Cardiovascular Disease and a Mediterranean Diet

Posted by • April 5th, 2013

In a randomized trial, participants assigned to a Mediterranean diet supplemented with either nuts or extra-virgin olive oil had a significantly lower rate of cardiovascular events at 4.8 years than participants assigned to a low-fat control diet.

A systematic review ranked the Mediterranean diet as the most likely dietary model to provide protection against coronary heart disease. Small clinical trials have uncovered plausible biologic mechanisms to explain the salutary effects of this food pattern. We designed a randomized trial to test the efficacy of two Mediterranean diets (one supplemented with extra-virgin olive oil and another with nuts), as compared with a control diet (advice on a low-fat diet), on primary cardiovascular prevention.

Clinical Pearls

•  What are the characteristics of a traditional Mediterranean diet?

The traditional Mediterranean diet is characterized by a high intake of olive oil, fruit, nuts, vegetables, and cereals; a moderate intake of fish and poultry; a low intake of dairy products, red meat, processed meats, and sweets; and wine in moderation, consumed with meals.

•  What were the primary results in this study, which evaluated the magnitude of reduction in cardiac risk due to the Mediterranean diet supplemented with either extra-virgin olive oil or nuts in a high-risk population?

In this trial, an energy-unrestricted Mediterranean diet supplemented with either extra-virgin olive oil or nuts resulted in an absolute risk reduction of approximately 3 major cardiovascular events per 1000 person-years, for a relative risk reduction of approximately 30%, among high-risk persons who were initially free of cardiovascular disease. The median follow-up period was 4.8 years. A total of 288 primary-outcome events occurred: 96 in the group assigned to a Mediterranean diet with extra-virgin olive oil (3.8%), 83 in the group assigned to a Mediterranean diet with nuts (3.4%), and 109 in the control group (4.4%).

Table 3. Outcomes According to Study Group.

Morning Report Questions

Q: Which individual components of the primary endpoint differed between study and control groups?

A: The results of multivariate analyses showed a similar protective effect of the two Mediterranean diets versus the control diet with respect to the primary end point, which was a composite of myocardial infarction, stroke, and death from cardiovascular causes. Regarding components of the primary end point, only the comparisons of stroke risk reached statistical significance. The risk of stroke was reduced significantly in the two Mediterranean-diet groups. This is consistent with epidemiologic studies that showed an inverse association between the Mediterranean diet or olive oil consumption and incident stroke.

Q: What do the authors propose as the dietary components that most likely were responsible for the observed benefits?

A: Salient components of the Mediterranean diet reportedly associated with better survival include moderate consumption of ethanol (mostly from wine), low consumption of meat and meat products, and high consumption of vegetables, fruits, nuts, legumes, fish, and olive oil. The interventions were intended to improve the overall dietary pattern, but the major between-group differences involved the supplemental items. Thus, extra-virgin olive oil and nuts were probably responsible for most of the observed benefits of the Mediterranean diets. Differences were also observed for fish and legumes but not for other food groups.

One Response to “Cardiovascular Disease and a Mediterranean Diet”

  1. […] Another recent study in the New England Journal of Medicine found that eating a traditional Mediterranean diet including “healthy” fats such as nuts or extra-virgin olive oil was associated with a significantly lower risk of death from heart disease. […]