People who often eat fish, including so-called blue-backed fish such as saury, face a lower risk of suffering depression than those consuming less, a team of researchers from institutes including Japan’s National Cancer Center has said.

In its research findings that were announced in a U.S. medical magazine, the team said that n-3 fatty acids, which have various effect, including anti-inflammatory action, are in blue-backed and other fish and that the substances are believed to contribute to lower risks of depression.

In Japan, saury, mackerel, sardine and other fish are called blue-backed fish, or aozakana, because of the blue color on their backs.

The research covered 1,181 men and women aged between 40 and 59 in Nagano Prefecture. Between 1990 and 2015, the team tracked how much blue-backed and other fish the participants ate and checked if they were depressed in 2014-2015.

The research participants were divided into four groups according to fish consumption. The groups’ average daily intake of fish came to 57 grams, 84 grams, 111 grams and 153 grams, respectively.

The risk of depression for the group with the highest consumption was 56 percent lower than that for the group with the lowest intake.

The two other groups showed no statistically significant differences in terms of depression risk. Still, the risk was lower for the two groups than for the group with the lowest fish consumption.

Based on the estimated intake of n-3 fatty acids, such as eicosapentaenoic acid and docosapentaenoic acid, from the participants’ fish consumption, the team also confirmed that groups ingesting appropriate amounts of such substances are less likely to suffer depression.

“Slightly less than a fish a day will do if it’s saury,” said Yutaka Matsuoka, a member of the team and head of the Health Care Research Division at the center center’s Quality of Life Research Group.

People can make up for their insufficient fish intake with processed or canned foods and nutritional supplements, Matsuoka added.

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