To test the theory, Sydney's Black Dog Institute is recruiting people with mild to moderate depression, aged 21 to 65, for a study to assess the benefits of fish oil supplements rich in Omega-3 fatty acids, The Australian reported Wednesday.
Around 60 percent of the brain is composed of fats, the most important being Omega-3, found in fish oil, and Omega-6.
"There's been studies done internationally showing that countries which eat more fish, such as Japan and Norway, have lower rates of depression," said psychiatrist Anne-Marie Rees. "Also, it's been shown that Omega-3 levels are lower in depressed patients."
The Australian scientists believe Omega-3 is important for the permeability of cell membranes, allowing the free flow of chemicals in and out of neurons in the brain.
Foods rich in Omega-3 include salmon, tuna, sardine and mackerel.
Gordon Parker, head of the Black Dog Institute, said fish oil was relatively free of side effects, although it could slightly increase bleeding in people taking anti-coagulant medication, such as warfarin.
Information on the trial can be found at www.blackdoginstitute.org.au.