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Jul 13, 2018

Study Confirms the Heart-Health Benefits of a Mediterranean Diet

A second analysis reconfirms the results of a Spanish study demonstrating that a Mediterranean diet including olive oil and nuts can reduce heart risks. 

Despite flaws in a 2013 study testing the heart-health benefits of a Mediterranean diet, a second analysis confirms that a Mediterranean diet rich in olive oil or nuts reduces risk of heart events compared to a low-fat diet. Findings were recently published in the New England Journal of Medicine and highlight the potential benefits of a Mediterranean diet for adults at high risk for heart disease.

Known as the PREDIMED trial (Prevencion con Dieta Mediterranea), this study tested the impact of two Mediterranean diets on cardiovascular risk. The first included a Mediterranean diet plus 30 grams of mixed nuts per day, including a combination of walnuts, hazelnuts and almonds. The second was a Mediterranean diet plus at least 4 tablespoons a day of extra-virgin olive oil. These diets were compared to a low-fat diet, which discouraged consumption of any high-fat items such as oil, meats and nuts.

Many studies suggest that a Mediterranean diet, which is rich in healthy fats, fish and includes wine with meals, helps protect heart health. And the PREDIMED study was designed to test the effects of a Mediterranean diet plus olive oil or nuts compared to a low-fat diet.

The study was conducted at 11 study sites in Spain and included 7,447 adults who were free of heart disease but had high cardiovascular risk. Participants were between 55 and 80 years of age at the start of the study and randomly assigned to one of the three diets for roughly five years.

Results of the study were initially published in 2013, showing that the Mediterranean diet significantly reduced risk of heart attack, stroke and heart-related death compared to the low-fat diet. However, researchers discovered flaws with the way the study was carried out and had to withdraw those findings. The biggest issue was that not all participants were randomly assigned to their diet, which may have influenced results.

Fortunately, researchers were able to re-analyze the data, accounting for this issue. They found that the Mediterranean diet plus olive oil or nuts reduced risk for heart events by roughly 30% compared to a low-fat diet. This number was similar to initial findings that were published in 2013.

While retraction of initial results was disappointing, experts are encouraged by the new findings. Findings reconfirm the heart-health benefits of a Mediterranean diet, particularly in adults at high risk for heart disease. They also suggest that the Mediterranean diet may be more effective at preventing heart disease than a low-fat diet, which has been popular in the United States.

But when it comes to a healthy diet, experts note that it’s also important to find one that we can stick with. If it’s difficult to adhere to all components of a Mediterranean diet, experts recommend incorporating a few aspects that are easier to maintain—like eating nuts or increasing fish intake. As experts explain, even small changes in a diet can have significant health benefits when maintained over time.

Questions for You to Consider

  • What is the Mediterranean diet?
  • The Mediterranean diet is a way of eating rather than a formal diet plan. It features foods eaten in Greece, Spain, southern Italy and France, and other countries that border the Mediterranean Sea.

    The Mediterranean diet emphasizes eating foods like fish, fruits, vegetables, beans, high-fiber breads and whole grains, and olive oil. Meat, cheese, and sweets are very limited. The recommended foods are rich with monounsaturated fats, fiber, and omega-3 fatty acids.

    The Mediterranean diet is like other heart-healthy diets in that it recommends eating plenty of fruits, vegetables, and high-fiber grains. But in the Mediterranean diet, an average of 35-to-40% of calories can come from fat. Most other heart-healthy guidelines recommend getting less than 35% of your calories from fat. The fats allowed in the Mediterranean diet are mainly from unsaturated oils, such as fish oils, olive oil, and certain nut or seed oils (such as canola, soybean, or flaxseed oil). These types of oils may have a protective effect on the heart.  For more information, read this overview of the Mediterranean diet.
  • How can I prevent heart disease?

  • The best ways to help prevent heart disease is by eating a healthy diet, staying physically active, quitting smoking (if a current smoker) and maintaining a healthy weight. Patients should also know their numbers, including blood pressure, cholesterol and glucose, which are important to heart health.

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