Medical Edge Newspaper Column

Several Factors to Consider Before Taking Calcium Supplements

April 15, 2011
Dear Mayo Clinic:
I suffered a heart attack three years ago, at age 42. I have bad osteopenia and am required to take calcium supplements. I have heard that calcium supplements can increase the risk of a heart attack. Is there any truth to this?

Answer:
Your body requires calcium to build and maintain strong bones, and many people regularly take calcium supplements to ensure they are getting the calcium they need. Although it's not definitive, a 2010 study suggested a link between calcium supplements and an increased risk of heart attack. Important to note, though, is that the calcium supplements in question are those that contain calcium alone. The research did not address the more common practices of taking calcium supplements along with vitamin D supplements or calcium supplements that include vitamin D. Also not considered were multivitamin supplements.

The study that investigated the possible link between calcium supplements and risk of cardiovascular disease, published in July 2010, was a meta-analysis. This type of research involves reviewing and analyzing data and findings from a group of clinical research trials focused on the same topic. In this case, researchers examined 15 clinical trials — involving 12,000 patients — that studied the effect on cardiovascular health of supplements containing only calcium. After analyzing the combined data of these studies, researchers concluded that calcium supplements were associated with about a 30 percent increase in the risk of heart attacks. There was no significant relationship between calcium in food and beverages (dietary calcium) and risk of heart attack.

Before you decide about calcium supplements based on this research, keep several factors in mind. First, the vast majority of people who take calcium supplements don't — and generally shouldn't — take calcium alone. Instead, calcium should be combined with vitamin D because vitamin D helps the body absorb and use calcium properly. The combination of calcium and vitamin D supplements is not associated with an increased risk of heart attack. In fact, other research has linked vitamin D to a decreased risk of cardiovascular problems.

Second, the clinical trials analyzed for the meta-analysis were not designed to study cardiovascular disease. The studies were designed to primarily evaluate the effect of calcium on bone disease. Therefore, conclusions about cardiovascular disease taken from these studies may not be quite as accurate as they would have been if the studies had focused specifically on that topic.

Third, the findings of the meta-analysis are not final. Before any definitive recommendations can be made about a possible link between calcium supplements and heart attacks, a significant amount of additional research is still needed.

Also, as with most vitamins and minerals, remember that your diet is the best way to get the calcium you need. Many good sources of dietary calcium exist, including dairy products, dark green leafy vegetables, some types of fish such as sardines and canned salmon, and calcium-fortified foods and beverages like cereals and fruit juices.

Many healthy people can get the Recommended Dietary Allowance (RDA) of calcium from dietary sources. For women age 50 or younger and men age 70 or younger, the RDA is 1,000 milligrams (mg) of calcium a day. For women older than 50 and men older than 70, it's 1,200 mg daily. If a healthy person's diet isn't providing the RDA of calcium, a calcium supplement (along with vitamin D) can make up the difference.

For someone in your situation, who has a medical condition that requires a calcium supplement, a typical supplement that combines calcium and vitamin D should be safe and sufficient to meet your calcium needs.

There is an additional consideration in people who have kidney failure or a predisposition to kidney stones. Some research has shown that calcium supplements may increase health risks in these patients. If you have a kidney disorder, talk to your doctor before taking calcium supplements.

— Donald Hensrud, M.D., Preventive Medicine, Mayo Clinic, Rochester, Minn.