200 mg of calcium per day for women over 50 years old. One serving of milk or milk alternative - one cup (250 ml) of milk or fortified soy beverage or 3/4 cup (175 g) of yogurt - provides 300 milligrams of calcium.
For more information on women and heart attack risk, check out Leslie Beck's Foods that Fight Disease.
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