Nutrition

Mediterranean diet: history, health benefits, and environmental impact

The concept of the Mediterranean diet was first developed in the 1950s by the American physiologist Ancel Benjamin Keys. He described the relationship between diet and cardiovascular diseases (CVD), particularly through the epidemiological investigation known as the Seven Countries Study, the first to highlight the health benefits of the Mediterranean dietary pattern.[1][2][3]

Recognized as one of the healthiest models of nutrition, the Mediterranean diet is characterized by a high intake of minimally processed plant foods, such as vegetables, legumes, and whole-grain cereals, together with extra virgin olive oil as the main source of fats. As a result, this dietary pattern is naturally rich in antioxidant compounds and has well-documented anti-inflammatory properties.[4][5]

Following the Seven Countries Study, numerous investigations in both industrialized and non-industrialized populations confirmed the protective role of the Mediterranean diet, not only against CVD but also against chronic-degenerative diseases and depressive disorders. Evidence has also shown a positive correlation with improvements in cognitive performance and learning ability. Moreover, greater adherence to this dietary pattern is consistently associated with better overall health and reduced mortality.[6]

Importantly, no scientific evidence suggests that the Mediterranean diet is harmful to health. On the contrary, thanks to its reduced reliance on meat consumption, it contributes not only to individual well-being but also to public health, by helping lower greenhouse gas emissions.[7][8]

Ultimately, the Mediterranean diet represents a cultural and nutritional heritage that must be safeguarded and promoted, standing in contrast to the current global trend toward dietary uniformity.[9][10]

Contents

Ancel Keys and the Seven Countries Study

In the early 1950s, Keys identified a correlation between diet and cardiovascular disease risk by comparing the incidence of CVD among American business executives with that of European populations just emerging from World War II. In the former group, composed of well-nourished subjects, the incidence was high, whereas in the latter, affected by food insecurity, it was low. These observations led Keys to hypothesize a correlation between dietary fat intake and deaths from cardiovascular diseases.[11]

Subsequent observations revealed an extremely low incidence of coronary heart disease and certain cancers in the population of Crete, in much of the rest of Greece, and in southern Italy compared with the United States.[3] This led Keys to hypothesize that the diet of these populations, characterized by a low intake of animal fats, was protective, and to launch the long-term observational project known as the Seven Countries Study, the most influential longitudinal study on the Mediterranean diet.
This study demonstrated:

  • an inverse correlation between diet quality and both overall and cardiovascular mortality;
  • that saturated fats were the major dietary risk factor;
  • that adherence to a Mediterranean-type diet reduced the risk of developing cardiovascular diseases.[1][12]

Characteristics of the Mediterranean diet

The Mediterranean diet is characterized by the consumption of large amounts of vegetables, legumes, fruits, cereals (preferably whole grain), and extra virgin olive oil, which provides an abundant supply of fiber, antioxidants, phytosterols, polyphenols and unsaturated fatty acids.[5]

As for animal products, the consumption of meat, especially red meat and processed meat, as well as high-fat dairy should be limited, while fish and seafood should be included regularly. Alcohol consumption should be moderate, primarily in the form of red wine consumed with meals. In the Greek cohort of the EPIC study, extra virgin olive oil, vegetables, legumes, moderate alcohol intake, and low consumption of meat and meat products were identified as the main dietary components associated with reduced mortality.[13][14]

A cornerstone of the Mediterranean diet is extra virgin olive oil. It is an excellent source of monounsaturated fatty acids and contains over 2,000 different compounds, many of which have antioxidant activity.
Bottle of extra virgin olive oil, the cornerstone of the Mediterranean diet.As the main source of dietary fat, and when combined with low consumption of high-fat animal products, it ensures a high ratio of monounsaturated to saturated fatty acids, which improves lipid profiles and glycemic control in people with diabetes.[15][16]

However, it is misleading to focus on a single element of this dietary pattern. There is no “magic bullet”, as shown by studies examining isolated components. People do not consume nutrients individually but as part of a complex whole, and more importantly, these nutrients interact with each other in synergistic or antagonistic ways. Thus, the health benefits of the Mediterranean diet arise from the combined effect of all its components.[17]

The Mediterranean diet and chronic diseases

Since the Seven Countries Study, numerous investigations have demonstrated the effectiveness of this dietary pattern in both primary and secondary prevention of major chronic diseases, from cardiovascular conditions to depressive disorders, as well as in reducing overall mortality.
Here are some examples.

  • A meta-analysis evaluated the association between adherence to the Mediterranean diet, mortality, and disease incidence, showing that “greater adherence to a Mediterranean diet is significantly associated with a reduced risk of overall mortality, cardiovascular mortality, cancer incidence and mortality, and incidence of Parkinson’s disease”.[4]
  • A randomized multicenter study demonstrated its efficacy in the primary prevention of cardiovascular events in subjects at high cardiovascular risk.[18][19]
  • Adherence to the Mediterranean diet has been associated with a lower risk of Alzheimer’s disease, as well as a more favorable course and outcome. Higher adherence is linked to lower mortality, with evidence suggesting a dose–response effect.[20][21][22]
  • Mounting evidence suggests a protective effect against weight gain.[23][24]
  • An inverse association has been reported between adherence to this dietary pattern and the incidence of type 2 diabetes, both among initially healthy individuals and among patients who survived myocardial infarction.[25][26]
  • It is also associated with a lower prevalence of metabolic syndrome.[27][28]
  • Epidemiological and interventional studies have revealed a protective effect against low-grade chronic inflammation and its metabolic complications.[29][30]
  • There is also evidence that adherence to the Mediterranean diet may play a protective role in the prevention of depressive disorders.[31][32]

Its role in reducing greenhouse gas emissions

The Mediterranean diet can also improve public health by contributing to the reduction of greenhouse gas emissions, namely carbon dioxide (CO2), methane, nitrous oxide, and similar compounds, originating from the livestock sector, which is responsible for four-fifths of agriculture-related emissions. These emissions exceed those generated by transportation and are second only to those produced by the energy sector.[33][34][35]

Considering that the global population is growing, and that this growth is accompanied by an increase in per capita meat consumption, with estimates predicting an 85% increase in meat production by 2030 compared with 2000, the role of the Mediterranean diet in mitigating greenhouse gas emissions becomes even more evident.[36][37]

Greenhouse gas emission and cattle farming

A detailed analysis of greenhouse gas emissions from cattle farming, the main contributor within the livestock sector, shows the following distribution:

  • about 40% comes from the loss of annual plants, grasses, and trees that originally covered the land used to grow feed crops;
  • 32% from methane emissions generated by animal waste and by the animals themselves as a result of digestion;
  • 14% from the use of fertilizers to grow feed grain (approximately 16 pounds of grain are required to produce every kilogram of meat consumed);
  • 14% from agricultural production in general.

The table below compares CO2-equivalent emissions from the production of different foods (per 225 g portion) with the distance traveled by a gasoline-powered car consuming 1 liter of fuel every 12 km.

Comparison of CO2-equivalent emissions (g) for 225 g portions of various foods, relative to the distance (km and miles) traveled by a gasoline car (12 km/L fuel consumption)
Foods CO2 equivalent (g) Equivalent Distance (km/miles)
Potatoes 59 0.300 (0.17)
Apples 68 0.320 (0.2)
Asparagus 91 0.440 (0.27)
Chicken 249 1.17 (0.73)
Pork 862 4.10 (2.52)
Beef 3360 15.80 (9.81)

This comparison highlights the environmental impact of different food choices. Producing 225 grams of beef releases almost 13 times more greenhouse gases than producing an equal amount of chicken, and 57 times more than producing potatoes.
To put this into perspective, producing the 41 kilograms of beef consumed annually by the average American releases the same amount of CO2 as a gasoline car traveling approximately 3,000 kilometers.[38][39][40][41]

The Mediterranean diet is a proven path to health and longevity. Beyond personal wellness, it stands as a sustainable model, showing that what’s good for us is also good for the planet.

References

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