Depression: eating more fish helps mood and positively affects the brain

Consuming fish, especially those rich in Omega 3, at least twice a week would help women reduce their risk of depression. In men, however, this link is not found. The hypothesis is that long-chain polyunsaturated fatty acids, in combination with female hormones, may act on the brain, positively affecting mood.

This is the discovery made by researchers at the Menzies Research Institute in Tasmania, Australia, and published in the past few days in the American Journal of Epidemiology.

Omega-3s are essential for the functioning of neurons

Omega-3 fatty acids are key components of the cell membranes of neurons. In particular, DHA (docosahexaenoic acid) is the fatty acid most represented in the nervous system. The role of Omega-3s is to maintain membrane fluidity and ensure growth and communication between brain cells. Numerous studies have suggested that Omega-3 fatty acids may protective effects against neurological diseases such as Alzheimer's and act positively on mood and behavior.

Fish consumption: effects in men and women

During the study, 1,400 men and women, aged 26 to 36, were monitored, and they filled out a diary on their eating habits, which had to indicate the frequency and type of fish and seafood consumed. In addition, information on each person's mental health status was collected. After 5 years of observations, also taking into account lifestyles, education and profession, the scholars found a relationship between fish consumption and the incidence of depression. Specifically, in women it was evident that each additional portion of fish consumed per week was associated with 6 percent lower risk of depression. 

In women who consumed fish at least twice a week from the beginning of the study, the likelihood of depressive episodes was 25% lower than in those who consumed less. In men, this relationship was not evident. The difference in effects would be due to the combination of omega-3s with female hormones (estrogen and progesterone) useful for maintaining proper brain function. Another hypothesis sees involvement in the low amount of seafood consumed by men, who tend to take Omega-3 from other sources, especially meat. The Omega-3 fatty acids that possess beneficial effects on the brain are the long-chain ones, contained mainly in fish oil.

Fish oil as part of a balanced diet

The results of this study suggest that fish has positive effects on women's mental well-being, although it remains to be clarified by what mechanism this occurs. This finding is very important considering that there are about 5 million citizens in Britain alone who are affected by depression and that females, between the ages of 16 and 42, are more than twice as likely to be victims. It is clear that the human body, including the brain, requires proper nutrition to function properly and that in some cases, deficiencies can also manifest themselves in depression.

It is therefore advisable to eat at least two servings of fish per week, including one with species high in Omega 3, such as mackerel, fresh tuna, salmon or sardines. Shellfish and white fish can also help reduce deficiencies in minerals such as zinc and iodine. According to researchers, consumption of fish oil containing Omega-3 can promote health and be part of a balanced diet. 

Source: Smith KJ, Sanderson K, McNaughton SA, Gall SL, Dwyer T, Venn AJ. "Longitudinal associations between fish consumption and depression in young adults." Am J Epidemiol. 2014 May 15;179(10):1228-35.