People at high risk of MI, stroke and death from cardiovascular (CV) causes may have a recipe for avoiding these events, according to a study published online Feb. 25 in the New England Journal of Medicine. Researchers reported that a Mediterranean diet augmented with extra-virgin olive oil or nuts reduced risk by 30 percent.

Ramón Estruch, MD, of the Hospital Clinic in Barcelona, and colleagues designed the randomized multicenter PREDIMED (Prevención con Dieta Mediterránea) trial to assess if a Mediterranean diet provided preventive benefits to people with no CV disease but who were at high risk of adverse events such as MI and stroke. They enrolled 7,447 people between the ages of 55 and 80 years old who had either type 2 diabetes mellitus or at least three major risk factors. Those included 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.

The primary endpoint was a composite of MI, stroke and CV-related death between 2003 and 2010. Secondary endpoints were stroke, MI, CV-related death and death from any cause.

Participants were randomized to one of three groups: a Mediterranean diet plus extra-virgin olive oil, a Mediterranean diet plus nuts or a low-fat control diet. The Mediterranean diet consisted of olive oil, nuts, fresh fruit, vegetables and cereals and moderate amounts of fish, legumes, white meat and wine. The control diet included low-fat dairy products, starches, fresh fruit, vegetables and lean fish and seafood.  

All participants received quarterly dietary training, but the two Mediterranean diet groups also received personalized advice. Beginning on Oct. 1, 2003, the participants followed their assigned diets; in 2006, researchers amended their study protocol to give the control group personal advice as well. Participants were followed for a median 4.8 years.

The researchers reported good adherence to the two Mediterranean-diet interventions, based on self-reported intake and biomarker analyses. The composite endpoint occurred in 3.8 percent of the Mediterranean diet plus extra-virgin olive oil group, 3.4 percent of the Mediterranean diet plus nuts group and 4.4 percent of the low-fat diet group.

Estruch et al calculated that the rates of the primary endpoint were 8.1, 8, and 11.2 per 1,000 person-years, respectively, for a relative risk reduction of about 30 percent with a Mediterranean diet. The Mediterranean diet groups had a significant reduction in the risk of stroke as well.

“These results support the benefits of the Mediterranean diet for cardiovascular risk reduction,” they wrote. “They are particularly relevant given the challenges of achieving and maintaining weight loss.”

Changes in the study protocol may have biased results showing the benefits of the Mediterranean diet, Estruch et al noted. Also, the study was conducted in Spain and involved only high-risk people, and may not be generalizable to other regions and patient populations. Nonetheless, they concluded that their results showed a high-energy Mediterranean diet offered benefits as a primary prevention for cardiovascular events.