A Japanese-style diet rich in rice, miso soup and fish may help reduce depressive symptoms, according to a new study by the Japan Institute for Health Security.

The research, said to be the first of its kind, suggests that working-age individuals who follow a traditional Japanese diet are less likely to experience depression.

According to Kyodo News, the institute assessed the mental health benefits of a classic Japanese diet comprising soy products, cooked vegetables, mushrooms, fish, seaweed and green tea. A modified version that included fruit, fresh vegetables and dairy products was also examined.

While previous studies have explored links between the Mediterranean diet — which features vegetables, whole grains, olive oil and fish — and mental health, research focusing on the Japanese diet’s impact on depression has been limited, the institute noted.

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“Further research is required, but we hope the evidence shown among Japanese people can be used for public health measures in workplaces and areas concerning the prevention of depression,” it said.

The self-reported survey involved 12,499 employees from five companies, 88 per cent of whom were men with an average age of 42.5 years. Overall, 30.9 per cent of participants showed signs of depressive symptoms, though those who adhered to a Japanese-style diet were less likely to report such symptoms.

The institute said that components of the diet, such as seaweed, soy products and the folic acid in vegetables, may help release neurotransmitters like serotonin and dopamine. Omega-3-rich oily fish also has anti-inflammatory benefits, it added.