Vitamin D may half the risk of second heart attack, study shows

MURRAY — A new study from Intermountain Health suggests vitamin D could play a bigger role in heart health than many people realize.

Researchers found that patients who received targeted vitamin D3 supplementation after a heart attack were far less likely to have a repeat heart attack. The results were presented at the 2025 American Heart Association Scientific Sessions.

"Vitamin D has been an area that our cardiovascular research department has been interested in for a long time," said Dr. Heidi May, a cardiovascular epidemiologist at Intermountain Health and principal investigator of the study.

The clinical trial, known as the TARGET-D trial, followed 630 heart attack patients over several years. Researchers regularly checked participants' vitamin D levels and adjusted doses when needed. At the start of the study, they found that a large majority of the heart attack patients already had low vitamin D levels.

"About 90% of the patients needed some type of supplementation," May said.

Low vitamin D is especially common in Utah, where higher elevations and less winter sunlight can make levels drop.

Instead of giving everyone the same dose, researchers took a more tailored approach: regularly checking blood levels and adjusting vitamin D3 to get patients into a healthy range. Patients were divided into two groups: one received the targeted treatment, while the other did not.

That personalized approach made a significant difference. Patients whose vitamin D levels were actively managed cut their risk of having a second heart attack in half.

"It was quite remarkable," May said.

But doctors stress this isn't about running to the store and loading up on supplements. Vitamin D needs vary from person to person, so they recommend talking with your physician before making any changes.

"We would suggest having a personalized conversation with their own clinician, and based on what their level is, get supplementation for their needs," May said.

Researchers now hope to expand the study to see whether this same targeted approach could help reduce the risk of other heart problems as well.

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