Vitamin D cuts heart attack risk by 52%. Why? Brandon Ballinger Jan 30, 2026
A new study showed that Vitamin D supplementation can reduce heart attacks by 52%. This is important since heart attacks are the #1 cause of death, about one billion people worldwide are deficient in Vitamin D, and supplementing vitamin D is cheap.
TARGET-D is a randomized trial in people with who previously had a heart attack, presented at American Heart Association (AHA) Scientific Sessions. In the study, they measured vitamin D blood levels every 3 months, and adjusted vitamin D3 doses to keep vitamin D levels within a target range of 40–80 ng/mL.
Participants in the experiment arm who stayed within 40-80 ng/mL of vitamin D had a 52% lower risk of a repeat heart attack.
Why would that be? Vitamin D is not part of the standard six biomarkers for cardiovascular health (blood pressure, ApoB, Lp(a), hs-CRP, eGFR, and A1c) that we’ve written about extensively here.
In the rest of this post, we’ll try to explain why. We’ll cover the physiological mechanisms that link Vitamin D₃ and D₂ to heart health, how to measure vitamin D, specific ways to get more vitamin D, and potential future work.
Vitamin D comes in two main forms. Vitamin D₃ (cholecalciferol) is made in your skin when UVB sunlight hits it, and also in animal foods. Vitamin D₂ (ergocalciferol) is from plants and fungi.
Neither is active on its own, but is converted by the liver and kidneys into a calcitriol, a form that binds to Vitamin D receptors in the nucleus of many cells.
Multiple chemical pathways absorb or create vitamin D.
Vitamin D then regulates hundreds of genes with broad effects. It increases calcium absorption in the intestines (children without vitamin D get rickets). It regulates adaptive immunity (inflammation). It regulates blood pressure through effects on the renin-angiotensin system.
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