Eating a diet high in processed food increases the risk of depression, research suggests. What's more, people who eat lots of vegetables, fruit and fish actually have a lower risk of depression, a University College London team has found.
The team said the study was the first to look at the UK diet and depression, and was also the first to investigate the link between overall diet and mental health, rather than the effects of individual foods. This study adds to a solid body of research linking what we eat and our mental health.
Data on diet among 3,500 middle-aged civil servants was compared with depression five years later, the British Journal of Psychiatry reported.
They split the participants into two types of diet - those who ate a diet largely based on whole foods, which includes lots of fruit, vegetables and fish, and those who ate a mainly processed food diet, such as sweetened desserts, fried food, processed meat, refined grains and high-fat dairy products.
After accounting for factors such as gender, age, education, physical activity, smoking habits and chronic diseases, they found a significant difference in future depression risk with the different diets.
Those who ate the most whole foods had a 26% lower risk of future depression than those who at the least whole foods.
By contrast people with a diet high in processed food had a 58% higher risk of depression than those who ate very few processed foods.
One of the researchers from University College London, said: "There seem to be various aspects of lifestyle such as taking exercise which also matter, but it appears that diet is playing an independent role."
They believe that high levels of antioxidants in fruits and vegetables protect against depression, as does the folate found in broccoli, cabbage, spinach, lentils and chickpeas. However, it is also possible the effect may come from a 'whole food' diet that combines many nutrients from different types of food rather than one single nutrient.
The reverse is also important, because poor eating habits put more of a strain on the body. A diet that is high in foods that make blood sugar levels go up and down, such as junk food which is refined, processed, and high in sugar and fats, can have detrimental effects on blood vessels and on the brain.
Research paper details:
Akbaraly TN, Brunner EJ, Ferrie JE, et al. Dietary pattern and depressive symptoms in middle age. The British Journal of Psychiatry, Nov 2009; 195: 408 - 413.