A traditional Mediterranean diet is characterized by a high intake of olive oil, fruits, nuts, vegetables and cereals; a moderate intake of fish and poultry, a low intake of red meat, processed meats, dairy products, and sweets. Wine in moderation is consumed with meals. The New England Journal of Medicine recently published a study done in Spain that was a randomized control trial looking at the Mediterranean diet pattern for the primary prevention of cardiovascular events (heart attack and stroke).
Previous observational studies, secondary prevention studies and systematic reviews have all found the Mediterranean Diet as the most likely dietary model to provide protection against coronary heart disease.
The PREDIMED trial ran from October 2003 through June 2009 and a total of 7,447 people were randomly assigned to one of three diet study groups: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts (walnuts, almonds and hazelnuts), or a control diet which consisted of advice to reduce dietary fat intake. Eligible participants were men aged 55 to 80 years old and women aged 60 to 80 years old with no cardiovascular disease at enrollment, but who were at high risk for developing cardiovascular disease because they either had type 2 diabetes mellitus or at least three of the following major risk factors: smoking, hypertension, elevated low-density lipoprotein cholesterol levels, low high-density lipoprotein cholesterol levels, overweight or obesity, or a family history of premature coronary heart disease. No total calorie restriction was advised, nor was physical activity promoted.
On the basis of the results of an analysis done at 4.8 years the study was stopped early due to positive results. During this time a total of 288 primary-outcome events of stroke or heart attack or death from cardiovascular causes occurred. Of these total events, 96 occurred in the group assigned to a Mediterranean diet with extra-virgin olive oil (3.8%), 83 occurred in the group assigned to a Mediterranean diet with nuts (3.4%), and 109 occurred in the control group (4.4%). The overall conclusion of this study was that a 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 NEJM article about this study also stated that the results of this study compared favorably with the Women’s Health Initiative Dietary Modification Trial, wherein a low-fat dietary approach resulted in no cardiovascular benefit. But, components of the Mediterranean diet reportedly associated with better survival included moderate consumption of wine, low consumption of meat and meat products, and high consumption of vegetables, fruits, nuts, legumes, fish and olive oil.