Quick Facts

• Heart attack survivors who received targeted vitamin D therapy had 50% lower risk of second heart attacks
• 85% of heart attack patients had insufficient vitamin D levels below 40 ng/mL at study start
• Treatment required personalized dosing up to 5,000 IU daily with quarterly blood monitoring

Heart attack survivors can slash their risk of a second cardiac event by half through targeted vitamin D therapy, according to groundbreaking research presented at the 2025 American Heart Association Scientific Sessions.

The TARGET-D trial followed 630 heart attack patients for up to eight years. Researchers found that patients who received personalized vitamin D supplementation with regular blood monitoring had a 50% reduction in repeat heart attacks compared to standard care.

“We observed no adverse outcomes when giving patients higher doses of vitamin D3 supplementation, and significantly reduced the risk of another heart attack, which are exciting results,” said principal investigator Heidi May, PhD.

The study enrolled patients within one month of their heart attack. Participants averaged 63 years old, 78% were men, and 48% had experienced a previous heart attack. Researchers discovered that 85% of heart attack patients had insufficient vitamin D levels below 40 ng/mL at enrollment.

The treatment group received targeted vitamin D3 supplementation with dose adjustments every three months based on blood testing. The goal was to achieve and maintain vitamin D levels above 40 ng/mL but not over 80 ng/mL. More than half of patients required initial doses of 5,000 international units daily, significantly higher than typical supplement recommendations of 600-800 IU.

“Previous studies just gave patients supplementation without regularly checking blood levels of vitamin D to determine what supplementation achieved,” May said. “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.”

Of the 630 patients enrolled, 107 experienced a major cardiac event during the follow-up period. The findings represent the first study to demonstrate that customizing vitamin D doses for heart attack survivors reduces their risk of another heart attack by half.

The results carry global significance as one-half to two-thirds of people worldwide have low vitamin D levels. Approximately 1 billion people suffer from severe vitamin D deficiency globally.

Previous clinical trials that provided standard vitamin D supplementation doses failed to show measurable reductions in heart disease risk. The TARGET-D trial’s personalized approach marks a departure from one-size-fits-all dosing strategies.

External experts note that while the 50% risk reduction is encouraging, the study involved higher-risk patients and results may not apply to lower-risk populations. Further research is necessary to assess the efficacy of vitamin D supplementation in individuals without previous heart attacks.

Researchers plan a larger clinical trial to confirm these findings and evaluate whether targeted vitamin D management reduces the risk of other cardiovascular diseases. The study has not yet undergone peer review or been published in a medical journal.

Read more: This Vitamin Slashes The Risk Of A Second Heart Attack By 50%, Study Shows