Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease (VITAL trial)

Researchers randomly gave 25,871 generally healthy adults a daily vitamin D pill or a placebo, an inactive pill. The participants were men aged 50 or older and women aged 55 or older in the United States. After about 5 years, vitamin D did not significantly lower new cancer diagnoses or major cardiovascular events, meaning heart attacks, strokes, or deaths from heart disease. The dose was 2,000 international units daily, and the study did not test whether vitamin D helps people with a severe deficiency.

What this means for you: For generally healthy older adults, this study does not support buying vitamin D supplements to prevent cancer or heart disease. Vitamin D may still be useful for other reasons or for people with low levels, but that was not what this study tested.