Are calcium supplements bad for your heart?
Calcium supplements may be associated with an increased cardiac risk, but not all studies confirm this. It is preferable to obtain calcium from your diet, and discuss with your doctor whether a supplement is truly necessary for you.
Calcium supplements may increase the risk of a heart attack. Several large analyses of placebo-controlled trials found an increased risk of approximately 27 to 31% for heart attack and of 15 to 16% for cardiovascular disease and coronary heart disease in general. This effect was seen mainly in healthy postmenopausal women. A more recent analysis from 2023, however, found no statistically significant association, nor for stroke, heart failure, or mortality. The studies do not fully contradict each other, but they are not in agreement either.
The contrast with calcium from food is striking. Larger population studies find no clear association between dietary calcium and an increased cardiac risk. That distinction matters: a supplement puts a large amount of calcium into your blood all at once, whereas calcium from food is absorbed gradually and slowly. It is hypothesised that this peak in blood calcium after taking a supplement contributes to calcification in blood vessels, but this mechanism has not yet been definitively proven.
Beyond the possible cardiac risks, there are other drawbacks. Calcium supplements increase the risk of kidney stones by approximately 17%, and the risk of hospital admission due to gastrointestinal complaints doubles. At the same time, the evidence that supplements actually prevent bone fractures is weak: several large studies found no fracture prevention, and for hip fractures in particular, evidence is almost entirely absent.
What does this mean for you? If you have no demonstrated calcium deficiency and no severe vitamin D deficiency, the benefits of calcium supplements are small and the risks are real. The safest way to obtain calcium is through a varied diet, such as dairy products, legumes, and green vegetables. If you have been prescribed calcium supplements, for example following a question about bone fractures, discuss with your doctor whether the dose and the necessity are still appropriate.
This answer is based on several large analyses that pooled results from randomised placebo-controlled trials, including one analysis with more than 43,000 participants. The findings on cardiac risk are not unambiguous: earlier analyses found a significantly elevated risk, while the most recent one (2023) did not. The researchers themselves identify inconsistency between studies as a core problem. For kidney stones, gastrointestinal risk, and the absence of fracture prevention, the evidence is more consistent. The evidence on calcium from food is thinner and relies on population research without a randomised design, meaning cause and effect cannot be demonstrated there.