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• Posted November 12, 2025

Tailored Doses of Vitamin D Halve Heart Attack Risk

Vitamin D might help people with heart disease avoid a heart attack, if it’s provided in a dose tailored to you by a doctor, a new study says.

Folks provided vitamin D reduced their risk by more than half, researchers reported Sunday at the American Heart Association’s annual meeting in New Orleans.

But there’s a catch — people weren’t downing supplements on their own, but taking custom doses designed to optimize the vitamin D levels in their blood, researchers said.

“We encourage people with heart disease to discuss vitamin D blood testing and targeted dosing with their health care professionals to meet their individual needs,” lead researcher Heidi May, an epidemiologist at Intermountain Health in Salt Lake City, said in a news release.

For the study, researchers recruited 630 adults with heart disease who were treated at Intermountain Medical Center between April 2017 and May 2023.

More than 85% of participants began the study with vitamin D levels below 40ng/mL, a level many experts consider too low for best health, researchers said. Participants were around 63 years old on average and 48% had a previous heart attack.

One group was assigned to take tailored doses of vitamin D to bring their blood levels up, and the rest received care as normal.

“Previous clinical trial research on vitamin D tested the potential impact of the same vitamin D dose for all participants without checking their blood levels first,” May said. “We took a different approach. We checked each participant's vitamin D levels at enrollment and throughout the study, and we adjusted their dose as needed to bring and maintain them in a range of 40-80 ng/mL.” 

In all, 107 major heart health problems occurred during the study period, including heart attack, heart failure, stroke or death. More than 18% occurred in the control group, versus under 16% in the vitamin D group.

People who got personalized vitamin D doses had a 52% lower heart attack risk than those in the control group, results showed.

About half of the participants in the vitamin D group required more than 5,000 IU each day to reach the target blood level — a dose more than six times the daily intake of 800 IU recommended by the U.S. Food and Drug Administration (FDA), researchers noted.

However, the benefit appeared restricted solely to heart attack. The vitamin D didn’t lower patients’ risk of death, heart failure or stroke.

More clinical trials are needed to verify the benefits of targeted vitamin D therapy, both for people who’ve had a heart attack and those who’ve never had one, researchers said. 

Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

The National Institutes of Health has more on vitamin D and heart health.

SOURCE: American Heart Association, news release, Nov. 9, 2025