Overall, the researchers found that people who consumed the most fish lowered their risk of depression by 17 percent compared to those who ate the least.
“Studies we reviewed indicated that high fish consumption can reduce the incidence of depression, which may indicate a potential causal relationship between fish consumption and depression,” said lead researcher Fang Li, of the department of epidemiology and health statistics at the Medical College of Qingdao University in China.
But this association was only statistically significant for studies done in Europe, the researchers said. They didn’t find the same benefit when they looked at studies done in North America, Asia, Australia or South America. The researchers don’t know why the association was only significant for fish consumption in Europe.
The study was also only able to show an association between eating fish and the risk fordepression, not that eating fish causes a lower risk for depression, Li said.
Still, Li thinks there may be reasons why fish may have an effect on depression.
“Fish is rich in multiple beneficial nutrients, including omega-3 fatty acids, high-quality protein, vitamins and minerals, which were associated with decreased risk of depression from our study,” Li said.
The researchers pointed out that it’s possible that the omega-3 fatty acids in fish may change the structure of brain membranes, or these acids may alter the way certain neurotransmitters work. Neurotransmitters are the brain’s chemical messengers, sending information from brain cell to brain cell. Some neurotransmitters, such as dopamine and serotonin, are thought to be involved in depression, the researchers said.