The Mediterranean diet is a diet inspired by the eating habits and traditional food typical of southern Spain, southern Italy, and Crete, and formulated in the early 1960s.^[1] It is distinct from Mediterranean cuisine, which covers the actual cuisines of the Mediterranean countries, and from the Atlantic diet of northwestern Spain and Portugal. While inspired by a specific time and place, the "Mediterranean diet" was later refined based on the results of multiple scientific studies.^[2]

This approach emphasizes a plant-based diet, focusing on unprocessed cereals, legumes, vegetables, and fruits.^[3][4] It also includes moderate consumption of fish, dairy products (mostly cheese and yogurt), and a low amount of red meat.^[3][5] Olive oil has been studied as a potential health factor for reducing all-cause mortality and the risk of chronic diseases.^[6]

The Mediterranean diet is associated with a reduction in all-cause mortality in observational studies.^[7][8] A 2017 review provided evidence that the Mediterranean diet lowers the risk of heart disease and early death.^[9] The Mediterranean diet may help with weight loss in obese people.^[10] The Mediterranean diet is one of three healthy diets recommended in the 2015–2020 Dietary Guidelines for Americans, along with the DASH diet and vegetarian diet.^[11]

As a nutritional recommendation, the Mediterranean diet is different from the cultural practices identified by UNESCO in 2010 under the heading "Mediterranean diet" on the Representative List of the Intangible Cultural Heritage of Humanity, which defined the diet as "a set of skills, knowledge, rituals, symbols and traditions concerning crops, harvesting, fishing, animal husbandry, conservation, processing, cooking, and particularly the sharing and consumption of food".^[12][13]

A 2017 review found evidence that practice of a Mediterranean diet could lead to reduced risk of cardiovascular diseases, overall cancer incidence, neurodegenerative diseases, diabetes, and early death.^[9] A 2018 review showed that practice of the Mediterranean diet may improve overall health status, such as reduced risk of non-infectious diseases, reduced total costs of living, and reduced costs for national healthcare.^[14] A 2016 review found similar weight loss as other diets.^[15] A 2019 Cochrane review found that there is still uncertainty regarding the effects of Mediterranean‐style diet advice on cardiovascular disease occurrence and risk factors in people both with and without existing cardiovascular disease.^[16]

The US 2015–2020 national guidelines devised a "Healthy Mediterranean-Style Eating Pattern", assessed against and mirroring the Mediterranean diet patterns and its positive health outcomes. It was designed from the "Healthy U.S.-Style Eating Pattern", but it contains more fruits and seafood, and less dairy.^[11] In the 2020s, research on the Mediterranean diet indicates that a Mediterranean diet may contribute to health.^[17]

There are variations of the "Mediterranean diets" in different countries and among the individual populations of the Mediterranean basin, due to ethnic, cultural, economic and religious diversities.^[46] The "Mediterranean diet" as defined by dietitians generally includes the following components,^[10] which are not typical of diets in the Mediterranean Basin:^[47][48]

• High intakes of olive oil (as the principal source of fat), and a plant-based diet: vegetables (including leafy green vegetables, onions, garlic, tomatoes, and peppers), fresh fruits (consumed as desserts or snacks),^[4] cereals (mostly whole grains), nuts, and legumes.
• Moderate intakes of fish and other seafood, poultry, eggs, dairy products (primarily cheese and yogurt), and red wine.
• Low intakes of red meat, processed meat, refined carbohydrates, and sweets.

These proportions are sometimes represented in the Mediterranean Diet Pyramid. In a diet with roughly this composition, the fat content accounts for 25% to 35% of the total intake of calories, while the amount of saturated fat is, at most, 8% of the calorie content.^[48]

Some cuisines of the Mediterranean region are not fully consistent with Mediterranean diet guidelines. For instance, olive oil is not the staple fat in the cuisines of all countries which border the Mediterranean: in northern and central Italy, lard and butter are commonly used in cooking, and olive oil is reserved for dressing salads and cooked vegetables;^[49] in both North Africa and the Middle East, sheep's tail fat and rendered butter (samna) are traditional staple fats.^[50]

Consuming a Mediterranean diet or plant-based diet may contribute to improving environmental and agricultural sustainability, possibly due to lower use of dairy products, ruminant meat, and ultra-processed foods.^[56] The environmental impact and amount of energy needed to feed livestock exceeds its nutritional value.^[57][58] In a 2014 lifecycle analysis of greenhouse gas emissions, researchers found that a Mediterranean-like diet may reduce food production emissions below those of an omnivorous diet for 2050, with a per capita reduction of 30%.^[59][60]

The concept of Mediterranean diet was first publicized in 1975 by the American biologist Ancel Keys and chemist Margaret Keys (a husband and wife team),^[61] but failed to gain widespread recognition until the 1990s.

Objective data showing that the Mediterranean diet is healthy originated from results of epidemiological studies in Calabria,^[62] Naples and Madrid, confirmed later by the Seven Countries Study first published in 1970,^[63] and a book-length report in 1980.^[64]

The most commonly understood version of the Mediterranean diet was presented by, among others, Walter Willett and colleagues of the Harvard University School of Public Health since the mid-1990s.^{[65][66][67][68]} The Mediterranean diet is based on a paradox: although the people living in Mediterranean countries tend to consume relatively high amounts of fat, they have far lower rates of cardiovascular disease than in countries like the United States where similar levels of fat consumption are found. A parallel phenomenon is known as the French paradox.^[69] By 2011, the Mediterranean diet was included by some authors as a fad diet promoted for losing weight.^[70]

Since about 2016, the American Heart Association and American Diabetes Association have recommended the Mediterranean diet as a healthy dietary pattern that may reduce the risk of cardiovascular diseases and type 2 diabetes, respectively.^[28][71][32] The United Kingdom's National Health Service also recommends a Mediterranean diet to reduce cardiovascular disease risk.^[72][73]

In 2018, the European Journal of Public Health questioned the value of the traditional Mediterranean diet due to homogenization of dietary choices and food products in the global economy.^[14] Despite this, clinical research activity remained high, with favorable outcomes reported for various disease conditions, such as metabolic syndrome.^[74]