Key points from article :
For years, vitamin D was hailed as a potential cure-all after observational studies linked low blood levels to higher risks of cancer, heart disease, diabetes, and autoimmune disorders. That enthusiasm cooled when large randomized trials—most notably the VITAL trial, led by researchers in the US and published in major medical journals—found that giving vitamin D supplements to generally healthy adults did not significantly reduce heart attacks, strokes, or cancer. As a result, clinical guidelines were revised to recommend modest daily supplementation and to discourage routine vitamin D testing in healthy people.
This new article revisits that settled view in light of a more recent randomized study called TARGET-D. Unlike earlier trials, TARGET-D focused on people at very high cardiovascular risk—patients leaving hospital after a heart attack. Instead of giving everyone a fixed dose, clinicians in the intervention group tested patients’ vitamin D levels and adjusted doses to push levels above a defined target. Participants were followed for just over four years for major adverse cardiovascular events such as death, heart attack, stroke, or heart failure.
Overall, the trial did not show a statistically significant reduction in the main combined outcome. However, when researchers looked specifically at repeat heart attacks, they found a notable difference: about 8% of patients in usual care had another heart attack, compared with roughly 4% in the vitamin D–managed group—a 52% relative reduction. This intriguing signal suggests vitamin D might help in certain high-risk settings, even though the absolute benefit was small and uncertainty remains.
The article stresses caution. TARGET-D was not blinded, raising concerns about bias, and the primary endpoint was technically negative. Some other outcomes even trended in the opposite direction. Still, the findings complicate the simple narrative that vitamin D “does nothing” and suggest that targeted, treat-to-level strategies in high-risk patients may deserve further study. For now, the evidence isn’t strong enough to change guidelines—but it is enough to reopen the conversation.
