Could too much calcium cause heart disease?
Posted By Patrick J. Skerrett On August 12, 2010
Oh, the ruckus a single study can raise. A report about calcium and cardiovascular disease had people from San Diego to Caribou, Maine worriedly calling their doctors or throwing away the calcium supplements they were taking to keep their bones strong.
Here’s what prompted the concern: New Zealand researchers pooled the results of 11 randomized, controlled trials—the so-called gold standard of medical research—comparing the effects of calcium supplements and placebo on preventing osteoporosis or colon cancer. All the trials also had information on the volunteers’ cardiovascular health. As reported online in the BMJ, more of the volunteers taking calcium had heart attacks, stroke, or died suddenly than did those taking the placebo. Media reports duly noted a 30% increased risk of cardiovascular disease with calcium supplements, which sounds scary. Another way to put the findings: 5.8% of those taking calcium had a cardiovascular event, compared with 5.5% of those taking placebo.
This publication is just another piece of the calcium puzzle. It isn’t a practice changer. Some prior studies have shown that taking calcium supplements is linked to cardiovascular disease, others haven’t.
The connection between calcium and cardiovascular disease is plausible. Calcium deposits are part of artery-clogging plaque. They also contribute to stiffening of the arteries and interfere with the action of heart valves. But whether there is a direct connection between the amount of calcium in the bloodstream (calcium supplements increase blood calcium levels) and cardiovascular problems isn’t yet known.
An even bigger unanswered question is how much calcium the average person needs each day to keep bones strong and healthy. At one end of the spectrum, the World Health Organization says 400 to 500 milligrams (mg) of calcium a day are needed to prevent osteoporosis. At the other end, the official recommendation for Americans is 1,000 mg/day from ages 19 to 50 and 1,200 mg/day after that.
Given the uncertainty about the balance of benefits and risks of calcium supplements, it’s probably best not to rely just on this mineral to keep your bones strong and prevent bone-thinning osteoporosis. Other options include:
A single study rarely changes health recommendations. This New Zealand study alone definitely shouldn’t change advice on calcium supplement. It should, though, nudge you to talk with your doctor about calcium, and do other things to protect your bones.
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