How vitamin D and fish oil affect risk of heart attack, stroke and cancer

While earlier trials have examined whether fish oil or other supplements may prevent heart attack or stroke in patients with a history of heart disease or at very high risk of such disease, VITAL is the first large trial of omega-3 fatty acids for primary prevention – that is, preventing the first occurrence – of heart disease in a general population.

VITAL was designed to test the independent effects of vitamin D and omega-3 supplements, as well as to test for synergy between the two. Participants were divided into four groups: vitamin D (2000 IU/day of vitamin D? [cholecalciferol]) plus omega-3s (1g/day of Omacor [known as Lovaza in the U.S.]); vitamin D plus placebo omega-3s; omega-3s plus placebo vitamin D; and placebos for both.

Researchers compared those who received active omega-3s with those who received placebo. After a median of five years of treatment, 805 participants had suffered a major adverse cardiovascular event, such as a heart attack or stroke (386 in the omega-3 group and 419 in the placebo group). While these rates did not statistically differ, VITAL found a significant 28 percent reduction in risk of heart attack among participants taking the omega-3 fatty acid supplements (145 cases in the omega-3 group and 200 in the placebo group). This effect was greater among people who had lower fish intake (a 40 percent reduction). No significant differences were seen for cancer outcomes.

Source: VITAL study: How vitamin D and fish oil affect risk of heart attack, stroke and cancer