Study Asserts a Dark Side to Calcium Supplements

(July 30) -- Calcium supplements, an oft-touted aid in the fight against bone loss and osteoporosis, might actually do more harm than good.

That's the suggestion of a growing body of research, that applies only to supplements. The calcium derived from food products, like dairy, tofu and fortified cereals, carries myriad health benefits.

What are the current recommendations for calcium supplementation?

Osteoporosis is estimated to afflict 10 million Americans, and doctors often recommend calcium supplementation to stave off the progression of the illness.

Current federal guidelines advise women over 50 -- those most at risk of developing osteoporosis -- to ingest 1,200 milligrams of calcium a day, through food or supplementation. Those already diagnosed with osteoporosis are often prescribed more, up to 1,500 mg a day.

Consider that a cup of milk contains 300 mg of calcium -- an elderly woman would need five glasses a day to meet the quota.

What's the latest research?

An analysis of 11 different studies on calcium supplements, published this week in the British Medical Journal, came to some troubling conclusions.

Risk of heart attack soared 31 percent among study participants ingesting more than 500 mg of calcium via supplements each day. Risk of stroke and death were also elevated, but to a lesser extent.

The research team behind the analysis, along with authors of an editorial accompanying the study, all urged more research to determine exactly why calcium supplements are linked to cardiovascular events.

"As calcium supplements are widely used, these modest increases in risk of cardiovascular disease might translate into a large burden of disease in the population," the study reads. "A reassessment of the role of calcium supplements in the management of osteoporosis is warranted."

How can I obtain adequate calcium safely?

First and foremost, opt for food sources.

"[Supplements] seem to be unnecessary in adults with an adequate diet," reads an editorial accompanying the study. "Given the uncertain benefits of calcium supplements, any level of risk is unwarranted."

Patients taking calcium supplements should weigh the pros and cons with their doctor, and consider a combined supplement of calcium and vitamin D.

This analysis evaluated calcium-only supplements, but vitamin D helps the body absorb calcium more readily, and several studies have found no adverse effects among women taking combined supplements.