Commentary

de Lorgeril et al provided good clinical control in the examination of their hypotheses that a Mediterranean diet would have both cardioprotective and cancer reduction effects. For example, they used annual follow up visits with a dietitian, did 3 day diet recall histories, and took blood samples to see if patients really used the diet advice. Both diets consisted of approximately 30% of calories from total fat, but differed in the type of fat consumed (eg, for the Mediterranean diet, fat was provided by canola margarine). The results add to the diet-disease debate that type of dietary fat contributes to morbidity and mortality over and above the effects of total fat intake alone.

Because the researchers did a good job of examining alternative reasons for their findings, I am convinced that it is prudent to advise patients that a Mediterranean diet would most likely be of help to them. Specifically, this means increasing carbohydrates, fruits and vegetables (5 servings/d), reducing meats, allowing moderate use of red wine with dinner, and using canola and olive oil exclusively, and no butter or cream.

Because the sample was primarily men, the generalisability of the results to women cannot be assumed. The authors also did not describe the racial distribution of the sample. It is unclear whether all components of the Mediterranean diet need to be adopted to have the protective effects. For example, could people just switch to canola and olive oil or just consume a greater variety of fruits and vegetables, or do they really need to add red wine to their diet? Perhaps it is an interaction of all of these factors.

It was particularly interesting that patients with cancer had lower concentrations of trans-fatty acids and had not used lipid lowering drugs. Given that trans-fatty acids (which are formed during hydrogenation of oils into margarine) were associated with 6% of acute MIs in Italian women,¹ additional research should be done on this important topic.