Previous research has shown that a diet rich in oily fish, olive oil and fresh fruit and vegetables can help to protect against heart disease.
This latest study involved 10,094 healthy people living in Spain who completed a dietary questionnaire between 1999 and 2005.
Researchers used the answers to calculate adherence to a Mediterranean diet. This was assessed on the basis of nine components, including intake of alcohol, dairy products and monounsaturated acids.
Overall, 480 new cases of depression were identified. Those who followed the Mediterranean diet most closely had a 30 per cent lower risk of depression than those who had the lowest Mediterranean diet scores.
What is it about the diet that prevents depression?
The researchers, led by Dr Almudena Sanchez-Villegas, of the University of Las Palmas de Canaria, said that components of the diet may improve blood vessel function, fight inflammation, reduce risk for heart disease and repair cell damage.
'However, the role of the overall dietary pattern may be more important than the effect of single components,' the researchers said.
'The synergistic combination of a sufficient provision of omega-3 fatty acids together with other natural unsaturated fatty acids and antioxidants from olive oil and nuts may exert a fair degree of protection against depression,' they added.
What do other researchers say?
Dr Andrew McCulloch, chief executive of the Mental Health Foundation, told GP: 'This is an exciting piece of research. The body of evidence linking food to mood and behaviour has been growing for years.
'As is the case with any organ in the body, the brain is sensitive to the food we eat. While claims for superfoods and wonder diets should be treated with caution, a balanced diet, particularly if rich in omega-3 oils, is a great way to look after your mental health.'
The use of diet to help treat specific mental health problems has enormous potential and urgently requires further research, he added.
- Eating a Mediterranean diet could reduce the risk of depression by 30 per cent.
- High levels of omega-3, antioxidants and vitamins in the diet are believed to reduce depression risk.
- GPs should encourage patients to follow the Mediterranean diet as it is also beneficial for the heart.