Olive Oil and Nuts Help Mediterranean Diet Shine

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Researchers working together at medical schools, hospitals, and universities throughout Spain have taken an innovative look at the Mediterranean Diet and its ability to lower risk of metabolic syndrome (MetS). After following more than 1,200 participants for a full year, these investigators found that a Mediterranean Diet—when supplemented with additional amounts of either nuts or olive oil—decreased the presence of metabolic syndrome in the study participants better than low-fat diet advice. The details of this study are fascinating, because they give us such a unique look at the role of high-quality fats in a healthy diet. One factor that makes a Mediterranean Diet approach to health very different is its inclusion of certain high-fat foods. These foods include olive oil (which is almost 100% fat), nuts (which are usually 80-90% fat), and fish like salmon (which are often about 40% fat).

High-fat foods have often been discouraged in dietary recommendations for persons wanting to lower their risk of disease, especially cardiovascular disease. The researchers in this study placed the spotlight squarely on this high-fat issue by giving one group of participants instruction on a low-fat diet in which high-fat foods were discouraged, and instructing two other groups on a Mediterranean Diet with either (1) one liter of added virgin olive oil per week or (2) an added ounce of mixed nuts per day. The mixed nuts were divided into 50% walnuts, 25% almonds, and 25% hazelnuts. Since an ounce of nuts could add about 20 grams of fat to the daily diet, and the weekly liter of olive oil could add far greater amounts of daily fat, both of these groups were likely to get far more dietary fat than the group on a low-fat diet. But it is important to note that these higher-fat groups were only getting high-quality plant fats from their added nuts or olive oil. (The nuts and extra virgin olive oil included among the World’s Healthiest foods have higher quality fat than many animal foods or processed foods because they have greater amounts of polyunsaturated and monounsaturated fat, and in some cases, important amounts of omega-3 fats).

Metabolic syndrome (MetS) affected about 2/3rds of all participants at the start of the study. (Met S is a collection of risk factors for heart disease and diabetes that includes high blood pressure, high triglyceride levels in the blood, low HDL cholesterol in the blood, high fasting blood sugar levels, and above average waist circumference). After one year in the study, the number of people affected by MetS was reduced by 2% in the low-fat diet group, 6.7% in the Mediterranean diet plus olive oil group, and 13.7% in the Mediterranean diet plus nuts group! In other words, the increased presence of high-quality fats in the diet, coupled with a Mediterranean Diet approach did much more to lower the risk of heart disease than a low-fat approach which avoided these foods.

We’re fairly certain that the researchers in this study did not intend for any one participant to single-handedly consume a full liter of olive oil per week. (One liter per week would mean about 4.75 ounces per day, or more than 125 grams of added daily fat). The liter bottles of virgin olive oil were most likely a way of conveniently providing olive oil to participants and making sure that participants had easy access to this World’s Healthiest food in their daily diet. The researchers did not measure the exact amount of olive oil consumed, but it is reasonable to think that participants enjoyed olive oil in a fairly unrestricted way in their diets.

We take this same basic approach in our Healthiest Way of Eating Plan, in which we don’t go overboard on the amount of olive oil, but incorporate it daily and in a way that is fully enjoyable and delicious. Unlike the approach in this study, however, we go one step further and always recommend extra virgin olive oil from the first pressing of the olives to maximize phytonutrient quality. (The researchers in this study used virgin olive oil, not extra virgin). We also encourage purchase of organic olive oil and organic nuts whenever possible to maximize quality and minimize potential contaminants.