The New England Journal of Medicine (NEJM) published online a study from Spain, where they randomly assigned  7447 participants between the age of 55-80, both men and women (57%), who were at high cardiovascular risk, but with no cardiovascular disease at enrollment, to one of three diets: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (adviced to reduce dietary fat). Participants received quarterly individual and group educational sessions and  free provision of extra-virgin olive oil, mixed nuts, or small nonfood gifts. The primary end point was the rate of major cardiovascular events (myocardial infarction, stroke, or death from cardiovascular causes). On the basis of the results of an interim analysis, the trial was stopped after a median follow-up of 4.8 years.

Results: The two Mediterranean-diet groups had good adherence to the intervention, according to self-reported intake and biomarker analyses. A primary end-point event occurred in 288 participants. The multivariable-adjusted hazard ratios were 0.70 (95% confidence interval [CI], 0.54 to 0.92) and 0.72 (95% CI, 0.54 to 0.96) for the group assigned to a Mediterranean diet with extra-virgin olive oil (96 events) and the group assigned to a Mediterranean diet with nuts (83 events), respectively, versus the control group (109 events). No diet-related adverse effects were reported.

Conclusion: Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.

Citation: N Engl J Med 2013. DOI: 10.1056/NEJMoa1200303; This article was published on February 25, 2013, at NEJM.org.

Comments: this study is unique for several reasons: the participants did not have a CVD at the time of enrollment (preventative intervention), large number of women participants (57%), realistic diet that is not punishing (wine is fine), and the end points for the study were true life clinical events, and not laboratory biomarkers. This is a diet that one could adhere without feeling retribution for preventing CVD. The diet in this study, contained: Olive oil: ≥4 tbsp/day, Tree nuts and peanuts: ≥3 servings/wk, Fresh fruits: ≥3 servings/day, Vegetables: ≥2 servings/day, Fish (especially fatty fish), seafood: ≥3 servings/wk, Legumes: ≥3 servings/wk; Sofrito (sauce made with tomato and onion, often including garlic and aromatic herbs, and slowly simmered with olive oil.): ≥2 servings/wk; White meat Instead of red meat; Wine with meals (optionally,)≥7 glasses/wk – Discouraged: Soda drinks: <1 drink/day; Commercial bakery goods, sweets, and pastries:<3 servings/wk, Spread fats: <1 serving/day; Red and processed meats:<1 serving/day. For participants assigned to the Mediterranean diet with nuts, the recommended consumption was one daily serving (30 g, composed of 15 g of walnuts, 7.5 g of almonds, and 7.5 g of hazelnuts). [tbsp.= one table spoon;  United States Department of Agriculture (USDA) sets a serving size for fruit or vegetables to be equal to about one-half cup. Greens like spinach and lettuce have a serving size equal to one full cup. One serving of sliced fruit is equal to one-half cup; however a single piece of fruit, such as an apple or an orange counts as one serving; also note that amount of olive oil above includes oil used for cooking and salads and oil consumed in meals eaten outside the home. In the group assigned to the Mediterranean diet with extra-virgin olive oil, the goal was to consume 50 g (approximately 4 tbsp) or more per day of the polyphenol-rich olive oil – not the refined olive oil!] The results: 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.