Do Calcium Pills Raise Heart Attack Risk? What the 2010 Scare Found, and What Came After

Where the worry came from

In 2010, researchers pooled randomized, placebo-controlled trials of calcium supplements (500 mg/day or more) in adults with an average age over 40, lasting more than a year ^[2]. Five trials supplied patient-level data on 8,151 people followed for a median of 3.6 years ^[2].

In those five trials, 143 people taking calcium had a heart attack compared with 111 on placebo, a hazard ratio of 1.31 ^[2]. Increases in stroke, the combined end point of heart attack, stroke or sudden death, and death were not statistically significant ^[2]. Trial-level data from 11,921 participants pointed the same way ^[2].

One detail is easy to miss: the analysis looked at calcium supplements given without vitamin D ^[2]. It is a single analysis's harm signal, and other evidence points the other way, which is why the monograph grades it C ^[2][1].

What larger and later evidence says

ODS summarizes the research on calcium and heart risk as mixed, and points to evidence on the reassuring side. In the Nurses' Health Study, 74,245 women aged 30 to 55 who took more than 1,000 mg/day of supplemental calcium had no higher cardiovascular risk over 24 years than women who took none ^[1].

An expert panel convened by the National Osteoporosis Foundation and the American Society for Preventive Cardiology concluded, on moderate-quality evidence, that calcium from foods or supplements, with or without vitamin D, neither raises nor lowers cardiovascular risk ^[1]. The societies judged intakes that do not exceed the upper limit to be safe from a cardiovascular standpoint ^[1].

The other trade-off: kidney stones

The best-documented downside is not the heart. In the Women's Health Initiative, 36,282 women aged 50 to 79 took 1,000 mg of calcium carbonate plus 400 IU of vitamin D daily, or placebo, for an average of 7.0 years ^[3]. Self-reported urinary tract stones were 17% more common with the supplements: 449 women versus 381 ^[3].

What you get in return for bones

Calcium supplements raised bone density by 0.7% to 1.8% across 51 trials in adults over 50, and the gain did not grow after the first year ^[4]. The authors judged it unlikely to cut fractures meaningfully ^[4].

Fracture trials disagree. A 2017 meta-analysis of community-dwelling adults over 50 found no link between calcium, vitamin D or both and fewer fractures ^[5]. A 2016 meta-analysis that also included adults in care homes found 15% fewer total fractures and 30% fewer hip fractures with calcium plus vitamin D ^[6]. For the vitamin D side, see what the VITAL trial found on fractures.

Questions worth asking your clinician

Add up what you already get from food before adding a pill. The RDA for women 51 and older and everyone over 70 is 1,200 mg/day, and the upper limit from age 51 is 2,000 mg/day, counting food and supplements together ^[1].

People with a history of kidney stones or heart disease have the most reason to talk the decision through, given the stone finding and the mixed heart data ^[3][2][1]. If you are weighing forms and doses, read calcium citrate vs carbonate, and see vitamin K2 and arterial calcium for the K2 question. Everything is collected on the calcium monograph.