Do calcium supplements raise the risk of dying from heart problems?

By Sophie Ramsey

BMJ Group News

What do we know already?

Calcium is the most plentiful mineral in the body and it is essential for strong bones and teeth. You can get calcium from many foods, including dairy products, spinach, kale, and soybeans.

As you get older, your body doesn’t take up calcium as well as it used to. This increases the risk of osteoporosis, a condition marked by thin and weak bones that break easily. Many older people, particularly women, take calcium supplements to help prevent or treat this bone disease. However, recent studies have raised concern that these supplements may increase the risk of heart attacks and other serious heart and circulation problems.

To learn more, researchers gathered data on more than 388,000 men and women, aged 50 to 71, who took part in a large US health study. The participants filled in questionnaires on their usual diet, including their use of calcium supplements and multivitamins. The researchers then recorded, over an average of 12 years, how many people died of heart and circulation problems, and whether there was a link with their calcium intake.

What does the new study say?

The researchers found no connection between calcium intake and the risk of dying from heart and circulation problems among women. This was true when the researchers looked at the women’s total calcium intake, as well as the calcium they got just from supplements and just from foods.

For men, however, those who had higher levels of calcium from supplements (1,000 milligrams or more a day) were 20 percent more likely to die from heart and circulation problems than men who didn’t take any calcium supplements. This sounds like a large increase in risk, but bear in mind that the chance of dying was low overall, with less than 2 in 100 men who took the most calcium dying of these problems during the study.

As with women, the researchers found no link between men’s calcium intake from foods, and their risk of dying from heart and circulation problems.

How reliable is the research?

This was a large study that followed participants for more than a decade. The researchers took into account several things that might have affected people’s chances of heart and circulation problems. These included people’s age, whether they smoked or were overweight, and whether they exercised and were in good health. These things strengthen the study’s findings.

Even so, we need to be a bit cautious about these results, as this type of study can’t prove that calcium supplements increased men’s risk of dying from heart and circulation problems. There could have been something else about the diets or lifestyles of men who took calcium supplements that increased their risk instead. Also, when using questionnaires to gather information about people’s diets there is room for error, as people may not accurately remember or record what they ate or drank.

What does this mean for me?

Guidelines recommend that most adults get 700 milligrams (mg) of calcium a day, preferably from foods. However, your doctor may advise you to get more calcium - possibly from supplements - if you are at risk of osteoporosis or already have the disease.

If your doctor has recommended taking calcium supplements, you shouldn’t stop taking them based on these findings. We still need more research to confirm these results. However, if you are concerned, you might talk to your doctor about ways to get enough calcium in your diet without taking supplements.