Traditional Mediterranean diet, rich in olive oil, grains, fruits, nuts, fish and vegetables, protects against type 2 diabetes, according to a study.

The study involved over 13,000 graduates from the University of Navarra in Spain with no history of diabetes, between December 1999 and November 2007. Their dietary habits and health were subsequently tracked.

Participants initially completed a 136-item food frequency questionnaire designed to measure the entire diet including those on use of fats and oils, cooking methods and dietary supplements.

Every two years participants were sent follow-up questionnaires on diet, lifestyle, risk factors, and medical conditions. New cases of diabetes were confirmed through medical reports.

During the follow-up period (median 4.4 years), the researchers from the same university found participants who stuck closely to the diet had a lower risk of diabetes.

A high adherence to the diet was associated with an 83 percent relative reduction in the risk of developing diabetes.

Interestingly, those participants who stuck strictly to the diet also had the highest prevalence of risk factors for diabetes such as older age, a family history of diabetes, and a higher proportion of ex-smokers.

The major protective characteristics of the diet include a high intake of fibre and vegetable fat, a low intake of trans-fatty acids, and a moderate intake of alcohol.

In addition, a key element of the diet is the abundant use of virgin oil for cooking, frying, spreading on bread, and dressing salads. The authors conclude by calling for larger trials to confirm their findings.

These findings have been published on British Medical Journal website.