The study, to appear in the New England Journal of Medicine, involved 7,447 individuals (55-80 years old) at high risk of cardiovascular disease but with no symptoms.
The results favor two Mediterranean diets (one supplemented with nuts, the other with virgin olive oil) over a low-fat diet for beneficial effects on intermediate outcomes that include body weight, blood pressure, insulin resistance, blood lipids, lipid oxidation and systemic inflammation.
The study, called “PREDIMED” for “PREvención con Dieta MEDiterránea” (Prevention with Mediterranean Diet) began in 2003 and was completed in 2011. Participants were followed for an average of 4.8 years.
“The aim of PREDIMED was to determine whether a plant-based Mediterranean diet, supplemented with either tree nuts such as walnuts, almonds and hazelnuts or virgin olive oil, when compared to a low-fat diet, can help prevent cardiovascular diseases such as cardiovascular death, heart attack and stroke,” said Dr. Miguel Angel Martinez of the University of Navarra, Spain, a lead investigator of the study, which was released simultaneously in Loma Linda and Spain.
“What we found was that a Mediterranean diet offers a preventive efficacy that was also assessed on secondary variables, including death from all causes, and incidence of diabetes and metabolic syndrome,” added Martinez, a physician, epidemiologist and nutrition researcher.
The Mediterranean diet is a pattern of eating similar to the traditional dietary habits of people living in the countries bordering the Mediterranean Sea. This includes fresh fruits and vegetables, seafood, whole grains and nutritious fats, including walnuts and olive oil.
PREDIMED is a parallel group, multi-center, single-blind, randomized clinical trial conducted by 16 research groups in seven communities in Spain. Participants were given dietetic support and quarterly education sessions to ensure compliance. Energy intake was not specifically restricted in any intervention group. Participants were randomly assigned to one of three groups:
- Low-fat diet (control group)
- Mediterranean diet supplemented with virgin olive oil (50 ml per day); or
- Mediterranean diet supplemented with 30 g mixed nuts per day (15 g walnuts, 7.5 g almonds and 7.5 g hazelnuts).
“This study is a prime example of the type of international research being shared at this conference of 800 academics, researchers, dieticians and others dedicated to advancing research about the benefits of plant-based diets,” said Dr. Joan Sabaté, chair of the International Congress on Vegetarian Nutrition and chair of the Department of Nutrition at Loma Linda University’s School of Public Health.
Sabaté served as principal investigator in a nutrition research study that directly linked the consumption of walnuts to significant reductions in serum cholesterol. His findings were published in the New England Journal of Medicine in 1993.
“Twenty years ago we released a study showing the health benefits of nuts,” Sabaté said. “Now, the results of a trial, also released at Loma Linda, further demonstrate that a plant-based diet, infused with nutritious unrefined plant fats, can have long-lasting effects for heart health and a productive and a productive life.”
The Congress on Vegetarian Nutrition, held every five years, also features the release of research on such topics as the link between diet and longevity, reducing the risk of osteoporosis and how vegetarian diets can reduce weight.
For details, please visit www.predimed.org or www.walnuts.org/med-diet.
Complete information on the Congress, including abstracts of the presentations, can be found at www.VegetarianNutrition.org.