Following a Mediterranean diet could help prevent depression, new research suggests.
Eating plenty of fruit, vegetables, nuts, plant-based food and fish may cut the risk of developing the condition by around a third, according to a study published in the Molecular Psychiatry journal.
Meanwhile, a diet high in saturated fat, sugar and processed food was associated with an increased likelihood of depression.
Lead author Dr Camille Lassale, from the department of epidemiology and public health at UCL, London, said: "There is compelling evidence to show that there is a relationship between the quality of your diet and your mental health.
"This relationship goes beyond the effect of diet on your body size or other aspects of health that can in turn affect your mood.
"We aggregated results from a large number of studies and there is a clear pattern that following a healthier, plant-rich, anti-inflammatory diet can help in the prevention of depression."
The researchers analysed data from 41 studies, including four which examined the link between a traditional Mediterranean diet and mental health among 36,556 adults.
People who most closely adhered to a Mediterranean diet had a 33% lower risk of developing depression over the next eight to 12 years, they found, compared to those whose diet least resembled it.
Five of the studies looked at the impact of an inflammatory foods diet on mental health in 32,908 adults across the world.
A diet low in saturated fat, sugar and processed food was linked with a 24% reduced risk of developing depression over the next five to 12 years.
Dr Lassale said: "A pro-inflammatory diet can induce systemic inflammation, and this can directly increase the risk for depression.
"There is also emerging evidence that shows that the relationship between the gut and brain plays a key role in mental health and that this axis is modulated by gastrointestinal bacteria, which can be modified by our diet."
The results mean "there are now strong arguments" for diet to be considered as part of the treatment of mental health, co-author Tasnime Akbaraly said.
She added: "Our study findings support routine dietary counselling as part of a doctor's office visit, especially with mental health practitioners.
"This is of importance at a patient's level, but also at public health level, especially in a context where poor diet is now recognised to be the leading cause of early death across middle and high-income countries and at the same time mental disorders as the leading cause of disability."