Men who have a diet rich in fish saw their risk of depression reduced by a fifth (20%) while women saw their risk decrease by a sixth (16%).
Diet has been recognised as playing an important factor in the risk of getting depression, with a diet rich in fruit, vegetables, fish and whole grains having a positive impact.
But no studies have looked at the individual components of any diet and the beneficial link between eating fish and the risk of depression has remained controversial.
While further studies are needed, researchers suggested omega 3 fatty acids found in fish may alter the microstructure of brain membranes and modify the activity of the neurotransmitters dopamine and serotonin, both of which are thought to be involved in depression.
The high-quality protein, vitamins and minerals found in fish may also help stave off depression, while eating a lot of fish may be an indicator of a healthy and more nutritious diet.
Professor Dongfeng Zhang at the Medical College of Qingdao University, Shandong, China, said: “The association between fish consumption and risk of depression is controversial. Many studies have investigated the associations between food consumption and depression risk.
“Furthermore, a meta-analysis published recently indicated that a healthy dietary pattern, characterised by a high intake of fruits, vegetables, fish and whole grains, was significantly associated with a reduced risk of depression. However, it is not yet clear which component of the dietary pattern would be responsible for the protective effect.”
“Fish, as an important source of ‘n-3’ polyunsaturated fatty acids (n-3 PUFAs), which may play important roles in neural structure and function, has been reported to be associated with depression in several studies.”
The study, published in the Journal of Epidemiology and Community Health, looked at all relevant worldwide studies that examined the association of fish consumption and depression risk printed between 2001 and 2014.
Only the European studies backed up the link between high fish consumption and lower depression risk.
Prof Zhang added: “Higher fish consumption may be beneficial in the primary prevention of depression.
“Future studies are needed to further investigate whether this association varies according to the type of fish.
“The exact biological mechanisms whereby high fish intake reduce risk of depression are not well established.
“It has been proposed that n-3 PUFAs are the beneficial component of fish for the inverse association by changing membrane microstructure and modifying neurotransmission.
“In addition, high-quality protein, vitamins and minerals may have a protective effect on depression.
“Finally, high-fish consumption may also be related to a healthier diet and better nutritional status, which could contribute to the lower risk of depression.
“The specific mechanisms require large experimental studies to confirm.”
The findings were based on 16 articles that included 26 studies and involved 150,278 participants but did not define how much fish should be eaten weekly or how it was prepared.