The Mediterranean Diet Study: Just Say ‘Nuts!’ to the Low-Fat Diet?

Henry R. Black, MD


March 14, 2013

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Hi. I'm Dr. Henry Black, Clinical Professor of Internal Medicine at the New York University Langone Medical Center in New York City and former President of the American Society of Hypertension.

A very interesting study about the Mediterranean diet was recently published.[1] The news media loved it and patients loved it. It is a very important study for many reasons. It was large, including about 7400 individuals from the Mediterranean area, primarily from Spain. The investigators compared 2 so-called Mediterranean diets (one supplemented with extra-virgin olive oil and one supplemented with nuts) with a low-fat diet, which we tend to consider appropriate for heart disease and stroke prevention.

The interesting thing about this study is that the participants were very high-risk people. More than 80% of patients were hypertensive, about 40% had diabetes, and they were on multiple medications. Usually we start with the diet as a platform and add medicines rather than start with the medicines and change the diet. The problem with all nutritional studies thus far, with 1 or 2 exceptions, is that they were very small. They used surrogate endpoints, they didn't have outcomes, and people got very confused. One day a certain diet was recommended and the next day another diet was recommended. What do we do?

The important thing about this Mediterranean diet was that there was a 30% reduction in the primary endpoint, which was a combination of stroke, myocardial infarction, and death. The only one that was individually significant was stroke. Considering that weight loss was not recommended, exercise was not necessarily recommended. Participants who were on the Mediterranean diet got extra sessions at the beginning, which was not seen for the control diet (the low-fat diet) initially, but it was added later.

The study was stopped early because the Mediterranean diet was successful. They also looked at whether adding walnuts was better than adding extra-virgin olive oil. Both resulted in pretty much the same reduction in the primary endpoint.

One of the things that we have heard is that there are no outcomes studies using a nutritional intervention. That is no longer the case. This became so important that when I went to my local Trader Joe's, I couldn't get walnuts. A lot of people have heard about it and I think this is a good way to eat.