Millions of Americans take calcium pills to protect their bones, especially women after menopause. A study published in the Journal of the American Heart Association in April 2026 suggests those with existing heart disease should stop and ask their doctor first.
Researchers in Hong Kong matched 35,440 adults with major cardiovascular disease one-to-one on age, sex and clinical risk factors.
Users of calcium had a 10 percent higher risk of a new cardiovascular event than non-users, with a hazard ratio of 1.10. Acute myocardial infarction risk also rose by 10 percent, and stroke risk climbed by 6 percent.
The signal was strongest in one subgroup. People taking calcium alone, without vitamin D, had a 21 percent higher recurrence risk. When calcium was combined with vitamin D, the excess risk disappeared. Men also showed a bigger effect than women.
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Where the concern first came from
The 2026 findings echo earlier randomized trial data.
A meta-analysis of 13 double-blind, placebo-controlled trials published in Nutrients in January 2021 found calcium supplements raised cardiovascular disease risk by 15 percent and coronary heart disease risk by 16 percent.
The effect was concentrated in healthy postmenopausal women, the group most likely to take them.
In absolute numbers, that works out to roughly 8.6 extra cardiovascular events per 1,000 people on calcium supplements. The baseline risk is low, but not zero.
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Not every study points the same way. Mayo Clinic's cardiology team notes that the evidence is mixed, with some analyses finding no link at all, and recommends discussing supplements with a healthcare professional.
Dietary calcium looks different
A key distinction runs through the literature. Calcium from food does not appear to carry the same signal as calcium from pills, and researchers keep separating the two when they analyze the data.
The National Institutes of Health puts the recommended daily intake at 1,000 milligrams for most adults, and 1,200 milligrams for women over 50 and men over 70. Reaching that from food is straightforward for most people.
Milk, yogurt and cheese are the traditional sources, but broccoli, kale, canned salmon and sardines with bones, tofu made with calcium sulfate, and fortified plant milks or cereals all contribute.
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For those already in the habit of taking a daily calcium pill, the broader evidence on whether these supplements actually protect the bones they are marketed for has grown less flattering in recent years.
What to do if you have heart disease
If you have a history of a heart attack, stroke or coronary artery disease, talk to your doctor before starting or continuing a calcium-only supplement.
Adding vitamin D, or getting more calcium from meals instead of pills, may be safer options. Anyone without a cardiac history should still weigh whether they need a supplement at all, particularly if food already covers the daily target.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.