Like most old wive's tales, the one about fish being brain food seems to be based on some solid science that may one day help treat the ravages of depression.Researchers from Quebec and Ontario are studying the role of a specific fatty acid in treating major depression — eicosapentaenoic acid or EPA — which is largely obtained from omega-3 fatty acids found in fish.The double-blind, randomized, placebo-controlled study of 508 people will be the largest "gold standard" trial of this type of treatment so far, says Dr. François Lesperance, head of the psychiatry department at the Centre hospitalier de l'Université de Montreal. Fish oils have shown some promise in treating depression and bipolar mood disorder since the late 1990s. But the results have been conflicting and the required doses hard to establish.Lesperance hopes to change all that."We are very excited about this project," he says. "For the first time we will have people who are on medication but also people who are taking nothing but our treatment."Past studies have only used omega-3 oils as supplements to antidepressant therapies.Five years ago, Lesperance was studying depression in patients with heart disease at the Montreal Heart Institute. He found they had lower levels of omega-3 in their blood than those who were not depressed. This spurred his interest in the use of fish oils for depression because it has already been established that they are good for heart health as well, he said.The $450,000 study is funded by Isodis Natura, maker of omega-3 oils. However, Lesperance says the company has no influence or involvement beyond that. The study will compare whether depressed people who take 1,050 mg per day of EPA fare better than those who take a placebo (sunflower oil) over eight weeks. It will also measure how well this amount of EPA is tolerated and how safe it is in comparison to the placebo.About two thirds of the brain is made up of fat. To build healthy brain cells you need fatty acids, including a significant amount of "essential" fatty acids that can only be derived from the food we eat. These fall into two groups — omega 3 and omega 6 — both of which are important for brain health.Fatty acids help the brain perform different functions. EPA, for example, is central in the manufacture of photoreceptors that send image messages to the brain. It is also involved in making some neurotransmitters and regulating inflammation.Large amounts of omega-3 oils can interfere with blood clotting in some people. Therefore people with blood clotting diseases and who regularly take any drugs or herbs that thin the blood, such as aspirin or heparin, will not be included in the study.Psychiatric client groups see the study as a positive step."We are always pleased to hear about holistic methods of treating those with a mental health diagnosis," said Shawn Lauzon, executive director of the Ontario Peer Development Initiative.Jennifer Chambers, co-ordinator of the Empowerment Council, located in Toronto, said many in the mental health field are reluctant to look beyond drug cures. But any treatment must be affordable, she says, since few psychiatric clients can afford healthy diets.The study, which is expected to be completed by September 2007, will involve researchers from the University of Montreal, McGill University, Laval University and Queen's University.