Intermountain Health Research: Targeted Vitamin D3 Supplementation Cuts Risk of Heart Attack Patients Having a Second Heart Attack in Half

NEW ORLEANS, Nov. 09, 2025 (GLOBE NEWSWIRE) -- A tailored approach of vitamin D3 supplementation in patients who have suffered a heart attack significantly reduces their risk of a second heart attack, according to new research from Intermountain Health heart and vascular experts.

In a large, randomized clinical trial, Intermountain Health researchers have found that treating heart attack patients in a “target to treat” fashion, where patients’ blood levels of vitamin D were monitored and vitamin D3 dosing adjusted to achieve optimal levels, cut their risk of a second heart attack in half.

Results of the study were presented today at the 2025 American Heart Association Scientific Sessions in New Orleans.

The results are promising, said Heidi May, PhD, cardiovascular epidemiologist at Intermountain Health and principal investigator of the study.

“We observed no adverse outcomes when giving patients higher doses of vitamin D3 supplementation, and to significantly reduce the risk of another heart attack, which are exciting results,” said Dr. May. “We’re excited with these results but know we have further work to do to validate these findings.”

The findings are important as between a one-half to two-thirds of people worldwide have low levels of vitamin D.

In the past, most people were able to get enough vitamin D from the sun. However, with changes in lifestyle and recommendations to reduce skin cancer risk, sun exposure has decreased, and individuals must obtain enough vitamin D from alternative sources, such as supplementation with vitamin D3.

Many observational studies have shown low levels of vitamin D to be associated with poor cardiovascular outcomes. However, previous clinical trials provided standard supplementation doses to patients with no reduction in cardiovascular risk found. Intermountain heart researchers wondered if it was more important to increase a patient’s vitamin D level to a certain level rather than just provide supplementation.

“Previous studies just gave patients supplementation without regularly checking blood levels of vitamin D to determine what supplementation achieved,” said Dr. May. “With more targeted treatment, when we checked exactly how supplementation was working and made adjustments, we found that patients had their risk of another heart attack cut in half.”

The Intermountain study, called the TARGET-D trial, enrolled patients from April 2017 to May 2023 and included 630 Intermountain Health patients who had a heart attack within a month of their enrollment. Participants were followed until March 2025 for the occurrence of cardiovascular events.

Researchers randomized study patients into two groups: those who received no management of vitamin D3 by the study and those who received targeted vitamin D3 treatment.

In the vitamin D treatment group, the goal was to raise their blood levels of vitamin D to more than 40 nanograms per ml (ng/mL). Of the heart attack patients enrolled in the study, 85% had insufficient vitamin D3levels (