According to a new study, omega-3 supplements may not be as beneficial for cognitive decline as previously thought.

Consuming fish oil tablets has long been thought to encourage better performance in memory tests as well as other long-term brain functions, according to KRWG News22.

A new study has discovered that taking fish oil supplements, also known as omega-3, does not help mental decline or memory function, contradicting many observational studies over many years.

“Contrary to popular belief, we didn’t see any benefit of omega-3 supplements for stopping cognitive decline,” said Emily Chew, the lead researcher of the study.

The study consisted of over 3,000 participants with an average age of 72. Part of the group was given fish oil tablets while the other part were given a placebo. Then, the cognitive function of each person was tested every two years.

Researchers found no difference in the cognitive scores of people who were given fish oil compared with the placebo group after five years.

The findings were published in the medical journal JAMA and clearly contradicted some epidemiological evidence that taking the supplements of omega-3 would lower the risk of dementia.

Although the researchers are confident in their claim, Dr. Chew also recognizes that cognitive decline could take place over decades, rather than years, and that their study may not have been long enough. Dr. Chew also added that a short-term supplementation given too late in the development of the disease may not be effective.

“It is possible that eating foods rather than taking any specific single supplement may have an effect,” said Dr Chew, deputy clinical director at the National Eye Institute, part of the National Institutes of Health which funded the study.

In 2012 Cochrane Collaboration, an evidence-based medicine group, published a review of the research on fish oil supplements preventing dementia. But the review found the claim was short of any direct evidence and that further research was needed to see if the supplements could in fact work on a long-term basis.

A clinician and researcher at Neuroscience Research Australia, William Brooks, said studies suggested the supplement was working but control trials were the gold standard that establish the effect of any drug or supplement.

“We’ve seen it in Alzheimer’s Disease that epidemiology evidence suggested hormone replacement therapy may prevent it in women, but then RCT’s found women on the therapy actually had a higher incidence of Alzheimer’s Disease,” Brooks said.