I have reproduced some extracts and I have added some comments.
A study by researchers at Sydney's Black Dog Institute found there was a plausible link between high rates of depression and bipolar disorder and low consumption of Omega-3 fatty acids. Full paper here.(pdf)
These important fats are found in seafood, wild game and plants, but are rapidly disappearing from the western diet.
There has been, for some years now, an increase in popularity for game meats and seafood. Also, the popularity of pasture fed farm animals (as opposed to grain fed) is increasing as well.This is an encouraging sign as people are increasing their Omega-3 EFAs, albeit, unknowingly.
The study also found that mothers who had lower levels of Omega-3 in their breast milk were more likely to suffer from postnatal depression.
Lead researcher and institute director Professor Gordon Parker (above) said Omega-3 polyunsaturated fatty acids, found in fish, have in many cases been replaced by saturated fats from farm animals and Omega-6 polyunsaturated fatty acids from common vegetable oils.
"These changes have led to a 10-fold increase in the ratio of omega-6 to Omega-3 fatty acids in the Western diet," Prof Parker said. The Omega-3 to Omega-6 ration is a subject touched upon by Drs. Eades and Dr.Loren Cordain. I strongly suggest you browse their websites for further research.
Research has shown that changes in the level of fatty acids in the diet are linked to the rise in cardiovascular disease, depression and other neurological disorders.
Omega-3 supplements are becoming increasingly popular among people with mood disorders because they're believed to be a practical and simple treatment. Good examples of Omega-3 supplements are Cod liver oil (liquid form) and Flaxseed oil capsules.
Prof Parker said much work is still needed to be done to determine which Omega-3 fatty acid, and in what ratio to Omega-6 fatty acids, was likely to have the greatest benefit and in what dosage. As stated above, people are increasing their Omega-3 oils by eating more fish, pasture feed beef, game meat and supplements. Research by Dr. Loren Cordain and Drs. Eades (also mentioned above) suggest that the ideal ratio of Omega-3 to Omega-6 should be as close to 1:1 as is possible.