Popping fish oil supplements believed to help with brain function does not appear to offer brain health benefits, a new study suggests.

The study, which was published by the National Institutes of Health (NIH), appears in the Journal of the American Medical Association and is considered as "one of the largest and longest of its kind," as reported in The Washington Post. It involved a clinical trial conducted on 4,000 older people and ran for five years.

Fish oil supplements have been marketed to be rich in omega-3 fatty acids and are believed to improve cognitive function and prevent heart diseases.

However, there's no hard clinical evidence to prove such claims.

While omega-3 fatty acids are beneficial for good health, taking them in pill form does not provide the same benefit.

The latest study involved patients who suffer from age-related macular degeneration, commonly seen among the elderly.

The study participants, who had an average age of 72 years old, were randomly given placebo or fish oil supplements.

They were then assigned to different cognitive function and memory skills test before the start of the study and again two and four years after.

The cognitive function scores of the participants from either the placebo or the fish oil supplement group decreased over time, suggesting that the supplements did not make any significant difference during the course of the study.

According to Emily Chew, deputy clinical director for NIH's National Eye Institute, the supplements don't bring any benefits to cognitive function, especially for the elderly.

Chew suggested that eating foods that are naturally rich in the beneficial fatty acids, such as walnuts and salmon, is a better way to improve brain health.

Researchers emphasized that the study focused on the effect of supplements and not foods rich in omega-3. Moreover, the study also centered on older people. Chew explained that they still don't know whether or not the supplements will benefit people of younger ages.