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September 11, 2015

Mediterranean Diet

Eat like a Mediterranean — but how?

Here's what the research says — and doesn't say — about the Mediterranean diet.

When they study the diet, researchers generally use scales of "Mediterranean-ness." On the most widely used of these, someone with a "perfectly Mediterranean" eating pattern would consume a high ratio of monounsaturated to saturated fats; a moderate amount of alcohol; plenty of legumes, grains, fruits, nuts, vegetables and fish; but scant meat and dairy. For the most part, these studies are done on large populations of people just living the way they normally live, and the closer those folks come to having a perfectly Mediterranean diet, the better their health and longevity tends to be.

A more detailed formulation of the Mediterranean diet — a four-tiered eating pyramid — was introduced in 1995 by scientists at the Harvard School of Public Health, the World Health Organization and Oldways Preservation and Exchange Trust, a nonprofit dedicated to changing the way people eat. An updated version was produced in 2008 and is endorsed by such respected health organizations as the Mayo Clinic and the Cleveland Clinic.

The ground floor of the 2008 version — foods you should "base every meal on" — is stuffed with fruits, vegetables, grains (mostly whole), nuts, legumes, seeds, olives, olive oil, herbs and spices. Next tier up — to be eaten next most frequently and at least twice a week — are fish and seafood. Then on level three come poultry, eggs, cheese and yogurt (daily to weekly in moderate amounts).

Perched at the very top are meats and sweets. You don't have to avoid these like the plague — just almost.For beverages, the plan calls for water and wine (in moderation) but notes that for some people the cons of alcohol may trump the pros.

What about those icons of Italian cuisine, pasta and pizza? Well, pasta can fit the Mediterranean bill if it's whole grain. So can a pizza if it sports a whole-grain crust and a vegetarian topping, with maybe just a smidgen of cheese. (Sigh.)

How does the Mediterranean diet do its good work?

Plant foods

A big chunk — fully 40% — of the credit for the reduced mortality rate associated with the Mediterranean diet can be attributed to the consumption of plant foods, according to the 2009 study that looked at the roles of various parts of the diet. (That's not including olive oil.)Plants make antioxidants and other beneficial chemicals to protect themselves (and especially the fruits, nuts and berries of their reproductive systems) from UV rays and harmful chemicals called free radicals, which are byproducts of metabolism.

We also need these beneficial chemicals to protect ourselves from free radicals, but we can't make most of them ourselves. "Our strategy is to get them from the plants by eating them," Cole says. Some are so important we need them for normal development; we call those "vitamins." But there are many others not essential for normal maturation that nevertheless promote health, Cole says.Plants also give us fiber (indigestible carbohydrates), which is shown to reduce the risk of heart disease, Type 2 diabetes and diverticulitis, not to mention constipation.However, fiber may not help ward off colon cancer, its most vaunted benefit. That link was based on relatively small studies, and it hasn't panned out in more recent, larger-scale research.

Wine

Drinking alcohol, in moderation, appears to be a big player in the benefits associated with the Mediterranean diet, garnering nearly a quarter of the credit for reduced mortality in the 2009 study. Reams of research have associated moderate alcohol consumption with healthy reductions in the risk of such serious problems as heart disease, ischemic strokes (ones caused by insufficient blood flow to part of the brain), Type 2 diabetes and gallstones.

There is considerable evidence, and even more speculation, that a non-alcoholic component of red wine, resveratrol, may confer health benefits of its own. In animals though not yet in humans, the compound has been shown to increase life span and inhibit the growth of cancer cells. And in a study published just this month, a daily dose of a resveratrol supplement led to a number of positive health effects for a small group of obese men, including a reduction in their blood pressure.

Moderate alcohol consumption can also pose dangers, including an increased risk of breast cancer and, in pregnant women, of birth defects in their babies. And for some people, at least, drinking can easily progress from moderate to immoderate. (The U.S. Department of Agriculture defines moderate alcohol consumption as no more than two drinks per day for men and no more than one for women or for any adults older than 65.) For this reason, many who recommend the Mediterranean diet counsel that the alcohol component is optional.

Fat

In the early 1960s, the percentage of total calorie intake coming from fat varied widely across Mediterranean regions: from 28% in southern Italy to 40% in Crete and other parts of Greece — one-third higher than the 30% that's generally recommended today. However much fat a Mediterranean diet includes, a lot of it is monounsaturated. That's because the diet gets most of its fat from olive oil, and most of the fat in olive oil is monounsaturated.

And not much of the fat in the Mediterranean diet is saturated because saturated fat is found mostly in foods that come from meat, dairy and poultry, and the diet minimizes those. A high ratio of monounsaturated to saturated fat is considered an intrinsic element of the traditional Mediterranean diet — and evidence shows that it's good for people's health. Saturated fat has detrimental effects on cholesterol levels and is associated with increased risks of heart disease and Type 2 diabetes; the opposite is true for monounsaturated fat. Monounsaturated may also help control insulin and blood sugar levels and thus help control Type 2 diabetes.But fat — even if it's good, non-artery-clogging fat — is still high in calories. In the 1995 paper introducing the Mediterranean diet pyramid, Willett and coauthors cautioned that Mediterranean populations in the early 1960s were very active, and a 40% fat diet in a more sedentary population might have less desirable results.

Is the Mediterranean diet just about food?

No. The 2008 Mediterranean diet also recommends physical activity and mealtime sociability.