Calcium: Heart Risk for Older Women?
Study Shows Calcium Supplements May Up Heart Attack Risk in Postmenopausal Women
Calcium, Heart Attack Results continued...
The risk of a heart attack was about 1.5 times greater for those in the supplement group, but the link did not reach statistical significance.
Considered together, strokes, heart attack, or sudden death were more common in those on supplements than on placebo, but the differences -- when taken as a whole -- were statistically only of borderline significance, Reid's team found.
The researchers took into account such factors as cigarette smoking, high cholesterol, and blood pressure problems.
Calcium, Heart Attack: What's the Mechanism?
Reid cautions that the findings must be replicated and plans to do more research on the proposed link.
But he speculates that the calcium supplements may elevate blood calcium levels and possibly speed calcification in blood vessels, which is known to predict the rates of vascular problems such as heart attack.
Second Opinion: Calcium, Heart Attacks
The link between calcium supplements and heart attack suggested by the New Zealand team "seems implausible," says Robert P. Heaney, MD, John A. Creighton University professor at Creighton University in Omaha, Neb., and a long-time researcher of calcium's effect on health.
Typically, Heaney tells WebMD, "Extra calcium doesn't build up in your arteries. The body regulates the blood concentration of calcium.'' Only in people who have lost the ability to regulate calcium levels could the blood concentration of calcium increase, he says, and this condition is rare.
Calcium and Heart Health Advice
Women should keep taking the recommended amounts of calcium, Heaney says. "Postmenopausal women should be getting 1,500 milligrams [a day] through diet and supplements," he says.
The levels recommended by the Institute of Medicine are a bit lower: 1,200 milligrams of calcium for men and women ages 51 and older, and 1,000 milligrams for those 19 to 50.
"Even if it turns out this [proposed link between calcium supplements and heart attacks] is true and replicated [with further research] you have to weigh that against fracture protection," Heaney says of calcium supplements.
Reid disagrees, suggesting women over the age of 70 and some others should rethink calcium supplements.