May 2020 Issue
Skeptics of the Med Diet
By Carrie Dennett, MPH, RDN, CD
Today’s Dietitian
Vol. 22, No. 5, P. 18
Are the criticisms of this traditional dietary pattern valid?
The Mediterranean diet (Med diet) was named “Best Overall Diet” for 2019 by U.S. News and World Report, and recent research has found that adherence to a Mediterranean dietary pattern is associated with reduced risk of anxiety and depression,1,2 improved quality of life in adults with type 1 diabetes,3 and lower risk of late-onset Crohn’s disease.4
Despite an extensive body of research, this nutrient-rich diet has its detractors. What do science and tradition say about claims made by critics?
Claim #1: The Med diet is unaffordable.
This claim stems from the fact that quality olive oils can be expensive, and many Mediterranean staples, such as fresh tomatoes and leafy greens, may be more costly when they’re out of season here in the United States. And then there are the pricey, high-end Mediterranean-inspired restaurants. But are those fair representations of the traditional Med diet?
“The Mediterranean diet is actually quite humble in its roots, based on simple ‘peasant foods’ like grains, beans, and seasonable vegetables,” says Kelly Toups, MLA, RD, LDN, director of nutrition at Oldways. “Animal products were more expensive, so thrifty Mediterranean cooks used smaller portions to garnish and flavor dishes, while the low-cost pantry staples made up the bulk of the meal. Compared with the expensive supplements and snack foods being promoted today, a traditional Mediterranean diet flies in the face of long-held assumptions that wholesome diets cost an arm and a leg.”
The Med diet has come to be viewed, at times, as “elitist,” especially when transplanted from its peasant roots to an urban North American setting. However, while some Mediterranean staples cost more than they used to, research confirms that healthful diets—including the Med diet—need not be expensive. A 2009 review in Public Health Nutrition concluded that the Med diet—whether the traditional or the North American modified version—offers a social and culinary framework for incorporating nutritious, low-cost foods into the diet.5
A 2008 study in Quebec City found that total daily dietary cost was the same—and total daily energy density was lower—at the end of a 12-week Med diet intervention study compared with the total daily dietary cost at the start of the study. The authors say the key to avoiding increased overall dietary costs is encouraging consumers to prioritize lower-cost foods such as pulses while selectively purchasing limited amounts of higher-cost foods. They also observed an association between planning food purchases based on weekly discounts in grocery store flyers and reduction of food costs following the intervention.6
A 2013 study of the effects of a six-week cooking program at The Rhode Island Community Food Bank that focused on plant-based cooking with olive oil found that, at the end of the six-month study, the 63 participants purchased less meat, poultry, or seafood; more fruits and vegetables; and fewer desserts, snacks, and carbonated beverages. They also spent less on food overall—almost $68/week at baseline vs $37/week at the six-month follow-up.7 A 2015 study by two of the same authors found that an economical version of the MyPlate diet cost $746 more per year—and provided fewer servings of vegetables, fruits, and whole grains—than a plant-based diet with olive oil.8
While that’s encouraging, Toups does emphasize that today’s global food economics are at least somewhat out of touch with public health, noting that a Bacon McDouble is only $2 at most McDonald’s restaurants, whereas broccoli florets run $2.36 per lb on average, according to the USDA. “There’s no question that most Americans would benefit nutritionally from choosing more green vegetables and fewer servings of red and processed meat,” she says. “Which begs the question—is it fair to criticize healthful, traditional diets, or should we turn our attention to the food system itself, which tends to externalize the true costs of highly processed, nutrient-poor foods?”
Claim #2: Liquid oils, even olive oil, are unhealthful.
The claim—promoted by some, but certainly not all, plant-based diet advocates—is that we shouldn’t consume oils, even olive oil, because they’re highly refined, contain no nutrients other than fat, and have a negative impact on blood vessels, increasing the risk of heart disease.
“Oil is pure fat, but that doesn’t mean it has no nutritional value,” says Baltimore-based Monica Reinagel, MS, LD/N, CNS, owner of nutritionovereasy.com and host of the Nutrition Diva podcast. “Monounsaturated fatty acids in olive oil have many health benefits; the polyphenols have many health benefits.”
While some oils are highly refined, including the so-called “light” olive oil, extra-virgin olive oil is, effectively, pressed olives. Furthermore, although olive oil is 98% to 99% fatty acids, especially monounsaturated fatty acids, the remaining 1% to 2% is made up of a number of bioactive compounds, including polyphenols and tocopherols.9,10
“I feel like ‘refined’ is kind of a loaded and imprecise word that has this association with ‘refined sugar,’” Reinagel says. “No one’s going to sit down and drink a glass of olive oil. We use it to roast our vegetables, to dress our salads,” she says, adding that olive oil makes vegetables more appealing and helps us absorb fat-soluble nutrients in the vegetables, such as vitamins A and K, beta-carotene, and lycopene. “It’s bringing nutrients into the diet, not displacing nutrients out of it.” She says this is very different from foods that are pure sugar, which often are consumed in isolation and displace more nutritious foods.
The claim that oils harm blood vessels is based on decades-old studies, primarily animal and in vitro studies. One often-cited study from 2000 involved just 10 healthy subjects. It found that olive oil, unlike canola oil and omega-3 fatty acid–rich salmon, impaired the function of the endothelium (blood vessel lining) following a meal of oil and whole grain bread. The meals were 900 kcal with 50% of calories from fat. Specifically, flow-mediated vasodilation in the brachial artery was comparatively less after the olive oil and bread meal. However, this difference was mediated when that meal was accompanied by a salad, or by supplemental antioxidants, which places it in a more “real meal” context. In addition, the authors emphasized that it’s unclear whether the observed endothelial changes predict future CVD.11
However, a 2019 review found that olive oil, alone or in the context of a Med diet, has been observed to have beneficial effects on several more recently identified cardiovascular risk factors, including inflammation, oxidative stress, coagulation, and platelet aggregation, as well as endothelial function.12,13
One thing the oil critics get partially right is that, unfortunately, the phrase “Mediterranean diet” has become synonymous primarily with olive oil. This sort of nutrition reductionism misses the fact that the Med diet is composed of multiple components—fruits, vegetables, whole grains, pulses (beans and lentils), seafood, nuts, herbs, and fermented dairy—that each contribute health-promoting nutrients to the diet, but likely act synergistically to support health. Cooking or dressing vegetables and pulses with olive oil encourages their consumption, but the Med diet isn’t about the olive oil—or the red wine—it’s about the whole dietary package.
Claim #3: The Med diet is about pasta, and we shouldn’t eat pasta.
While pasta is one staple food in some countries that follow classic Mediterranean-style diets, none of the cuisines that make up this region are one-note wonders.
When pasta is cooked al dente—still firm to the bite—it has a relatively low glycemic index. Pasta also contains resistant starch (starch in foods that’s resistant to digestion in the small intestine), which serves as a food source for beneficial microbes in the large intestine.14
A 2017 study using National Health and Nutrition Examination Survey data from 2009–2012 found that consumers of pasta noodles and pasta mixed dishes—excluding macaroni and cheese—had more healthful diets as measured by Healthy Eating Index scores and consumed more fiber.15 Another 2017 study, published in the Journal of the Academy of Nutrition and Dietetics, found that pasta eaters had higher daily consumption of vegetables than nonpasta-eaters and had higher consumptionof red-orange vegetables, includingtomatoes, when they ate pasta.16
Claim #4: The Med diet doesn’t make sense outside of the Mediterranean region.
While the exact foods may vary, Toups says the roots of the Med diet also are reflected in the foundations of many other healthful diets around the world. “Food cultures are dynamic and constantly changing. Many people are surprised to learn that iconic ‘Mediterranean’ ingredients like tomatoes and polenta actually trace their roots to the Americas in pre-Columbian times,” Toups says. “While a Mediterranean diet isn’t the only path towards good health and well-being, people shouldn’t let geography be a deterrent from incorporating the foods, flavors, and overall principles of a traditional Mediterranean diet.”
The Med diet has been investigated outside of the Mediterranean in many large studies. For example, a 2019 study of 16,948 middle-aged adults in China, published in The American Journal of Clinical Nutrition, found that those closely following a Med diet were 33% less likely to develop cognitive impairment after 20 years of follow-up than those not following a Med diet.17 Similarly, in a 2017 study of 24,882 Chilean adults, those most closely following a Med diet were less likely to have metabolic syndrome and more likely to have a BMI in the normal range.18 In the United States, data published in 2007 from the National Institutes of Health-AARP Diet and Health Study, which included 214,284 men and 166,012 women, showed that conformity to a traditional Mediterranean diet score and the alternative Mediterranean diet score was associated with a significant reduction in all-cause mortality, including mortality due to cancer and CVD.19
Claim #5: Even people living in the Mediterranean don’t follow the Med diet.
Indeed, fast food and other convenience foods typically associated with the “Westernization” of traditional diets—along with food advertising to children—has hit Greece and other Mediterranean countries.20 But one also could make the argument that the modern Standard American Diet bears little resemblance to the Healthy US-Style Eating Pattern recommended in the Dietary Guidelines for Americans.21
Developing nations undergoing “nutrition transitions”—periods in which problems of undernutrition coexist with food-related chronic diseases—tend to replace their traditional plant-based diets with more energy-dense foods containing added sugars and fats because they taste good, are convenient, and may be more affordable. The Mediterranean countries haven’t been immune to these dietary trends. Longitudinal analyses show that the diet of the Mediterranean nations has become much higher in both sugar and fat and more homogeneous than it was in the 1960s when the traditional Med diet was rich in grains, plant foods, and fish, with limited amounts of red meat.5
Ironically, it appears the Mediterranean countries that had the highest adherence to a Med diet pattern in the 1960s have experienced the greatest decreases in adherence as measured by the Mediterranean Adequacy Index. At the same time, countries in Northern Europe and around the world are embracing a Mediterranean-like dietary pattern, possibly due to increased availability of Mediterranean food products such as fruits and vegetables.22
Currently, adherence to the Med diet in Mediterranean countries is associated with socioeconomic status, whereas, before the recession that began in 2007–2008, there was no association.22 Because energy-dense convenience foods are a low-cost source of calories, they’re more likely to be consumed by lower-income groups, as they supply more calories but fewer nutrients per gram.5
“As traditional diets get replaced with convenience foods and sugary snacks, it’s more imperative than ever that food and nutrition professionals around the globe help keep these traditions alive and preserve some of the healthful habits that helped people ward off chronic diseases and diet-related illnesses in generations past,” Toups says.
In 2010, the UNESCO (United Nations Educational, Scientific and Cultural Organization) and Food and Agriculture Organization (FAO) recognized the Med diet as a representation of intangible cultural heritage. In a 2015 whitepaper, the FAO pointed to the abandonment of traditional habits and the emergence of new lifestyles associated with socioeconomic changes as threats to the preservation and transmission of the Med diet to future generations. They say it’s urgent to preserve the cultural heritage of the Med diet because of its benefits to both health and the environment.23
Claim #6: It’s untrue that they don’t eat much meat in the Mediterranean.
The Mediterranean dietary pattern that has been studied in epidemiologic and clinical research is based on foods that traditionally have been consumed by coastal communities situated along the Mediterranean Sea.
While there are Mediterranean food cultures and recipes that include more meat, these come from areas away from the coast, and aren’t reflected by the Mediterranean Diet Pyramid, which is largely based on the dietary traditions of the Greek island of Crete and southern Italy around the 1960s, when rates of chronic disease were among the lowest, and adult life expectancy among the highest, in the world.
In these coastal communities, seafood and legumes provided much of the available protein, while other animal proteins, such as meats and cheeses, were enjoyed in smaller portions, Toups says. Dried pulses, such as chickpeas, lentils, and cannellini beans offered a more affordable source of protein to Mediterranean people that also was shelf stable—an important feature before refrigeration became widespread.
Mediterranean culture before the mid-20th century drew heavily from religious faiths (Greek Orthodox and Roman Catholicism as well as Islam and Judaism), which dictated frequent periods of fasting from meats and poultry, Toups says. This fact contributes to the criticism that some of the data used in Ancel Keys, PhD’s, original Seven Countries Study, which first drew research attention to the potential health benefits of a Med diet, were collected in Greece during Lent, one of those religious fasting periods. However, dietary records showed no significant differences between foods eaten during Lent and at other times, largely because actual practice didn’t match church prescriptions, and, even during nonfasting times, meat and poultry intake was low.24
“Today, when researchers study the impact of the Mediterranean diet, they typically measure people’s adherence to the Mediterranean diet using one or more scoring tools,” Toups says. “While the scoring tools differ from one study to the next, it’s clear that a Mediterranean diet low in meat and higher in seafood and plant proteins is associated with far-ranging health benefits.”
• The Mediterranean Adequacy Index is calculated by dividing the sum of the percentage of total energy from typical Mediterranean food groups by the sum of the percentage of total energy from nontypical Mediterranean (eg, meats, eggs, cookies, industrially processed dishes) food groups.25,26
• The Mediterranean-Style Dietary Pattern Score allows for one serving of meat, four servings of poultry, four servings of legumes/nuts/olives, and six servings of seafood per week, in addition to other foods.27
• In the PREDIMED study, a large clinical trial of the Med diet, those in the Med diet group were encouraged to choose white meat instead of red meat, have at least three servings of seafood per week, and at least three servings of legumes per week.28
Bottom Line
The Med diet, as represented by the Mediterranean Diet Pyramid and various Med diet scoring tools, is an eating pattern based on tradition and supported by science.29 While it’s not the only healthful, nutrient-rich dietary pattern, the traditional Med diet offers numerous options for culinary variation, which may be appealing to clients. When planned well, it can be affordable, and it also appears to be environmentally sustainable.
— Carrie Dennett, MPH, RDN, CD, is the nutrition columnist for The Seattle Times, owner of Nutrition By Carrie, and author of Healthy for Your Life: A Holistic Guide to Optimal Wellness.
References
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