There is insufficient evidence to suggest that omega 3 supplements can help in the treatment of major depression, new research has found.

Omega 3 fatty acids are widely considered to be important for good health. They are found naturally in oily fish, such as tuna, sardines and salmon, as well as other foods including walnuts, flaxseeds and tofu.

They are also widely available in over-the-counter supplements. These have become increasingly popular in recent years and some studies have suggested they have a role to play in the treatment of major depression, also known as major depressive disorder.

People with major depression suffer with a depressed mood or lack of pleasure in previously enjoyed activities for a minimum of two weeks, in the absence of any physical cause.

The World Health Organization estimates that major depression accounts for 3% of all ill health around the world and this is expected to increase to 6% or 7% by 2030.

Researchers decided to look into the role of omega 3 supplements in relation to the illness. They assessed 26 trials involving almost 1,500 people. All of the trials investigated the impact of giving a real supplement or a placebo to participants.

The researchers found that while those given the real supplements scored lower for depression than those given a placebo, the effect was small and some of the studies had limitations which undermined the researchers' confidence in the results.

"We found a small-to-modest positive effect of omega 3 fatty acids compared to placebo, but the size of this effect is unlikely to be meaningful to people with depression, and we considered the evidence to be of low or very low quality.

"All studies contributing to our analyses were of direct relevance to our research question, but most of these studies are small and of low quality," commented the study's lead author, Dr Katherine Appleton, of Bournemouth University.

She insisted that currently, ‘we just don't have enough high-quality evidence to determine the effects of omega 3 fatty acids as a treatment for major depressive disorder'.

"It's important that people who suffer from depression are aware of this, so that they can make more informed choices about treatment," she added.

Details of these findings are published in the Cochrane Database of Systematic Reviews.

For more information on depression, see our Depression Clinic here