Despite concerns raised in recent years, calcium supplements may not boost the risk of heart attack and stroke after all, according to a new research analysis published in the peer-reviewed journal Heart, Lung and Circulation.

Many older adults, especially women, take calcium supplements to help treat or prevent the bone-thinning disease osteoporosis. However, some studies have found a link between calcium use and an increased risk of heart attack and other cardiovascular problems.

Now the new analysis, which pooled the results of a dozen randomized controlled trials, indicates otherwise: Researchers found that among nearly 89,000 trial participants in all, those given calcium supplements had no greater risk of suffering a heart attack or stroke. Nor were they any more likely to be hospitalized for heart failure or die of cardiovascular causes.

The study looked at 12 previously published clinical trials where participants were randomly assigned to take a calcium supplement (with or without vitamin D) or a placebo. Many of the trials tested the effects of calcium on bone density or fractures, mostly in postmenopausal women; some looked at whether calcium helped prevent recurrent colon polyps.

The trials lasted anywhere from 18 months to 12 years, and most participants took 1,000 to 1,200 milligrams (mg) of calcium per day—in line with what’s generally recommended for adults.

Individually, none of the trials found any greater risk of stroke, heart failure, or cardiovascular death among calcium users. When it came to heart attack risk, three trials reached varying conclusions: Calcium either raised, slashed, or had no impact on the odds.

When the researchers pooled the data from the different trials, they found no link between calcium use and any of the cardiovascular ills studied.

Why would calcium supplements potentially be bad for the cardiovascular system? It’s plausible, based on the fact that they raise blood calcium levels—and more so than dietary calcium, the researchers noted in the paper. And one postulated mechanism is that “increased blood calcium levels cause vascular calcification leading to long-term pathogenic atherosclerotic change”—that is, the development of “artery-clogging” plaque.

That, however, has never been proven. And, in fact, some studies have found that calcium supplements may help lower blood pressure and cholesterol levels, and that could lead to less plaque.

Based on the new analysis, there is much less support for the idea that taking calcium poses a cardiovascular threat, on average. For any one person, though, the decision to use calcium (and vitamin D) depends on individual circumstances.

Here are some things to keep in mind:

• In general, women older than 50 should get 1,200 mg of calcium per day—from diet and, as needed, supplements. Men should get 1,000 mg per day up to age 70; after that, they should aim for 1,200 mg.
• Many foods contain calcium. Milk, cheese, and yogurt are probably the best known sources, but others include leafy greens like kale and broccoli; canned salmon and sardines (if you eat the soft bones); tofu (as much as 350 mg of calcium per 3-ounce serving, when prepared with calcium sulfate as a coagulant—check products’ nutrition labels); and fortified plant-based milks and orange juice (typically as much as milk, about 300 mg per cup).
• Talk to your doctor about bone health, including whether and when you should undergo bone density screening. The U.S. Preventive Services Task Force recommends screening for women older than 65 and for certain women under 65, depending on their risk factors. Men with certain risk factors should also be screened. Depending on the results, calcium and vitamin D supplements may be recommended. But they are generally considered only part of the story. A healthy diet and weight-bearing exercises—such as brisk walking or jogging, and strength training with weights, resistance bands, or weight machines—can help keep bones strong.
• If you have osteoporosis, your doctor may also recommend medications that slow bone loss and reduce the risk of fractures.