5 takeaways from the newly published Mediterranean Diet study
Recently a study about the heart benefits of the Mediterranean Diet - (Funded by the Spanish government's Instituto de Salud Carlos III and others - was published at the February 25th issue of the New England Journal of Medicine. What do we learn from the study? Here are 5 takeaways from the newly published study regarding the Mediterranean diet, discussed by James Barnard, PhD, UCLA Distinguished Professor Emeritus, Department of Integrative Biology and Physiology.
1. The study affirmed the benefits of healthy eating even for people already taking medications for high cholesterol, blood pressure, or diabetes. The takeaway: Drugs are beneficial, but drugs combined with a healthy diet are even more beneficial.
2. The study was large – following 7,447 people who were randomly assigned to either Mediterranean-style diets or a low-fat diet – and seemingly well designed. But a major problem with the study was that the low-fat diet was not low in fat. The people in the "low-fat" group started out with a diet that was 39% fat. They decreased fat intake to 37%.
Therefore, the authors weren't really comparing a Mediterranean diet to a low-fat diet. It's much more accurate to say they were comparing a Mediterranean diet to a typical American-style diet. That’s because a lot of the foods the so-called "low-fat" group was eating were heart-damaging foods like red meat, commercially baked goods full of refined flour and fat, sugary sodas, and low-fat cheeses. (Though called "low-fat," these cheeses typically get 35 to 60% of their calories from fat.)
3. Some argued that the people in the "low-fat" group were unsuccessful in reducing their fat intake because a low-fat diet is too difficult to maintain, but it could also be argued that the scientists conducting this study never really gave the "low-fat" diet group much of a chance.
During the first half of the study, the people assigned to the Mediterranean diet received intensive education in eating well, including regular visits with registered dietitians. The people in the "low-fat" group got just one visit. That's it. It was the equivalent of a doctor's visit in which the doctor hands you a pamphlet with what to eat, and what not to eat, and essentially says, "Good luck."
Moreover, the "low-fat" diet that the scientists designed excluded an important food proven to protect against heart disease, a food that is a part of many low-fat plans, including the Pritikin Program – omega 3-rich fatty fish. The subjects in the study were discouraged from eating fatty fish like salmon.
And ironically, this "low-fat" diet devised by the scientists had no limits on some foods known to increase heart disease risk, like soft drinks.
4. The scientists summarized that the Mediterranean diet "reduced the incidence of major cardiovascular events" compared to a low-fat diet, and media articles on the day the study was published led with announcements like "30% of heart attacks, strokes, and deaths from heart disease were prevented."
But in the study itself, the scientists reported no significant reductions in heart attacks or cardiovascular-related deaths among the Mediterranean dieters. They wrote, "Only the comparison of stroke risk reached statistical significance."
So how did they jump from stroke reductions to all reductions in cardiovascular risk? Well, it's easy when you know how to play with numbers. They pooled all the data on heart attacks, strokes, and deaths, and the numbers on strokes were high enough so that the average of the three looked good.
5. What would have been a far better study is one in which a Mediterranean diet was compared with a truly healthy low-fat plan like Pritikin. Pritikin includes all the excellent elements of a Mediterranean diet (fruits, vegetables, whole grains, legumes, fish) as well as the ability to shed excess weight (something the subjects in the Mediterranean study did not achieve) because on Pritikin calorie-dense foods like oil and nuts are kept to a minimum.
So strong are the data affirming the heart-healthy benefits of the Pritikin Program that Medicare is now covering it for people with a history of cardiovascular disease.
By James Barnard, PhD, UCLA Distinguished Professor Emeritus, Department of Integrative Biology and Physiology
* New England Journal of Medicine, February 25, 2013; DOI: 10.1056/NEJMoa1200303
Also see Dr. Gayl Canfield's story discussing the pros and cons of the Mediterranean Diet. What each follower of this diet should know about the advantages and disadvantages of this plan.
What is your opinion about the benefits of the Mediterranean Diet? Is this a diet or should be a lifestyle? Share your opinion in the comments section please.
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