People who eat a lot of fish may have a slightly lower risk of depression, according to a new analysis of previous studies.
In their analysis, researchers looked at 26 studies that involved a total of 150,278 people and examined the relationship between depression and the consumption of fish. Ten of the studies were conducted in Europe and seven were done in North America, with the remaining ones conducted in Asia, Oceania and South America.
When the researchers analyzed the studies conducted in Europe, they found that the people who consumed the most fish had a 17 percent lower risk of depression than those who ate the least amount of fish.
"Higher fish consumption may be beneficial in the primary prevention of depression," the researchers wrote in the study. [7 Ways Depression Differs in Men and Women]
When the researchers analyzed all the data by gender, they found that the men who ate the most fish had a 20 percent lower risk of depression than those who ate the least amount of fish. In women who ate the most fish, their risk of depression was reduced by 16 percent, compared to the women who ate the least fish.
Although the associations between high fish consumption and lower depression risk were found for the studies conducted in Europe, they were not found for the studies conducted in the other continents, the researchers noted. "This might [be] because a smaller number of participants cannot reach statistical significance easily," said study author Fang Li of Qingdao University in Shandong, China.
Because the studies included in the analysis were observational (the researchers did not, for example, ask people to start eating more fish and measure the effects), a cause-and-effect relationship between fish consumption and the risk of depression could not be established, the researchers said.
Moreover, the researchers did not have information about the types of fish the people in the studies ate, Li said. More research is needed to see if the association between depression risk and fish consumption varies according to the type of fish consumed, the researchers said.
It is not clear why eating more fish may lower the risk of depression, but there are several mechanisms that could be at work in the link, the researchers said. For instance, previous research has suggested that omega-3 fatty acids in fish could alter the structure of brain cell membranes. It could also be that other fatty acids in fish modify the activity of the neurotransmitters dopamine and serotonin, which are thought to be involved in depression, the researchers said.
But it could also be that people who eat more fish are generally healthier. "High fish consumption may also be related to a healthier diet and better nutritional status, which could contribute to the lower risk of depression," Li told Live Science.
The new study was published today (Sep. 10) in the Journal of Epidemiology & Community Health.