A large-scale trial has found no evidence that two popular supplements reduce the risk of cancer or the combined risk for a trio of cardiovascular problems.

JoAnn Manson at Brigham and Women’s Hospital in Boston, Massachusetts, and her colleagues recruited more than 25,000 healthy men and women in their fifties or older including 5106 black participants for a trial examining the effects of fish oil and vitamin D supplements. Some participants took both, others took only one type and the remaining participants took two placebos.

During a median follow-up of 5.3 years, cancer was diagnosed in 1617 participants (793 in the vitamin D group and 824 in the placebo group. A major cardiovascular event occurred in 805 participants (396 in the vitamin D group and 409 in the placebo group. 

The fish-oil group had a lower rate of heart attack but the same rate of total cardiovascular events, a category that included heart attacks, strokes and death from cardiovascular disease.

Vitamin D supplements conferred no clear health benefits against cardiovascular disease or cancer, compared with a placebo.

https://www.nejm.org/doi/10.1056/NEJMoa1809944