Research from Intermountain Health reveals that a tailored approach to vitamin D3 supplementation can significantly cut the risk of repeat heart attacks in patients who have previously suffered one. The study, conducted in Salt Lake City, found that monitoring and adjusting vitamin D3 levels in heart attack patients halved their risk of experiencing a second heart attack.
The findings were presented on November 9, 2025, at the American Heart Association Scientific Sessions in New Orleans. According to Heidi May, PhD, a 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.”
The importance of these findings is underscored by the fact that an estimated 50% to 66% of people worldwide have low levels of vitamin D. Traditionally, many individuals obtained sufficient vitamin D from sunlight. However, lifestyle changes and increased skin cancer awareness have led to reduced sun exposure, necessitating alternative sources, such as vitamin D3 supplements.
Previous studies often administered standard doses of vitamin D without monitoring blood levels, resulting in little to no reduction in cardiovascular risks. The Intermountain team sought to determine whether a more personalized approach would yield better outcomes. “Previous studies just gave patients supplementation without regularly checking blood levels of vitamin D to determine what supplementation achieved,” Dr. May explained. “With more targeted treatment, we found that patients had their risk of another heart attack cut in half.”
The study, known as the TARGET-D trial, enrolled 630 patients who had experienced a heart attack within a month of enrollment between April 2017 and May 2023. Participants were monitored until March 2025 for cardiovascular events. The researchers divided the participants into two groups: one received no management of vitamin D3, while the other underwent targeted treatment.
For those in the treatment group, the goal was to raise blood levels of vitamin D above 40 nanograms per milliliter (ng/mL). Notably, 85% of the heart attack patients enrolled had insufficient vitamin D levels. More than 50% of those receiving targeted treatment required an initial dose of 5,000 international units (IU), significantly above the typical recommendation of 600 to 800 IU.
Patients in the treatment group had their vitamin D levels checked annually, with more frequent assessments for those below the target level. Researchers followed the participants to monitor major adverse cardiac events (MACE), which included heart attacks, heart failure hospitalizations, strokes, or death. Out of the 630 patients, 107 experienced a major cardiac event. While no significant difference in MACE risk was observed between the two groups, the targeted vitamin D management group showed a 50% reduction in the risk of a subsequent heart attack.
Looking ahead, Dr. May indicated that the next phase involves conducting a larger clinical trial to further validate these findings. “A larger study group will allow researchers to adequately evaluate whether targeted vitamin D management reduces the risk of developing or reducing the risk of other cardiovascular diseases,” she noted.
These promising results highlight the potential of personalized medicine in addressing cardiovascular health, particularly for those with a history of heart attacks. The research emphasizes the necessity of monitoring vitamin D levels to optimize treatment outcomes and improve patient care in the field of cardiology.
