Do calcium supplements raise the risk of heart attacks?

Reviews that found a higher risk

• A 2021 review pooled 13 double-blind, placebo-controlled trials. Calcium supplements raised the risk of cardiovascular disease by 15% and of coronary heart disease by 16%, mainly in healthy women after menopause.^[1]
• An earlier analysis by one research group found 27% to 31% more heart attacks and 12% to 20% more strokes.^[4] In 2025, an author of that group put the higher risk of heart attack at 10% to 20%.^[3]
• The largest trial gave 36,282 women calcium with vitamin D or a placebo for 7 years, with a median total follow-up of 22.3 years. There were 6% more deaths from cardiovascular disease (2,621 against 2,420) and 7% fewer deaths from cancer (1,817 against 1,943). Deaths from all causes did not differ, and there was no overall effect on total cardiovascular disease. The analysis could not separate the effects of calcium and vitamin D.^[5]

Reviews that found no clear risk

• A 2015 review in women after menopause pooled 18 trials with 63,563 people. The risk ratio was 1.02 for coronary heart disease, from the 5 trials that reported it, and 1.08 for heart attack, and neither result differed clearly from no effect.^[6]
• A 2016 review of 4 trials and 27 observational studies found no link between calcium and cardiovascular disease within the upper limit of 2,000 to 2,500 mg a day. The National Osteoporosis Foundation paid for it.^[7]
• A 2023 review of 12 trials found no link with heart attack, stroke, heart failure admission or death.^[2]
• EFSA found no established link between long-term calcium intake and cardiovascular disease.^[8]

Why the reviews disagree

Cardiovascular events were only a secondary question in all the trials.^[7] One research group argues that the result for heart attack depends on two choices. The first is whether to count women in the largest trial who already took calcium when it began. The second is whether to count one open trial in which the groups differed at the start.^[9] Very high intakes, above the upper limits, have little data.^[7]

Why it may happen

These steps are a theory, based mostly on studies of blood markers:^[3]

1. A large dose of calcium raises blood calcium for about 8 hours.^[3][10]
2. During those hours blood clots more easily, and calcium is more likely to form deposits.^[3]
3. Blood pressure is more than 5 mmHg higher than with placebo.^[3]
4. Genetic studies link higher blood calcium with cardiovascular disease.^[3]

The rise in blood calcium did not shrink after 3 months of daily use, and citrate and carbonate did not differ.^[10]

Food or supplements

Dietary calcium does not appear to be a risk factor for the heart.^[3] Food and supplements raise bone density by about the same amount.^[11] One group of authors suggests that food may be preferable, because it has not been linked to heart problems.^[4]

Who should be careful

Trials and studies point to two groups. Trials in people with impaired kidney function suggest a higher cardiovascular risk.^[4] The UK Biobank study followed 434,374 people. Regular calcium supplements were linked to 34% more cardiovascular disease in people with diabetes, and to no increase in people without diabetes. This kind of study cannot prove cause.^[12]

An expert panel in the US judged that calcium intakes up to the upper limit are safe for the heart.^[13] People with heart disease, kidney disease or diabetes should ask a doctor or pharmacist first.^[4][12]