Updated

If your daily routine involves taking a fish oil pill for your brain health, you may want to rethink that. In the largest and longest in duration study of its kind, researchers found that taking omega-3 supplements did not slow cognitive decline, The Washington Post reported.

The study included 4,000 participants at risk for developing age-related macular degeneration, a major cause of vision loss among older Americans. They found omega-3 supplements had no statistically significant effect on cognitive function.

"The supplements just don't cut it," Emily Chew, deputy clinical director at the National Eye Institute, part of the National Institutes of Health, told The Washington Post. "If people are thinking [taking them] is going to help cognitive function, it's not going to do so among the older age group."

Researchers added that eating foods naturally high in omega-3 fatty acids, such as salmon, flaxseed and walnuts, was a better choice for all-around brain and heart health.

Study participants were randomly assigned to one of four groups and were tested on their immediate recall, attention and memory at the beginning of the study, then two and four years later.

The study, published in the Journal of the American Medical Association, only looked at the impact of supplements, researchers noted, not foods high in omega-3.

Study participants had an average age of 73.

"We don't know whether these supplements might be beneficial at an earlier age," Chew told The Washington Post. "At 73, it's very hard to turn the clock back."

Click for more from The Washington Post.