A groundbreaking study from Intermountain Health has revealed a remarkable finding: targeted vitamin D3 supplementation can slash the risk of a second heart attack in half for patients who have already experienced one. This is a huge deal, and it could change the way we approach heart health.
Conducted by heart and vascular experts at Intermountain Health, the research focused on a 'target to treat' approach. This meant closely monitoring heart attack patients' vitamin D levels and adjusting their vitamin D3 dosage to achieve optimal levels. The results, presented at the 2025 American Heart Association Scientific Sessions in New Orleans, are truly promising.
Dr. Heidi May, a cardiovascular epidemiologist and the study's principal investigator, stated that the results are exciting because they observed no adverse outcomes when administering higher doses of vitamin D3. But here's where it gets controversial: the study showed a significant reduction in the risk of another heart attack.
Why is this so important? Well, between 50% and 66% of people worldwide have low vitamin D levels. Historically, we got enough vitamin D from the sun. However, with lifestyle changes and the push to reduce skin cancer risk, sun exposure has decreased. This means we need to get vitamin D from other sources, like supplements.
Previous studies tried standard supplementation without much success. Intermountain researchers hypothesized that it's more about reaching a specific vitamin D level than just taking supplements. And this is the part most people miss: The Intermountain study, called the TARGET-D trial, enrolled patients from April 2017 to May 2023, following them until March 2025. The study included 630 Intermountain Health patients who had a heart attack within a month of enrollment. The participants were split into two groups: one receiving no vitamin D management and the other receiving targeted vitamin D3 treatment.
In the targeted treatment group, the goal was to raise blood vitamin D levels above 40 ng/mL. Shockingly, 85% of the heart attack patients had insufficient vitamin D levels. The study found that more than 50% of those in the targeted treatment group needed an initial vitamin D3 dose of 5,000 international units (IU), while current suggestions are usually between 600 to 800 IU.
Patients in the targeted treatment group had their vitamin D levels checked annually to ensure they were above 40 ng/mL. Those below the target had their dosage adjusted and were tested every three months, then annually once they reached the target.
Researchers then monitored the patients for major cardiac events (MACE), including heart attack, heart failure hospitalization, stroke, or death. Out of the 630 patients, 107 experienced a major cardiac event. While there wasn't a significant difference in overall MACE risk between the groups, the risk of a follow-up heart attack was reduced by half in those receiving targeted vitamin D management.
The next step? Larger clinical trials to confirm these findings. This will help researchers assess whether targeted vitamin D management can reduce the risk of developing other cardiovascular diseases, according to Dr. May.
What do you think? Does this study change your perspective on vitamin D supplementation? Are you surprised by the high initial dosages? Share your thoughts in the comments below!
