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 percent 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.
