Tailored Vitamin D Doses Reduce Heart Attack Risk by 52% in Heart Disease Patients

Adults with heart disease who received vitamin D doses tailored to achieve optimal blood levels reduced their risk of heart attack by 52% compared to those who did not have their vitamin D levels managed, according to preliminary research from the TARGET-D clinical trial. The findings, to be presented at the American Heart Association's Scientific Sessions 2025, suggest that personalized vitamin D supplementation could represent a significant advancement in cardiovascular care for patients with existing heart conditions.

The study enrolled 630 adults with acute coronary syndrome treated at Intermountain Medical Center in Utah from April 2017 to May 2023, with an average follow-up of 4.2 years. Participants were randomly assigned to either a standard care group that received no vitamin D monitoring or a treatment group that received targeted vitamin D supplementation with doses adjusted every three months based on blood testing. The goal was to achieve and maintain vitamin D levels between 40-80 ng/mL, a range many experts consider optimal for heart health.

Heidi T. May, Ph.D., M.S.P.H., FAHA, principal investigator of TARGET-D and an epidemiologist at Intermountain Health, explained the study's innovative approach. "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."

The study revealed that more than 85% of participants began the research with vitamin D levels below 40 ng/mL, indicating widespread vitamin D insufficiency among heart disease patients. Perhaps most notably, nearly 52% of participants in the treatment group required more than 5,000 IU of vitamin D daily to reach target blood levels—more than six times the FDA-recommended daily intake of 800 IU. Researchers monitored both vitamin D and calcium levels throughout the study to prevent vitamin D toxicity, reducing or stopping doses if levels rose above 80 ng/mL.

While the tailored vitamin D approach did not significantly reduce the primary outcome of death, heart failure hospitalization or stroke, the substantial reduction in heart attack risk specifically represents an important finding. A total of 107 major cardiac events occurred during the study period, with 15.7% occurring in the treatment group and 18.4% in the standard care group. The American Heart Association provides additional health information about dietary supplements at https://www.heart.org/en/health-topics/healthy-living/dietary-supplements-hype-or-help-for-good-health.

The study's implications for clinical practice could be substantial, potentially shifting how healthcare providers approach vitamin D supplementation in cardiac patients. May emphasized that these results could improve patient care by focusing on blood tests for vitamin D levels and tailoring doses accordingly. "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," she added.

However, researchers caution that the study has several limitations. Only adults with diagnosed heart disease were included, so the results may not apply to people without heart disease. The smaller number of participants limited analysis of other conditions and outcomes, and approximately 90% of participants self-identified as white, indicating the need for additional research across diverse populations. The abstract is available in the American Heart Association's Scientific Sessions 2025 Online Program Planner at https://professional.heart.org/en/meetings/scientific-sessions.

May and her colleagues emphasized that more clinical trials are needed to determine whether targeted vitamin D treatment could help prevent heart disease before a first cardiac event. The American Heart Association notes that the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal. Before adding or changing any vitamin regimen, the Association encourages people with heart disease to consult their cardiologist.