New Study Says Certain Supplements Do Not Prevent Cancer or Heart Disease

Supplementation with vitamin D and omega-3 did not result in a lower incidence of cancer or cardiovascular events compared with placebo, according to a study published in the New England Journal of Medicine. 

The nationwide, randomized, placebo-controlled VITAL (VITamin D and OmegA-3 TriaL) trial included 25,871 Americans of various ethnicities who were older than 50 years and had no history of cancer, heart attack, stroke, or other forms of heart disease. 

Participants were randomized to receive vitamin D 2,000 IU per day and omega-3 1 g per day or placebo.  

During a median follow-up of 5.3 years, there was no significant difference in heart disease or cancer incidence between those taking supplements versus placebo. Cancer was diagnosed in 1,617 participants, including 793 in the vitamin D group and 824 in the placebo group (hazard ratio [HR] = 0.96; 95% CI, 0.88-1.06; P=0.47). There were 341 deaths from cancer. A major cardiovascular event occurred in 805 participants, including 396 in the vitamin D group and 409 in the placebo group (HR=0.97; 95% CI, 0.85-1.12; P=0.69).  

However, during the study, deaths from cancer were reduced by 25% for those who took vitamin D supplements. There was also a 28% reduction in heart attacks in those taking omega-3 supplements. There was a 77% reduction in heart attacks linked to omega-3 consumption for African-American participants. For those who did not eat the recommended weekly serving of fish, supplements were linked to a 40% reduction in heart attacks; however, this association was not observed for people who did eat enough fish. 

The researchers observed no excess risks of hypercalcemia or other adverse events. 

Longer-term follow-up could provide additional information on these findings. 

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SourceNew England Journal of Medicine