The researchers suggest the reduced risk of depression observed in their analysis could be due to the fatty acids, proteins, vitamins and minerals that fish contain.
The meta-analysis, published in the Journal of Epidemiology & Community Health, looked at data from relevant studies published between 2001 and 2014.
"Higher fish consumption may be beneficial in the primary prevention of depression," the authors write. "Future studies are needed to further investigate whether this association varies according to the type of fish."
Depression affects an estimated 350 million people worldwide, making it the world's leading cause of disability. As things stand, it is also projected to become the world's second leading cause of disease burden by 2020.
Unfortunately, current forms of treatment for the condition are considered to be unsatisfactory on account of poor compliance rates and numerous potential side effects. Consequently, many researchers are interested in assessing lifestyle factors that could influence the risk of depression.
One such lifestyle factor is diet. Many previous studies have indicated that food consumption may be related to the risk of depression. One recent meta-analysis found that following a healthy diet was associated with a reduced risk of the disorder, the authors note, although this could not separate the influence of different dietary components, such as fruit, vegetables or fish.
Over the past year, Medical News Today has reported on a number of studies that have found health benefits for fish consumption. Last month, a study revealed that the omega-3 fatty acids found in fish oil could reduce the risk of psychosis. In February, another study suggested that collagen from tilapia fish could help wounds heal faster.
High fish consumption linked to 17% reduced risk of depression
For their review, the researchers identified 16 suitable articles that were eligible for inclusion, incorporating data from 26 studies and a total of 150,278 participants. Of these studies, 10 involved participants in Europe and seven involved participants in North America. The remainder involved participants in Asia, Oceania and South America.
- Major depression is one of the most common mental disorders in the US
- Around 6.7% adults in the US experience major depression each year
- Depression is likely caused by a combination of genetic, psychological, biological and environmental factors.
The researchers found that in the European studies, there was a significant association between high consumption of fish and a 17% reduced risk of depression compared with the lowest levels of fish consumption. Although they observed this association in both cohort and cross-sectional studies, it did not emerge in studies from other continents.
When examining the effects of fish consumption on men and women separately, the researchers found that this association remained, with a 20% reduced risk in men and 16% reduced risk in women.
Differences in fish type, fish preservation and cooking styles could be a determining factor in the inconsistencies observed between different studies, the researchers suggest.
Despite the association only being found in the European studies, the researchers conclude that their review shows that higher fish consumption is significantly associated with reduced risk of depression. They also suggest that there could be a biological explanation for this association.
Omega-3 fatty acids found in fish oil could change the structure of brain membranes and alter levels of dopamine and serotonin in the body - two neurotransmitters that are believed to play a role in depression.
"In addition, high-quality protein, vitamins and minerals may have a protective effect on depression," the authors add.
Omega-3 fatty acids are frequently heralded for their healthful properties. However, in a recent study reported by MNT, omega-3 supplements failed to demonstrate any effect against cognitive decline. This finding is significant as some previous studies have suggested that omega-3 may have a protective role in maintaining cognitive function.