Greek, Italian or Spanish? What kind of Mediterranean-style diet are we talking about when we consider eating a Mediterranean diet? Talking about this right now at American College of Nutrition conference in New York City is Paul Jacques, S.c.D., FACN.
Well, mostly it's Greek, he says, which recommends eight servings of whole grains, six servings of vegetables, three servings of fruits, two servings of dairy, one and a half servings of wine, exclusive use of olive oil, fish, and little meat.
Many of the studies are based on the Greek Mediterranean-style diet.
So, Jacques captured the most frequently consumed foods based on NHANEs in the U.S. and tried to find how a Mediterranean diet could be followed in using 1,250 commonly consumed U.S. foods.
He found that the caloric intake would be about 2,680 kcal, 92 g protein, 361 g carbohydrate, 78g total fat, 41g fiber, 1155mg calcium, 521 mg magnesium, 3.9g of potassium (a little short).
However, there are studies that are on anything but the Mediterranean diet. He cites an example of a cohort study on Mediterranean dietary pattern and mortality among young women in Sweden. They found that young women who adhered closely to a traditional Mediterranean diet had reduced risk of mortality.
He's skeptical because "I find it hard to believe that there are really this many young women eating a Mediterranean diet" next to Baltic Sea.
There are also French studies that compared a traditional Mediterranean diet and a standard American Heart Association diet that found no difference in clinical outcomes.
As a summary, he presents a table of intervention studies of Med diet and adiposity that were six months or longer (several countries: Spain, Germany, Italy, U.S.). You can see that some type of diet intervention significantly lowers BMI.
But "a diet is only good if people can adhere to it," he says. So, he highlights one particular diet where it showed that people adhered more often to a Med diet than a low-fat diet.
Then, he shows the data of the famous Shi et al. DIRECT study from NEJM where it shows that people find it easier to adhere to a Med diet versus a low-carb or low-fat diet.
As far as observational studies, you must ask "Are the studies really on the Mediterranean diet?"
The ones that are percentile-based diet scores: Many are not based on specific recommendations, but arbitrary, population-specific values for assigning adherence and are not appropriate for use in non-Mediterranean countries.
A Mediterranean-style Diet Pattern Score (MSDS) is criterion-based score using recommendation from a Med diet pyramid, continuously scaled without arbitrary cut-off points, accounts for over-consumption of foods, and adjust for proportion of energy from non-Med-style foods.
"For example, where do French fries fall in the Mediterranean pyramid?" he says. The scoring is based on weighted scores with points per serving and penalizations. He shows us some equations he uses about how to develop the MSDPS scores.
He keeps reminding us that "no one really in the U.S. consumes the Mediterranean diet." So, he says, we have to be careful in saying that "greater adherence to a Med diet is associated with this or that." We have to be concerned about what exactly those patterns are; they may have a few more components to the Med diet, but not consuming a total Med diet.
It would be better to explain that people consuming a "partial Mediterranean diet" or whose diets "had more components of a Mediterranean diets" have improved metabolic traits. If you left it to Jacques, all the studies would be more specific in pointing out those components.
One prospective study on Med Diet Score and metabolic syndrome in a Spanish population (Tortosa et al, Diabetes Care, 2007) saw improvement in metabolic traits.
He goes on with other studies that show that "basically, adherence to Mediterranean diet based on commonly consumed foods in American's diets would largely address short-fall nutrients."
Few studies, particularly those in non-Mediterranean countries are not really the right diets. In spite of limitations, larger intervention studies demonstrate health benefits. And, again, more research is needed. Etc, etc.