It sounds like a happy hour dream: Now, scientists say, you can have your wine and eat the nuts that go with it, and be healthier in the bargain. A rigorous new study published in the New England Journal of Medicine should finally put to rest any doubts about whether a Mediterranean diet -- rich in olive oil or nuts as well as fish, with a glass of wine per day also allowed -- promotes better cardiovascular health than the way most of us eat. It does.
That might not be surprising, but up to now, advice on the Mediterranean diet has been based on correlation: People in Mediterranean areas that tend to follow that way of eating experienced lower incidence of stroke and other cardiovascular problems. Could the difference have been genetic? Could people who ate that way also be doing other things that made the crucial difference? The new study, conducted in Spain, randomly assigned a large number of subjects to different eating styles, made sure they were following it and measured results -- not lab-test results but illness and death.
But what about the long-standing battle between those who believe that a very low-fat diet is the best way to fend off cardiac risk, and those who espouse a way of eating much higher in the so-called good fats? Should all of the people carefully counting their daily fat grams give up the effort and take a spoonful of medicine in the form of olive oil? (Or, as the study had it, four tablespoons a day -- close to 500 calories of fat before you’ve eaten a solid thing.) Here the situation is much more complicated.
The study meant to compare the two. The control group was supposed to eat a low-fat diet. The problem, as reported in the New York Times and the Wall Street Journal, was that those people barely reduced their fat intake, even after receiving additional coaching. That’s why the article words things this way:
“We designed a randomized trial to test the efficacy of two Mediterranean diets (one supplemented with extra-virgin olive oil and another with nuts), as compared with a control diet (advice on a low-fat diet), on primary cardiovascular prevention.”
The researchers could have made that clearer at the get-go: Receiving advice on a diet isn’t the same as eating that way most days. So the actual comparison was between a Mediterranean diet and the standard way of eating among Spaniards (who apparently, in many ways, are not following a Mediterranean diet no matter what their geographical location happens to be).
What this study may have shown us about the difference between Mediterranean and low fat is that the former is easier to follow. There were no big problems getting subjects to ingest olive oil, wine and seafood. Low fat? Not so much.
The believers in low-fat diets could legitimately argue that the control group received too little coaching and support for their way of eating. But there’s also a reality that has to be taken into account. No matter what future research shows about the value of a low-fat or very low-fat diet, when it comes to improving public health, we might need not just a healthier diet but one that large numbers of people will find sustainable over a lifetime.