Published online by the New England Journal of Medicine, findings from the landmark Spanish PREDIMED (PREvención con DIeta MEDiterranea) trial, report that a Mediterranean diet including nuts, primarily walnuts, reduced the risk of cardiovascular diseases (myocardial infarction, stroke or cardiovascular death) by 30% and specifically reduced the risk of stroke by 49% when compared to a reference diet consisting of advice on a low-fat diet (American Heart Association guidelines).
As one of the world’s largest and longest dietary intervention studies, PREDIMED is a multicenter, randomized, primary prevention trial of cardiovascular disease funded by the Spanish Ministry of Health.
These findings are significant considering that heart disease is the leading cause of death for both men and women in the United States.
In addition to being the first and third leading causes of death in America, heart disease and stroke result in serious illness and disability, decreased quality of life, and hundreds of billions of dollars in economic loss every year.
According to lead researcher Dr. Ramon Estruch, “The results of the PREDIMED trial are of utmost importance because they convincingly demonstrate that a high vegetable fat dietary pattern is superior to a low-fat diet for cardiovascular prevention.”
Co-investigator Dr. Emilio Ros believes that the unique nutrient profile of walnuts may be a key factor responsible for the benefits reported in the PREDIMED study.
“In addition to being the only nut containing significant amounts of alpha-linolenic acid – the plant-based omega-3 fatty acid – walnuts offer numerous antioxidants and additional nutrients that, I believe, work together synergistically to produce their cardiovascular protective effect,” states Dr. Ros.
The trial included 7,447 individuals (55-80 years old) at high cardiovascular risk who were followed for an average of 4.8 years. Participants were randomized into one of three intervention diets: Low-fat diet (control group), Mediterranean diet supplemented with extra-virgin olive oil (50 ml per day), or a Mediterranean diet supplemented with 30 g mixed nuts, primarily walnuts, per day (15 g walnuts, 7.5 g almonds and 7.5 g hazelnuts).
In addition to the benefits of the Mediterranean diet supplemented with nuts, the research found that the Mediterranean diet enriched with extra-virgin olive oil also reduced the risk of cardiovascular diseases by 30%.
Cardiologist Dr. James Beckerman believes the results of PREDIMED showcase the importance of taking preventive dietary measures to protect the heart.
“Extensive research has found walnuts to help reduce cholesterol, decrease inflammation and improve endothelial function. These new results provide further evidence for encouraging people to adopt a Mediterranean diet including walnuts,” states Dr. Beckerman.
The PREDIMED trial was financed entirely with public funds from Instituto de Salud Carlos III in Madrid, Spain, through the research networks CIBER Fisiopatologia de la Obesidad y Nutricion and RTIC 06/0045.
The study has had continuous support and advice from key investigators in Columbia, Harvard, and Loma Linda universities and the EPIC-Spain study. Supplemental foods were donated, including extra-virgin olive oil (by Hojiblanca and Patrimonio Comunal Olivarero, both in Spain), walnuts (by the California Walnut Commission), almonds (by Borges, in Spain), and hazelnuts (by La Morella Nuts, in Spain).
None of the sponsors had any role in the trial design, data analysis, or reporting of the results.