Tailored Vitamin D Dosing Reduces Heart Attack Risk by 52% in Heart Disease Patients

Adults with heart disease who received vitamin D doses tailored to reach optimal blood levels reduced their risk of heart attack by 52% compared to those who did not have their vitamin D levels optimized, according to preliminary research from the TARGET-D randomized clinical trial. The study, to be presented at the American Heart Association's Scientific Sessions 2025, represents a significant shift from previous vitamin D research by focusing on personalized dosing rather than standardized supplementation.

The TARGET-D trial included 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 an average age of 63 years, 78% were men, and 48% had experienced a previous heart attack. More than 85% of all participants began the study with vitamin D levels below 40 ng/mL, a level many experts consider insufficient for optimal health.

Unlike earlier vitamin D randomized trials that used standard doses for all participants, the TARGET-D trial personalized supplementation based on individual blood test results. "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," said Heidi T. May, Ph.D., M.S.P.H., FAHA, principal investigator of TARGET-D and an epidemiologist at Intermountain Health in Salt Lake City, Utah.

The study's methodology involved randomizing participants into two groups: a standard care group that received no vitamin D level management and a treatment group that received tailored vitamin D supplementation with doses adjusted every three months until blood levels exceeded 40 ng/mL. 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. Excessive vitamin D can lead to hypercalcemia, kidney failure and abnormal heart rhythm.

One of the most striking findings was that nearly 52% of participants in the treatment group required more than 5,000 IU of vitamin D daily to reach target blood levels of greater than 40 ng/mL. This dosage represents more than six times the FDA-recommended daily intake of 800 IU, highlighting the individual variability in vitamin D requirements and absorption.

While the study primarily focused on whether optimal vitamin D levels could reduce the risk of serious cardiovascular events including heart attack, heart failure hospitalization, stroke or death, researchers found that tailored vitamin D supplementation specifically benefited heart attack prevention. The treatment did not significantly reduce the primary outcome of death, heart failure hospitalization or stroke collectively, but demonstrated clear effectiveness against heart attacks specifically.

The implications of these findings could transform cardiovascular care by emphasizing the importance of personalized vitamin D supplementation based on blood testing. Current clinical practice typically involves standardized dosing without consideration of individual baseline levels or absorption capabilities. The study suggests that routine vitamin D testing and targeted supplementation could become an important component of cardiovascular risk reduction strategies for patients with established heart disease.

However, researchers emphasized several limitations that warrant consideration. The study included only adults with diagnosed heart disease, so results may not apply to people without cardiovascular conditions. The relatively small number of participants limited more comprehensive analysis of other conditions and outcomes. Additionally, the study population lacked diversity, with approximately 90% self-identifying as white, indicating the need for additional research across different racial and ethnic groups.

May and her colleagues stress 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 encourages people with heart disease to consult their cardiologist before adding or changing any vitamin regimen. Additional information about the study can be found in the American Heart Association's Scientific Sessions 2025 Online Program Planner at https://professional.heart.org/en/meetings/scientific-sessions.

This research represents an important step toward personalized cardiovascular care, suggesting that individually tailored approaches to nutritional supplementation may provide significant benefits beyond standardized recommendations. As cardiovascular disease remains a leading cause of mortality worldwide, such personalized interventions could contribute to improved outcomes for millions of patients living with heart conditions.