A Tale of the Mediterranean Diet

The topic of the Mediterranean diet has been prevalent in the media lately and it is being touted as one of the healthiest diets to follow. The problem is that there is no concise definition of this diet. Most people have the impression that people of the Mediterranean region eat lots of fresh vegetables, especially tomatoes, along with mounds of pasta sprinkled generously with cheese, are fond of drizzling olive oil on practically everything and eat lean meat and seafood at least once a day. But is that actually the diet that often stands out in dietary studies as “the best”?

 

EVOLUTION OF THE MEDITERRANEAN DIET

There are more than twenty countries bordering the Mediterranean Sea and their diets are not all the same, however the term Mediterranean diet usually refers to the eating habits of the 1940s and 1950s in southern European countries including Greece, southern Italy, southern France, Spain and Portugal. The diets of these countries have evolved over time according to their religious, cultural, agricultural and economic influences. Around 400 BC Plato described a healthy Mediterranean diet as consisting of cereals, legumes, fruit, milk, honey, fish and water and cautioned that meat, candy and wine be consumed moderately. Later, the Roman Mediterranean diet was based on bread, wine and oil with the addition of some sheep’s cheese, vegetables and only a small amount of meat with preference for fish and seafood. Islamic culture in the area emphasized legumes and introduced grains and new food varieties such as eggplant, spinach, citrus, pomegranate, almonds and spices. Even the discovery of the New World had an influence with unfamiliar foods such as the tomato, now so common in the Mediterranean diet, along with potatoes, capsicum, corn, chili and more varieties of legumes making their way into the southern European diet (4).

The so-called Mediterranean diet first came to the forefront of Western consciousness in 1948 when the Greek government invited researchers from the Rockefeller Foundation of the USA to help them improve the poor living conditions in Crete at the end of the Second World War. Researchers observed that “olives, cereal grains, pulses, fruit, wild greens and herbs, together with limited quantities of goat meat and milk, game and fish consist the basic Cretan foods….no meal was complete without bread…..Olives and olive oil contribute heavily to the energy intake…..”(1).

In 1960 an American by the name of Ancel Keys took up the reins of this study that became known as the Seven Countries Study. Its aim was to look into the correlation between nutrition and cardiovascular disease. The study involved about 13,000 men selected from sixteen different regions in seven countries (Finland, Holland, Japan, USA, Italy, Yugoslavia and Greece). Results showed that, among these countries, the Greek population on the island of Crete manifested the best health and much lower rates of death from coronary disease and death from all causes. Incredibly the rate of fatal heart disease on Crete was twenty times lower than that of the United States at the time. The Cretans also had the lowest cancer rates amongst the seven countries. The only people on the island who showed high levels of heart disease were those who were members of the richest class and ate meat every day. Follow-up two decades later illustrated that the lower rate of death on Crete from coronary disease still persisted compared to that of the USA, north European populations and even populations from Italy, Yugoslavia and Corfu (2,3).

 

THE TRADITIONAL MEDITERRANEAN DIET EATEN ON THE ISLAND OF CRETE IN THE LATE 1950s AND EARLY 1960s

The diet was high in unprocessed plant foods such as grains, vegetables, fruits, legumes, nuts, seeds and extra virgin olive oil. Onion and garlic were eaten daily. Wild leafy greens were plentiful in this area and were a major part of many meals.
The diet was moderate in fish, shellfish, cheese and wine.
The diet was low in meat and dairy, eggs, animal fats and extras such as candy.
Only 7 percent of the diet’s energy came from animal origins such as meat, fish, eggs, and dairy products. The book “Food, A Culinary History” estimates that the ancient Greeks ate no more than four pounds of meat a year and in fact early Greeks viewed regular meat intake as being barbarian-like and greedy. They included animal meats in their diet once a week or less (20). This conviction endured into the 1950s. The meat that they did eat was cooked at low temperature and with high moisture, factors that reduce the formation of harmful by-products such as AGEs (Advanced Glycation End-products), PAHs (Polycyclic Aromatic Hydrocarbons) and HCAs (Heterocyclic Amines).

The pillars of the Cretan diet were legumes.
Dairy products such as yogurt and cheese were eaten on average about twice a week and fluid milk was reserved only for children.
Daily beverages included water, tea and coffee. Wine was consumed with meals and only if it conformed to religious practices.
Herbs and spices including oregano, one of the richest sources of polyphenols among herbs, were mixed into everything.
Cooking in olive oil was common. Butter and margarine were not consumed. (4)

An additional influence on the nutrition of the island of Crete at the end of World War II was the economic situation. The war, including prolonged occupation by the Nazis with formidable opposition from Cretan resistance fighters, left the island ravaged. Food was scarce and poverty was common. The resulting diet was actually an optimal one, consisting of 90% plants including fresh fruits, vegetables, whole grains, legumes and a small amount of fish, avocados, olives and olive oil. The residents were poor and could not afford to buy food such as extra meat, cheese or butter. Their consumption of animal products was restricted to those they managed to produce on their own.

 

THE MODERN DIET OF THE MEDITERRANEAN AREA

As is happening all over our world, the diet of residents along the Mediterranean coast has altered considerably in the last few decades and their health is paying the price. Studies of residents of Crete in 1991 found that hypertension had increased by 30% compared to 1960 levels and cardiovascular disease rates had increased from 8.8% in 1960 to 19.1% in 1991 (5,6). In 2014, the international organization OECD (Organisation for Economic Co-operation and Development) reported that Greece now holds the dubious position of having the highest numbers of death from heart disease and stroke among the 34 countries of the European South (7).

 

WHAT CAN THE MEDITERRANEAN DIET ACCOMPLISH FOR US IN THE 21ST CENTURY?

A meta-analysis and review of epidemiological studies and randomized controlled trials encompassing 534,906 participants showed that those who eat a long-term Mediterranean-style diet enjoy a decreased risk of metabolic syndrome with reductions in systolic and diastolic blood pressure, blood glucose levels, triglycerides and waist circumference and increases in the “good” HDL lipoprotein level. (18)

The Greek arm of the EPIC (European Prospective Investigation into Cancer and Nutrition) trial showed that a higher adherence to a traditional Mediterranean diet was associated with significant reduction in total mortality. This study followed over 23,000 men and women to evaluate the respective contribution to longevity of the nine widely accepted components of the traditional Mediterranean diet including;
High intake of vegetables, fruits, legumes, nuts, cereals, fish and seafood
Low intake of meat and meat products
Low intake of dairy products
High ratio of monounsaturated to saturated fats
Moderate intake of alcohol

The conclusions of this study state that the largest health benefits of a Mediterranean-style diet stem from the high proportion of plant foods (37% of the benefit) which can be further broken down into the benefit from vegetables of 16%, that from fruits and nuts of 11% and that from legumes at 10%. The REDUCTION of meat intake contributes 17% to the reduction of mortality. Moderate alcohol consumption too supplies some benefits. Olive oil and other monounsaturated fats were responsible for 11% of the lower mortality rate. As an aside, the health benefit of olive oil is related to its replacement of other oils higher in saturated fats. Minimal contributions were found for cereals and dairy products. Fish and seafood had no effect. (This is probably due to the actual low intake of fish and seafood in Greece). (9,16,17)

A meta-analysis of eleven prospective studies and randomized control trials (RCTs) showing the relationship between Mediterranean diet adherence and cardiovascular disease incidence and mortality was performed in 2014. Those who most closely followed a Mediterranean-type diet had a 24% decrease in mortality from cardiovascular disease, a 28% decrease in risk of coronary heart disease, a 33% decrease in myocardial infarction and a 24% decrease in stroke incidence. The protective effects of the diet appeared to be legumes, vegetables, fruits and olive oil (10).

A 2004 study showed that the proportion of legumes in a Mediterranean-style diet is the highest predictor of longevity. There is a 7 to 8% reduction in mortality risk for every 20 gm increase in daily legume intake (8).

The Lyon Diet Heart Study brought to light a 50% reduction in the risk of a second heart attack or other cardiovascular complication, fewer cancers and a significant decrease in all-cause mortality when eating in a traditional Mediterranean style. The authors highlight evidence that the adoption of a Mediterranean-style diet results in a much more significant reduction of new cancers as well as lower overall mortality than does the use of pharmaceuticals. They suggest that full adoption of a Mediterranean-style diet should be considered one of the most effective approaches for the prevention of fatal and non-fatal cardiovascular disease complications. (11,12,13).

 

THE PREDIMED TRIAL (14,15)

A recent trial from Spain, known as the PREDIMED trial, performed a comparison of the effect of different versions of the Mediterranean diet on almost 7,500 subjects who were at high risk for cardiovascular disease. Three diets were used – a control diet with participants only given advice to reduce dietary fat, a Mediterranean-style diet supplemented with extra-virgin olive oil and a Mediterranean-style diet supplemented with mixed nuts. Conclusions from the PREDIMED trial were that a Mediterranean-style diet supplemented with either extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events, however only the reduction in stroke incidence was statistically significant.

Let’s take a closer look at this trial. It appears that two interesting things happened during its five year course;

1 The control group, which was told to decrease fat intake, went from eating 39% of calories from fat to 37%. This is a high level even for the regular Western diet, which contains about 33% of calories from fat. A low-fat diet by the definition of the American Heart Association is less than 30% of calories from fat; a diet that can reverse coronary heart disease is less than 10% calories from fat.

2 The two groups eating the Mediterranean-style were told to eat more fruits and vegetables and less meat and dairy but they managed only minor adjustments over the course of the trial. In the end the three diets were pretty similar. The major difference between them was that the group receiving a free jug of extra-virgin olive oil weekly did increase their olive oil consumption from about three tablespoons daily to four. And the group receiving half a pound of nuts weekly increased their nut consumption from about half an ounce to one ounce a day.

Results showed no significant difference between the groups in their meat and dairy intake and therefore no difference in their saturated fat and cholesterol intake; no change in blood cholesterol levels; no alteration in the number of heart attacks, the risk of dying from a heart attack or stroke or the risk of early death from all causes. The only improvement was seen in the number of strokes that occurred. Those eating the extra nuts cut their risk of stroke in half while those eating the extra olive oil dropped their risk of stroke by one-third.

Notice that participants in all three groups experienced heart attacks at about the same rate. In this case, a Mediterranean-style diet did not provide protection from heart attacks.

 

UPDATE JUNE 13, 2018:  The New England Journal of Medicine retracted this study today due to irregularities in the randomization process and errors in results that were improperly reported.  A retraction is a last resort for scientific journals used only when results of a study are no longer trustworthy.  The 2013 paper is now replaced with a corrected version indicating only a correlation between the Mediterranean diet and fewer strokes and heart attacks, not that the Mediterranean diet was the direct cause of those health benefits.  (23)

 

HOW TO EAT A HEALTHY MEDITERRANEAN DIET (8,19)

Eat primarily plants comprising copious amounts of whole vegetables including leafy greens, legumes, fresh fruits and whole grains.
Eat nuts and seeds daily but in more moderate amounts.
Eat fish up to twice a week. They can provide healthy omega-3 fatty acids but unfortunately are also a source of toxic pollutants and heavy metals such as mercury.
Use abundant amounts of herbs and spices for flavour.
Limit salt.
Avoid red meat and meat products as much as possible. If you feel you must indulge then eat small portions at a maximum of only once a week.
Eat minimal amounts of poultry, twice a week at most.
Avoid eggs.
Keep dairy consumption low, including milk and cheese.
Limit use of added oils and butter. Use extra-virgin olive oil or canola oil in moderation.
Avoid sweets and other foods full of refined sugars.
If you drink alcohol choose red wine and imbibe moderately.
Enjoy meals with family and friends.
Get plenty of exercise.

 

IS A MEDITERRANEAN-STYLE DIET THE BEST WAY TO EAT FOR MY HEALTH?

A Mediterranean-style diet is substantially healthier than the standard Western diet. However, it is a step or two away from the diet that has been proven not only to stop the progression of heart disease but to reverse it (22). As researcher Dr. Caldwell B. Esselsyn Jr. states, “The present cardiovascular medicine approach tested beyond 40 years can neither cure the disease nor end the epidemic and is financially unsustainable. The safety, diminished expense, and prompt, powerful, and persistent results in treating the cause of vascular disease by whole-food plant-based nutrition offers a paradigm shift from existing practice.” (22). A diet derived from plants alone provides the most health-promoting foods available while at the same time avoiding those foods that can threaten health. It is plentiful in phytonutrients and antioxidants, fiber, vitamins, minerals and contains just the right proportions of healthy macronutrients (carbohydrates, proteins and fats). At the same time it limits exposure to animal-derived products which are a source of harmful saturated fats, pollutants and heavy metals while supplying no fiber or antioxidant ingredients and little in the way of vitamins and minerals.

Dr. Dean Ornish (see blog entitled “All About Heart Attacks Part Two”) gently reminded the authors of the PREDIMED study that, though a Mediterranean-style diet is better than what most people are eating, even better is a diet based on whole plants that is low in fat and refined carbohydrates. The authors replied that they were quite aware that Dr. Ornish’s diet could reverse heart disease but they believed that people would not be able to stick to such a diet, a frequent refrain from those unfamiliar with actual experience of a plant-based diet (21).

A plant-based diet is anything but boring, difficult or tasteless. There are many examples of people who not only adhere to such a diet but embrace it as one of the best decisions of their lives. Citizens of our modern world should be provided with all the pertinent nutritional facts and be allowed to decide for themselves how far they are willing to go for improvement of their health and enjoyment of life both immediately and into their future.

 

SOURCES:

1 Allbaugh, L.G. Crete: a case study of an underdeveloped area. Princeton NJ: Princeton
University Press, 1953

2 Keys, A., Menotti, A., Karvonen, M.J., Aravanis, C., Blackburn, H. et al. The diet and 15-year death rate in the seven countries study. Am J Epidemiol. 1986 Dec; 124(6):903-915.

3 Menotti, A., Kromhout, D., Blackburn, H., Fidanza, F., Buzina, R., Nissinen, A. Food intake patterns and 25-year mortality from coronary heart disease: cross-cultural correlations in the Seven Countries Study. The Seven Countries Study Research Group. Eur J Epidemiol. 1999 Jul; 15(6):507-515.

4 Radd-Vegenas, S., Kouis-Blazos, A., Singh, M.F. Evolution of Mediterranean diets and cuisine: concepts and definitions. Asia Pac J Clin Nutr 2017; 26(5): 749-763.

5 Voukiklaris, G.E., Kafatos, A., Dontas, A.S. Changing prevalence of coronary heart disease risk factors and cardiovascular diseases in men of a rural area of Crete from 1960 to 1991. Angiology. 1996 Jan; 47(1): 43-49.

6 Lanti, M., Menotti, A., Nedeljkovic, S., Nissinen, A., Kafatos, A., Kromhout, D. Long-term trends in major cardiovascular risk factors in cohorts of aging men in the European cohorts of the Seven Countries Study. Aging Clin Exp Res. 2005 Aug; 17(4): 306-315.

7 http://www.oecd.org/greece/Health-Policy-in-Greece-January-2016.pdf

8 Darmadi-Blackberry, I., Wahlqvist, M.L., Kouris-Blazos, A., Steen, B., Lukito, W., Horie, Y. et al. Legumes: the most important dietary predictor of survival in older people of different ethnicities.
Asia Pac J Clin Nutr. 2004; 13:217-220.

9 Trichopoulou, A., Bamia, C., Trichopoulos, D. Anatomy of health effects of Mediterranean diet: Greek EPIC prospective cohort study. BMJ. 2009; 338: b2337.

10 Grosso, G., Marventano, S., Yang, J., Micek, A., Pajak, A., Scalfi, L. et al. A comprehensive meta-analysis on evidence of Mediterranean diet and cardiovascular disease: are individual components equal? Crit Rev Food Sci Nutr. 2017; 57:3218-32.

11 de Lorgeril, M., Salen, P., Martin, J.-L,, Monjaud. I,, Delaye. J, Mamelle, N. Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: final report of the Lyon diet heart study. Circulation. 1999; 99:779-785.

12 de Lorgeril, M., Renaud, S., Salen, P., Monjaud, I., Mamelle, N., Martin, J.L. et al. Mediterranean alpha-linolenic acid-rich diet in secondary prevention of coronary heart disease. Lancet. 1994; 343:1454-1459.

13 de Lorgeril, M. Mediterranean diet and cardiovascular disease: historical perspective and latest evidence. Curr Atheroscler Rep. 2013; 15:370.

14 Estruch, R., Ros, E., Salas-Salvado, J., Covas, M.I., Corella, D., Aros, F. et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013; 368:1279-1290.

15 Martínez-González, M.A., Salas-Salvadó, J., Estruch, R., Corella, D., Fitó, M., Ros, E. Benefits of the Mediterranean diet: insights from the PREDIMED study. Prog Cardiovasc Dis. 2015; 58:50-60.

16 Trichopoulou, A., Costacou, T., Bamia, C., Trichopoulos, D. Adherence to a Mediterranean Diet and Survival in a Greek Population. N Engl J Med 2003; 348: 2599-2608J

17 Hu, Frank B., The Mediterranean Diet and Mortality — Olive Oil and Beyond. N Engl J Med 2003; 348: 2595-2596.

18 Kastorini, C.M., Milionis, H.J., Esposito, K., Giugliano, D., Goudevenos, J.A., Panagiotakos, D.B.
The effect of Mediterranean diet on metabolic syndrome and its components: a meta-analysis of 50 studies and 534,906 individuals. J Am Coll Cardiol. 2011 Mar 15; 57(11):1299-1313.

19 https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/mediterranean-diet/art-20047801

20 Jean-Louis Flandrin and Massimo Montanari (Editors). Food: A Culinary History. May 2013. Columbia University Press
21 Correspondence. Mediterranean Diet for Primary Prevention of Cardiovascular Disease . N Engl J Med 2013; 369:672-677. August 15, 2013.

22 Esselstyn, C.B. Jr, Gendy, G., Doyle, ., Golubic, M., Roizen, M.F. A Way to Reverse CAD? J Fam Pract. 2014 Jul;63(7):356-364b.

23 Estruch, R., Ros, E., Salas-Salvadó, J., Covas, M.-I., Corella, D., Arós, F. Retraction and Republication: Primary Prevention of Cardiovascular Disease with a Mediterranean Diet. N Engl J Med 2013; 368:1279-1290.