People who eat a lot of fish and other seafood are half as likely to develop depression, an epidemiological study conducted by a National Cancer Center Japan and Keio University has found.
The high levels of omega-3 fatty acids contained in blue-backed fish varieties are thought to act in preventing the disease. The research team's results were published in the online American medical journal "Translational Psychiatry" on Sept. 27.
The research team traced the lifestyles of 1,181 residents of the Minamisaku district of Nagano Prefecture, who were aged between 40 and 59 in 1990, for 25 years beginning in that year. The team looked at the subjects' consumption of 19 different types of fish and other seafood and if there was a connection with the onset of depression.
The participants were divided into four groups depending on their daily consumption, and when compared to the group with the lowest median intake of 57 grams, the group that ate the second-most amount of fish and other seafood at a median of 111 grams was 56 percent less likely to develop depression. The group that ate the most seafood was only 26 percent less likely, but the team believes this was due to influence from other factors, such as how the fish was prepared and different foods eaten by those participants.
Additionally, when the subjects' consumption of fatty acids was calculated, there was a trend for the risk to be lower if the person also had high levels of eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA), which are categorized as types of omega-3 fatty acids.
Omega-3 fatty acids are thought to aid in synthesizing substances related to the transmission of information in the brain, as well as increase the amount of substances that act as nourishment for the nervous system. National Cancer Center Japan Division of Health Care Research chief Yutaka Matsuoka said, "I hope the results will change how people look at the benefits of a fish diet."