Mediterranean Diet for CV Protection

Loma Linda, CA — A Mediterranean diet supplemented with either extra virgin olive oil or mixed nuts may cut the risk of cardiovascular events by as much as 30% in subjects at high risk of developing heart disease, as compared with people advised to eat a reduced-fat diet [1].

Those are the key findings from the randomized controlled PREDIMED primary-prevention trial presented here at the International Congress on Vegetarian Nutrition.

The Mediterranean diet already reigns supreme in secondary prevention of CV events. PREDIMED, which looked at diet effects on hard clinical end points, carves out an important role for this dietary eating pattern in primary prevention.

“These results support the benefits of the Mediterranean diet for CV risk reduction [and] are particularly relevant given the challenges of achieving and maintaining weight loss,” investigators write in a paper published in advance of the presentation in the New England Journal of Medicine. PREDIMED was led by Dr Ramón Estruch (Hospital Clinic, Barcelona, Spain) and Dr Miguel Angel Martínez-González (Clinical Universidad de Navaraa, Pamplona, Spain).

Commenting on the study for heartwire , Dr Marc Gillinov (Cleveland Clinic, OH), who was not involved in the study, pointed out that there are very few studies of any diets that are rigorously designed and that address hard clinical outcomes. “This randomized controlled trial is by far the best in class when it comes to dietary studies. We should take its results seriously: if you have risk factors for cardiovascular disease–and the majority of adult Americans do–your best bet is to follow a Mediterranean diet.”

PREDIMED: Oil and Nuts Over Fat Restriction

PREDIMED enrolled 7447 men and women ranging in age from 55 to 80 years, none of whom had established cardiovascular disease but who were at high CV risk. Subjects were randomized to one of two Mediterranean diet groups (one supplemented with olive oil, the other with nuts) or to a control diet wherein subjects were advised to try to reduce dietary fat.

Patients in the Mediterranean-diet groups were invited to regular dietary training sessions; by contrast, those in the control group were, for the first three years, sent leaflets explaining a low-fat diet. After a protocol amendment at the three-year mark, low-fat-diet patients were also invited to regular group sessions and offered personalized advice at the same level of intensity as the Mediterranean groups.

The study was stopped when an interim analysis at 4.8 years revealed a clear signal of benefit among subjects eating the Mediterranean diets. In the olive-oil and mixed-nut Mediterranean diet groups, the primary end point (MI, stroke, or CV death) was reduced by 30% and 28% respectively, as compared with the control group.

Study dropouts, meanwhile, were twice as common in the control diet group as in the Mediterranean diet group (11.3% vs 4.9%). “Favorable trends” were seen for both stroke and MI rates among subjects eating the Mediterranean diet, but numbers were too low to be relevant statistically. A total of 288 subjects experienced an event in the study: 96 events in the olive-oil group, 83 in the nut group, and 109 in the control group.

Of special note, subjects randomized to the Mediterranean diets were not told to reduce calories, a major barrier to success in many dietary interventions, particularly the long-supported “low-fat” approach.

Good Fat and Bad

In an email to heartwire , Estruch highlighted the importance of differentiating between different types of fat “Animal fat should be avoided,” he said, whereas “vegetal fats–extra virgin olive oil and nuts–should be recommended [within] a healthy food pattern such as the Mediterranean diet.”

Asked whether the findings would be applicable to other parts of the world where saturated fats are such a common component of everyday eating, Estruch stressed the importance of education.

“People should know that the Mediterranean diet is a diet healthier than others and should know the key components of this food pattern. The plan should be to increase the intake of the key foods (vegetables, fruit, nuts, fish, legumes, extra virgin olive oil, and red wine in moderation), also increase the intake of white meat, and decrease the intake of red and processed meat, soda drinks, whole dairy products, commercial bakery goods, and sweets and pastries.”

He continued: “To achieve a score of 14 in the 14-item adherence scale to traditional Mediterranean diet [laid out in a supplemental appendix in the paper] is more or less impossible, but to upgrade two to three points in this score is enough to reduce your cardiovascular risk by 30%.”

Gillinov, in turn, pointed out that there are no data of a similar quality supporting a low-fat diet, although these have long been promoted by physicians and professional medical groups. “The Mediterranean diet contains moderate quantities of fat, and it clearly wins in this trial of primary prevention,” he said.

Dr Steven Nissen , also of the Cleveland Clinic, was even more effusive, calling PREDIMED “a spectacular study that was extremely difficult to perform.”

“The findings are compelling and should alter the dietary advice we give patients. The currently popular ultralow-fat diets . . . are clearly not best for patients,” he told heartwire in an email. “The standard AHA-recommended diet should be modified to reflect these findings: fat is not the problem with the American diet, we just eat the wrong types of fats.”