Mediterranean Diet ‘can reduce heart attacks in people at higher risk’

A Mediterranean diet rich in olive oil, nuts, seafood, whole grains, and vegetables has been linked to various benefits for healthy people. Now, a global review of evidence suggests that such a diet can lower the risk of a heart attack, stroke or early death for hundreds of millions of people with an increased risk of cardiovascular disease.

Limited Evidence for Those at Higher Risk of Cardiovascular Disease

Those at increased risk of cardiovascular disease include hundreds of millions of people who live with obesity, type 2 diabetes, high blood pressure, high cholesterol, physical inactivity, smoking, or harmful levels of alcohol. Guidelines currently recommend various diets for such people, but they typically rely on low-certainty evidence from non-randomised studies. Until now, there has been limited evidence of how a Mediterranean diet might help those at increased risk of cardiovascular disease.

Study and Analysis

The first comparative review of seven programs has now been published in the BMJ journal. Researchers from the US, Canada, China, Spain, Colombia, and Brazil reviewed 40 randomised controlled trials involving more than 35,000 people.

The study analysed seven diets: Mediterranean, low fat, very low fat, modified fat, combined low fat and low sodium, Ornish (a vegetarian diet, low in fat and refined sugar), and Pritikin (a low-fat, high-fiber diet, limiting processed food and red meat). The participants were followed for an average of three years across the seven diet programs.

Key Findings

Based on moderate-certainty evidence, Mediterranean diet programs were better than minimal intervention at preventing all-cause mortality, non-fatal heart attack, and stroke in people at risk of cardiovascular disease. Low-fat programs were also superior to minimal intervention, with moderate certainty, to prevent all-cause mortality and non-fatal heart attack. The five other dietary programs generally had little or no benefit compared with minimal intervention, typically based on low- to moderate-certainty evidence.

Limitations

The researchers acknowledged several limitations to their work, such as being unable to measure adherence to diet programs and the possibility that some of the benefits may have been due to other elements within the programs, such as drug treatments and support to stop smoking.