Results are published in Thursday’s New England Journal of Medicine. Makers of fish oil supplements helped pay for the study.
Eating fish is known to help protect against heart disease, and the Heart Association recommends it at least twice a week.
“People who choose to eat more fish are more likely to eat heart healthier diets and engage in more physical activity,” and studies testing the benefit of supplements may not be able to completely adjust for differences like these, said Alice Lichtenstein, director of the cardiovascular nutrition lab at Tufts University in Boston.
The results do show that people can’t rely on a pill to make up for a bad diet, she said.
“It is sort of like breaking a fish oil capsule over a hot fudge sundae and expecting the effect of the calories and saturated fat to go away,” she said.