Australian researchers found omega-3 fatty acids are the most promising nutrient for alleviating the symptoms of depression.
Omega-3 fatty acids - DHA and EPA - have been linked in numerous studies to cognitive, cardiovascular and eye health. This review study was conducted at the University of Sydney. It analyzed prior published studies relating to depression in order to see how dietary manipulation might alleviate its effects. The conclusion that omega-3 fatty acids offer the most hope in terms of nutritional support for depression support a suggestion of increased fish and fish oil consumption. Fish oil from cold water marine fish contains a high concentration of the long-chain omega-3 fatty acids DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid).
“A review of epidemiological data suggests that there is a link between depression and fish consumption, and although it is true that correlation is not causation, there is evidence that fish and fish oils may be protective against depression,” wrote lead researcher, Dianne Volker.
The review, published in the November 2006 issue of the Dieticians Association of Australia's Nutrition and Dietetics journal, drew conclusions from previous studies from around the world, with 103 sources cited. Depression is among the leading causes of disability worldwide and affects about 121 million people, according to the World Health Organization.
The study refers to studies which have linked people with extremely high consumption of cold-water fish, such as the Inuit in Greenland, to virtually non-existent rates of depression. The study nonetheless highlighted the fact that there are numerous social and environmental factors that cause depression.
The other ingredients cited in the study for their potential benefits for depression, were the amino acid tryptophan, vitamins B6, B12, folate and S-adenosyl-L-methionine (SAMe). However, omega-3 fatty acids carried significantly more evidence in the literature, according to the researchers.
They said that membrane lipid abnormalities are thought to occur in depression and omega-3s, in particular DHA, are depleted in depressed subjects.
The study also drew attention to weaknesses in the nature of studies that exist on depression and omega-3. “Although there is a growing body of literature on the role of fish and fish oil consumption in depression – most of which report results from epidemiological and observational studies – clinical experimental data in this area remain scarce,” said the researchers.
DHA and EPA are omega-3 fatty acids commonly found in fish and fish oil. Neptune krill oil is another important source of DHA and EPA.
Depression is a serious illness, affecting more than one million Australians each year. It causes significant morbidity and is a major risk factor for deliberate self-harm and suicide. Depression was traditionally viewed as a personality weakness, for which few treatment options were available. The simplistic view that depression is a personality weakness has changed in recent times. Depression is now widely recognised as a mood disorder with underlying biological (biochemical and genetic) and psychosocial causes and as such is responsive to a number of different treatments. The aim of the present paper is to review the literature related to dietary manipulation and how manipulation may assist in treating this illness. Evidence reviewed supports a potential therapeutic benefit of n-3 polyunsaturated fatty acids for the alleviation of negative symptoms associated with depression. Omega-3 polyunsaturated fatty acids, optimal omega balance, folate, tryptophan, vitamin B6, B12, S-adenosyl-L-methionine and Hypericum perforatum may all serve as adjuncts to psychosocial and pharmacological therapies, with positive implications for long-term prognosis.
Dianne VOLKER, Jade NG (2006). Depression: Does nutrition have an adjunctive treatment role? Nutrition & Dietetics 63 (4), 213–226. doi:10.1111/j.1747-0080.2006.00109.x