Researchers from the National Institute for Health Research Bristol Biomedical Research Centre (NIHR Bristol BRC) and the University of Bournemouth have investigated the use of omega-3 fatty acids (n-3PUFAs) as an effective treatment for major depressive disorder (MDD) but found there was no strong evidence to support this.

MDD is characterised by depressed mood or markedly decreased pleasure or interest in everyday activities. It is highly debilitating for the individual and current treatments such as antidepressants or counselling therapies can require long-term engagement.

Recently, researchers have explored various lines of evidence that suggest polyunsaturated fatty acids impact on depressive symptoms. However, this work has created differing results, making it difficult to draw clear conclusions.

The team undertook a Cochrane systematic review, where they analyse all studies on a subject to establish robust evidence and conclusions. The Cochrane Collaboration is an international charity that reviews medical research findings to help health professionals, patients, and policy makers make evidence-based choices about health interventions. They publish systematic reviews of the available research evidence on a range of health topics. The reviews are updated periodically.

This Cochrane review explored whether increased intake of omega-3 fatty acids, found in fatty fish and some other seafood and in some nuts and seeds, have an impact on depressive symptoms compared to other treatments.

They concluded that there is not enough high-quality evidence to determine the effects of omega-3 fatty acids as a treatment for MDD. However, there was a small-to-modest positive effect of using them compared to a placebo treatment, but the size of this effect is unlikely to be meaningful to people with MDD.

Rachel Perry, a lead author on the paper and Systematic Reviewer with the NIHR Bristol BRC’s Nutrition theme, said:

“We need more evidence, particularly to explain the differences between study findings. For example, it would be interesting to look at the differences between individuals who may or may not benefit from n-3PUFAs.

“Future studies should also compare n-3PUFAs with usual antidepressant treatment and investigate the way these treatments may work.”

Paper: Omega‐3 fatty acids for depression in adults, Katherine Appleton et al, Cochrane Database of Systematic Reviews