Vitamin D and heart attack: A personalised vitamin D regimen cut the risk of a second heart attack by half in patients who had recently suffered one, according to preliminary results from an Intermountain Health study presented at the American Heart Association Scientific Sessions 2025.
The TARGET-D trial enrolled 630 adults (average age 63; predominantly male) within a month of a myocardial infarction. Participants were randomly assigned to usual care or to a protocol that regularly checked vitamin D levels and adjusted daily D3 supplementation to maintain a target of 40 ng/mL. At enrolment, 87% had low vitamin D levels, with an average of 27 ng/mL; nearly 60% in the treatment arm began at 5,000 IU per day.
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Over follow-up, the targeted-supplement group recorded fewer recurrent heart attacks, 3.8% versus 7.9% in controls, amounting to about a 50% relative reduction. There was no significant difference between groups in the broader composite of major cardiovascular events, which included death, heart failure hospitalisation and stroke.
Researchers said the trial was designed to test whether tailoring vitamin D doses to individual needs, rather than using a one-size-fits-all dose, could influence outcomes after a heart attack. The findings have not yet been published in a peer-reviewed journal.
Outside experts urged caution. Interventional cardiologist Cheng-Han Chen said prior research largely shows association rather than causation between vitamin D status and heart health, though he noted potential mechanisms such as reduced inflammation and lower blood pressure. Lipidology specialist Louis Malinow welcomed the level-targeted approach, arguing that many earlier vitamin D studies did not monitor or individualise dosing. Both said larger, longer trials are needed, including in patients who have not yet had a cardiac event.
Vitamin D, obtained from sunlight, foods such as fortified milk and cereals, and supplements, supports bone, muscle and nerve function and modulates the immune system. The US Food and Nutrition Board recommends 600 IU per day for most adults aged 18–70, but clinicians often prescribe higher doses to correct a deficiency identified on blood testing.
The TARGET-D investigators said they plan a larger study to confirm whether maintaining a specific vitamin D level can reliably lower the risk of repeat heart attacks.
