Vitamin D3 Found to Cut Second Heart Attack Risk by Half: Study

Low vitamin D has long been linked to poor heart health, yet past trials using fixed supplementation doses failed to reduce heart attack rates. The Intermountain researchers took a different tack: instead of one-size-fits-all dosing, they closely monitored blood vitamin D levels and tailored supplements to raise levels above 40 nanograms per milliliter, a target considered ideal. This “target-to-treat” strategy ensured each patient received the right amount to impact their heart health.

The TARGET-D trial enrolled 630 heart attack survivors within one month of their event and followed them through early 2025. Patients were randomly assigned either to standard care or to active vitamin D3 management involving dose adjustments and frequent monitoring.

Initially, 85% of participants had levels below 40 ng/mL, with many requiring high doses of 5,000 IU—far above typical recommendations. Blood levels were checked every three months in those not yet at target and yearly once the optimal range was achieved.

Although the overall incidence of major cardiac events (including strokes and heart failure) did not differ significantly, targeted vitamin D3 treatment dramatically cut the chance of a second heart attack by 50%. Importantly, no adverse effects were observed with higher doses, underscoring safety along with effectiveness.

Researchers plan larger trials to confirm and expand on these promising results, aiming to solidify vitamin D3’s role in cardiac care. This study marks a pivotal shift from generic supplementation toward personalized, monitored micronutrient therapy that could save lives after a heart attack.