May 2016 Issue

Key Ingredients of the Mediterranean Diet — The Nutritious Sum of Delicious Parts
By Carrie Dennett, MPH, RDN, CD
Today's Dietitian
Vol. 18 No. 5 P. 28

Despite the frequent back-and-forth about what to eat—or not to eat—to promote health and wellness, some dietary patterns have stood the test of time, providing longevity and sustainability. The traditional Mediterranean diet is a hallmark example. The area bordering the Mediterranean Sea is culturally diverse, encompassing 23 countries, including Greece, Italy, Spain, France, Lebanon, Turkey, and the North African countries. While there's variance in which foods are traditional to a specific country, there's considerable overlap, giving rise to delicious and distinctive cuisines that share nutritional attributes.

In its classic, most studied form, the Mediterranean diet is how people in the olive-growing areas of Crete, Greece, and southern Italy ate in the late 1950s and early 1960s. According to leading Mediterranean diet researcher Antonia Trichopoulou, MD, PhD, president of the Hellenic Health Foundation and director of the World Health Organization Collaborating Center for Nutrition at the University of Athens (Greece) School of Medicine, this is the time period after the region overcame the economic difficulties following World War II and the people had enough to eat, but before socioeconomic changes introduced more meat, processed foods, and vegetable oils.

Overview
"The Mediterranean diet is a plant-based diet which does not say 'no' to meat," Trichopoulou says. Specifically, she says, the traditional Mediterranean diet is characterized by high consumption of vegetables, fruits, legumes, and unprocessed grains, low consumption of meat and meat products (maybe two to three times per month), and low consumption of dairy products.

All of this is bound by olive oil. "Olive oil is essential in defining the Mediterranean diet," Trichopoulou says. "You cannot consume vegetables and legumes in the quantity in which they are consumed in the Mediterranean diet unless they are cooked in olive oil." She says that a typical main dish at lunch or dinner consists of vegetables, legumes, and olive oil. What about fish? That depends on what part of the Mediterranean you're talking about. "The sea in Spain is very rich in fish, [but] the sea in Greece is not so rich in fish," she says.

Trichopoulou explains that the combination of the various components of the Mediterranean diet is more important than any one component in isolation. "There is significant evidence for an additive synergism between the components of the Mediterranean diet," she says. "Vegetables are stewed in olive oil with garlic, onion, and herbs, such as parsley, oregano, and basil. As a result, the end product provides, in addition to the macronutrients, many vitamins, minerals, and phytochemicals."

Health Benefits
The traditional Mediterranean diet is high in monounsaturated fatty acids, antioxidants, carotenoids, vitamin C, tocopherols (vitamin E), polyphenols (flavonoids in particular), anthocyanins, other vitamins and minerals, and dietary fiber.1-3 The diet's fat content is around 40% in Greece and 30% in Italy.1,4 Grains are whole or in the form of fermented sourdough breads or pasta cooked al dente, which lowers the glycemic index and the glycemic load. In addition to abundant phytochemicals, which have anti-inflammatory benefits, the whole and minimally processed plant foods also provide prebiotic fiber, which promotes intestinal health.5,6

Many observational studies have found that adherence to a Mediterranean diet is associated with reduced risk of several chronic diseases, including cancer, Parkinson's disease, Alzheimer's disease,7 type 2 diabetes,8 and cardiovascular disease (CVD),7,9-11 as well as all-cause mortality.7,12-14

"The benefits of the Mediterranean diet, especially when supplemented with extra-virgin olive oil, are supported not only by a fair number of observational cohorts but also by a randomized trial—namely, the PREDIMED trial," says Miguel Angel Martínez-González, MD, PhD, MPH, a professor and chair of the department of preventive medicine and public health at the University of Navarra in Pamplona, Spain.15,16 He's a coauthor of the landmark PREDIMED (PREvention con DIeta MEDiterranea) multicenter, randomized clinical trial, which assessed the long-term effects of a Mediterranean diet on the primary prevention of cardiovascular events.

PREDIMED enrolled 7,447 adults at high risk of CVD and followed them for eight years. One group followed a Mediterranean diet supplemented with olive oil, a second group followed a Mediterranean diet supplemented with nuts, and a third control group followed a lower-fat diet. Martínez-González says the results show that the benefits of a Mediterranean diet include a 30% relative reduction in heart attacks, stroke, and cardiovascular deaths, a 40% relative reduction in type 2 diabetes, a 68% relative reduction in peripheral artery disease, a 38% relative reduction in atrial fibrillation, and a 62% relative reduction in breast cancer.16

Key Ingredients
The Mediterranean diet is more than just a collection of foods and nutrients—it's an integral part and expression of the Mediterranean history and culture. It's also based on home cooking using local ingredients, which means that not all foods associated with the region are used in all areas.17,18 Even though each Mediterranean country has its unique foods and dishes, different foods provide similar nutrients, so the mechanistic effects of the nutrients and bioactive compounds are retained.2

Olive trees, vineyards, and wheat have been present in the Mediterranean region since the beginning, but because the region has been a geographical point of convergence for many different cultures, religions, and traditions, typical Mediterranean foods include those that are native to a particular area as well as those that were imported long ago.1 The following are some of the superstar foods in this delicious, nutritious, and health-promoting diet.

Olive Oil
Italy, Spain, and Greece are the top three producers of olive oil in the world, and olive oil is the common denominator in the varying dietary patterns that make up the overall Mediterranean diet. Extra-virgin olive oil is rich in tocopherols, carotenoids, and polyphenols, giving it antioxidant and anti-inflammatory properties.19,20 Olive oil is the principal source of dietary fat, and Trichopoulou is emphatic about the importance of olive oil in favoring high consumption of vegetables and legumes. Olive oil also is used for cooking and baking. Despite common beliefs to the contrary, high-quality extra-virgin olive oil has a high smoke point because of its lower free fatty acid content.21

Olives
Table olives, especially Kalamata olives, also are rich sources of antioxidant polyphenols.19 Olives are universally eaten whole, and are widely used for cooking and flavoring. Put pitted olives in a food processor with olive oil, garlic, and your favorite seasonings for a simple tapenade that makes a delicious dip, sandwich spread, or topping for fish and poultry. Toss pasta (cooked al dente) with chopped olives, tomatoes, garlic, olive oil, and fresh herbs of your choice. Add chopped olives to your favorite tuna or chicken salad recipe.

Wheat
Wheat is the foundation grain of the Mediterranean. One traditional grain is farro/emmer (Triticum dicoccum), an ancient wheat with renewed popularity in Italy and the United States. Bulgur is made from whole wheat berries that have been steamed, dried, and cracked, then used in pilafs, tabbouleh, and kibbe, a traditional Lebanese dish of minced meat with bulgur and spices. When choosing bulgur, use coarse for pilafs, medium for tabbouleh and other salads, and fine for making kibbe.

Breads often use unrefined wheat and barley flours. Durum, which has a creamy yellow color from the natural carotenoids, is the quintessential Mediterranean wheat, used for bread, couscous, and Italian pasta.22,23 Traditionally, wheat was ground with millstones, producing a fiber-rich whole-wheat flour with a lower glycemic index than the refined flours we see today.1 It also was leavened with sourdough starter, and this fermentation reduced the glycemic index of the wheat flour and improved digestibility.22

Wine
"Alcohol consumption was common in the traditional Mediterranean diet, but generally in moderation and in the form of wine and, as a rule, during meals—in the spirit of the ancient Greek word 'symposium,'" Trichopoulou says. Wine, red wine in particular, contains antioxidant polyphenols and the flavonoid resveratrol, and may help increase HDL cholesterol while decreasing LDL cholesterol levels.24

Wild Greens
Savory pies, tortes, or tortas made with greens are a staple dish in Greece, southern France, Italy, and other areas of the Mediterranean.25,26 Dandelion greens, fennel, cardoon, rocket (arugula), purslane, and chicory are just a few, and there are more than 150 types of wild greens on the Greek island of Ikaria alone.1,26,27 Although exact nutritional composition varies between species and cultivars, wild, dark leafy greens are rich in carotenoids, vitamins C and E, and minerals such as magnesium, iron, and calcium.17,27 Greens are rich in flavonoids, but not all greens are equally rich in the various flavonoid classes, so eating a variety of greens is optimal.25 Greens also provide plant-based omega-3 fatty acids.17,25,28 In North America, available edible wild greens include dandelion greens and purslane, as well as nutrient-rich cultivated greens such as kale, beet greens, mustard greens, and collard greens. Add them to frittatas, scrambled eggs, beans, and lentil soups. Sauté greens with garlic and finish with a squeeze of lemon, and enjoy raw salads of dark leafy greens dressed with an olive oil vinaigrette with or before a meal.

Capers
Capers generally are used as a flavorful, antioxidant-rich seasoning or garnish, and are an important ingredient in tapenade. "Quite often salad is sprinkled with oregano and olives, and capers and feta cheese are added," Trichopoulou says. Capers are fermented in sea salt, so while they are low in calories they are high in sodium, with one tablespoon containing 2 kcal and 250 mg of sodium. Rinsing capers under running water before using will remove some of the sodium (but not all, because they are brined) while still allowing them to retain their great flavor, reducing the amount of additional salt that will need to be added to the dish. The caper's pungency lends an appealingly sharp flavor to many sauces and condiments. They often can be used in place of olives.

Chickpeas (Garbanzos)
A half-cup of cooked chickpeas (82 g) is an excellent source of fiber (25% DV), folate (35% DV), and manganese (42% DV), and a good source of protein (15% DV), copper (15% DV), iron (13% DV), and magnesium (10% DV).29 (An excellent source contains 20% or more of the recommended DV based on a 2,000-kcal reference diet; a good source contains 10% to 19% DV.) One of the earliest known cultivated legumes, chickpeas are the key ingredient in hummus.30,31 A soup of black and regular chickpeas, fava beans, lentils, and whole wheat is an important traditional dish in Puglia, Italy.1 Chickpea flour is used to make a pancake or crêpe known as farinata or cecina in Italy or socca in the Cote d'Azur region of France. Chickpeas have a stronger inherent texture and aroma than many beans, which means they need fewer aromatics when cooking. For a Mediterranean-style snack, roast cooked chickpeas and salt them like peanuts.

Lemons
Acidic foods lower glycemic response by slowing stomach emptying.32,33 The acidity and high flavonoid content of lemon peels may have a beneficial impact on blood glucose, helping to control or prevent diabetes.34 Lemons and oranges originate from the Far East, and Arabs originally brought them to the Mediterranean.1 A common Mediterranean habit is to squeeze lemons on salads, fish, soups, and beans, and into drinking water, lowering the glycemic load of the entire meal.24 Lemon juice is a staple ingredient in hummus. Squeeze lemon juice over roasted broccoli or use it as all or part of the acid in a vinaigrette.

Garlic
Although garlic is an essential ingredient in all Mediterranean cuisines, how pronounced it is varies from province to province. Tzatziki, yogurt mixed with garlic, cucumbers, olive oil, red wine vinegar, and salt, is a common sauce in many Eastern Mediterranean cuisines. Mixing garlic with eggs and olive oil produces aioli. The sulfur compounds in garlic are responsible for both its pungent odor and most of its health benefits, which include anticancer, antioxidant, and anti-inflammatory effects.35 To maximize garlic's benefits, crush or chop the garlic and allow it to sit for 10 to 15 minutes before using it.

Herbs
Herbs are high in antioxidant and anti-inflammatory compounds, especially polyphenols. They contribute significantly to the overall dietary intake of flavonols and flavones in the traditional Greek cuisine.19 Each region in the Mediterranean has a different flavor palette, but herbs and spices are universally important in the Mediterranean cuisine. Do as they do in the Mediterranean and add fresh herbs to salads to increase the antioxidant capacity. Many of the classic herbs cultivated in North America grow wild along the roads in the Mediterranean.

Feta and Yogurt
Traditional feta and yogurt are fermented, making them rich in probiotics. They also provide additional protein to a diet that's largely plant-based. In addition to being found in the classic Greek salad, feta cheese often accompanies stews.2 Authentic Greek feta is made with goat's milk or sheep's milk. The Turks probably introduced yogurt, and it's more commonly used in the eastern Mediterranean (the old Ottoman Empire). Yogurt with honey is a common Greek breakfast.36 American feta tends to be drier and saltier than imported feta.

Bringing the Diet Home
The traditional Mediterranean diet is based on local foods37—but what if you're not local to the Mediterranean? "People could try to adjust their diets to the principles of the traditional Mediterranean diet," Trichopoulou says. "After all, this diet is not only health promoting, as the overwhelming evidence indicates, but also delicious, as many of those who have tried variations of it have readily acknowledged."

The Mediterranean diet provides a flavorful template for bringing healthful plant-based meals to the table. Whole grains and legumes are widely available in the United States, as are lemons, garlic, capers, feta, and plain yogurt. The herbs that provide so much flavor and a phytonutrient punch to Mediterranean meals also are beautiful additions to the garden landscape, making it easy and affordable to turn them into a kitchen staple. Look for the more deeply colored and more pungent or bitter greens, raw or cooked, instead of their paler cousins. If you keep a vegetable garden, sow some Italian dandelion (technically radicchio) and arugula seeds and you'll soon be able to pretend you're harvesting wild greens in Greece.

Preparing simple meals from fresh and minimally processed ingredients at home is a cornerstone of the traditional Mediterranean lifestyle, as is a balanced approach to eating that includes enjoying meat, sweet treats, and wine in moderation. As healthful as the Mediterranean diet is, one thing it is not is austere, and that's what makes it a sustainable approach to eating well. "It is highly palatable because of its relative high-fat content (mainly coming from olive oil and tree nuts), and therefore is highly accepted by the population at large," Martínez-González says. "There's a long and successful culinary tradition of the Mediterranean diet."

— Carrie Dennett, MPH, RDN, CD, is the nutrition columnist for The Seattle Times and speaks frequently on nutrition-related topics. She also provides nutrition counseling via the Menu for Change program in Seattle.

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