In addition to vitamin D3, the VITAL study also considered the effects of omega-3 fatty acids from fish oil to prevent heart attacks (NEJM, Nov. 10, 2018). The results were disappointing. Concentrated fish oil at a dose of 1 gram per day was no more effective than placebo for preventing cardiovascular catastrophes including strokes. (The investigators provided people with Omacor, a prescription fish oil, or a look-alike placebo.) People taking fish oil were just as likely to die from cancer as those in the placebo arm.
Is Taking Fish Oil to Prevent Heart Attacks a Complete Waste of Effort?
Despite the similar results for the combination of cardiovascular events that the investigators counted as their primary endpoint, fewer people taking fish oil had fatal heart attacks. Participants who were not eating much fish in their regular diets appeared to get more benefit. So did African American volunteers.
Side Effects of Fish Oil to Prevent Heart Attacks:
There were no differences in the unpleasant symptoms such as digestive distress or bleeding reported by people in both groups. Overall, however, the results of fish oil supplementation were disappointing.