The Seven Countries Study found that Cretan men had exceptionally low death rates from heart disease, despite moderate to high intake of fat. The Cretan diet is similar to other traditional Mediterranean diets, consisting mostly of olive oil, bread, abundant fruit and vegetables, fish, and a moderate amount of dairy foods and wine.
The Lyon Diet Heart Study set out to mimic the Cretan diet, but adopted a pragmatic approach. Realizing that some of the people in the study (all of whom had survived a first heart attack) would be reluctant to move from butter to olive oil, they used a margarine based on rapeseed (canola) oil. The dietary change also included 20% increases in vitamin C rich fruit and bread and decreases in processed and red meat. On this diet, mortality from all causes was reduced by 70%. This study was so successful that the ethics committee decided to stop the study prematurely so that the results of the study could be made available to the public immediately.
According to a study published in the British Medical Journal (May 29, 2008), the traditional Mediterranean diet provides substantial protection against type 2 diabetes. The study involved over 13 000 graduates from the University of Navarra in Spain with no history of diabetes, who were recruited between December 1999 and November 2007, and whose dietary habits and health were subsequently tracked. Participants initially completed a 136-item food frequency questionnaire designed to measure the entire diet. The questionnaire also included questions on the 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 University of Navarra found that participants who stuck closely to the diet had a lower risk of diabetes. A high adherence to the diet was associated with an 83% relative reduction in the risk of developing diabetes.
A study published in The New England Journal of Medicine (July 17, 2008) examined the effects of three diets: low-carb, low-fat, and Mediterranean. The study involved 322 participants and lasted for 2 years. The low-carb and Mediterranean diet resulted in the greatest weight loss, 12 lbs and 10 lbs, respectively. The low-fat diet resulted in a loss of 7 lbs. One caveat of the study is that 86% of the study participants were men. The low-carb and Mediterranean diets produced similar amounts of weight loss in the overall study results and in the men. In the remaining participants who were women, the Mediterranean diet produced 3.8 kg (8.4 lbs) more weight loss on average than the low-carb diet.
A meta-analysis published in the British Medical Journal (September 12, 2008) showed that following strictly the Mediterranean diet reduced the risk of dying from cancer and cardiovascular disease as well as the risk of developing Parkinson's and Alzheimer's disease. The results report 9%, 9%, and 6% reduction in overall, cardiovascular, and cancer mortality respectively. Additionally a 13% reduction in incidence of Parkinson's and Alzheimer's diseases is to be expected provided strict adherence to the diet is observed. As well, a 2007 study found that adherence to the Mediterranean diet (MeDi) may affect not only risk for Alzheimer disease (AD) but also subsequent disease course: Higher adherence to the MeDi is associated with lower mortality in AD. The gradual reduction in mortality risk for higher MeDi adherence tertiles suggests a possible dose-response effect.
A study published in the British Medical Journal (June 23, 2009) showed some components of the Mediterranean diet, such as high vegetable consumption and low meat and meat product consumption, are more significantly associated with low risk of mortality than other components, such as cereal consumption and fish consumption. As part of the European Prospective Investigation into Cancer and Nutrition study, researchers followed more than 23,000 Greek men and women for 8.5 years to see how various aspects of a Mediterranean diet affect mortality. Moderate alcohol consumption, high fruit and nut consumption, and high legume consumption were also associated with lower risk of mortality.