A new research suggests that consuming a diet which is high in processed food increases the risk of depression.

The University College London team found that people who consumed optimum amount of vegetables, fruit and fish actually had a lower risk of depression.

The British Journal of Psychiatry reported that data on diet among 3,500 middle-aged civil servants was compared with depression five years later.

This was the first study to analyze the UK diet and depression.

The participants were divided into two types of diets. One group ate a diet containing whole foods including fruits, vegetables and fish and the second group mainly ate processed food diet containing desserts, fried food, processed meat, refined grains and high-fat dairy products.

Factors like gender, age, education, physical activity, smoking habits and chronic diseases were taken into account and it was found that there was a significant difference in future depression risk with different diets.

The group consuming whole foods had a 26 percent lower risk of future depression than those who ate processed foods.

People with a diet high in processed food had a 58 percent greater risk of depression than those who ate very few processed foods.

Study author Dr Archana Singh-Manoux said that there is a chance that the finding could be explained by a lifestyle factor that was not taken into consideration.

Margaret Edwards, head of strategy at the mental health charity SANE, said: "Physical and mental health are closely related, so we should not be too surprised by these results, but we hope there will be further research which may help us to understand more fully the relationship between diet and mental health."