What Is the Mediterranean Diet? Principles, Foods and the Evidence Behind It

The Mediterranean diet is not a single recipe book but an eating pattern modeled on the traditional cuisines of countries bordering the Mediterranean Sea, particularly Greece and southern Italy in the mid-20th century. According to Harvard's T.H. Chan School of Public Health Nutrition Source, it is best described as an eating pattern rather than a strictly regimented diet plan, built around plant foods and olive oil rather than any single 'superfood.'

How the pyramid is organized

In 1993, Oldways Preservation and Exchange Trust worked with the Harvard School of Public Health and the WHO's European office to create the Mediterranean Diet Pyramid, intended as an alternative to the original USDA food pyramid, according to Oldways. The pyramid's base is not a food group at all: it represents daily physical activity and shared, social meals, reflecting that the pattern is treated as a lifestyle rather than a list of ingredients.

Above that foundation, Oldways lists the foods people are meant to shop for and eat every day: whole grains, fruits, vegetables, beans and other legumes, nuts, herbs, spices and healthy fats such as olive oil. Fish and seafood are recommended at least twice a week. Dairy, especially fermented forms like yogurt and traditional cheese, is eaten frequently but in moderate portions, while eggs and poultry appear only occasionally. Red meat and sweets sit at the top of the pyramid and, per Oldways' description, are meant to be eaten only rarely.

Daily, weekly and monthly guidance

Harvard's Nutrition Source breaks the pattern into similar tiers. Whole grains, olive oil, fruits, vegetables, beans, legumes, nuts, herbs and spices are positioned as daily staples, with water as the primary beverage. Fish or seafood is suggested at least twice weekly, while poultry, eggs and dairy such as cheese and yogurt are eaten a few times a week. Red meat is limited to a few times a month. Harvard's summary also notes that moderate wine consumption — up to roughly one to two glasses daily for men and one for women — is part of the traditional pattern for those who already drink alcohol, not a recommendation to start.

Core cooking principles

The cooking methods behind the pattern are as consistent as the ingredient list. Extra virgin olive oil is the primary fat used both in dressings and in cooking, replacing butter or other saturated fats, according to Harvard's Nutrition Source. Mediterranean Living, a site focused on the diet's recipes, describes building flavor by warming olive oil at medium heat and briefly cooking aromatics such as garlic, onion and fresh herbs before adding vegetables or legumes — techniques applied across roasting, braising and sautéing. Fresh herbs like oregano, basil, dill and parsley are used to add flavor in place of excess salt, and dishes typically lean on whole, minimally processed ingredients rather than packaged or highly processed foods.

Typical traditional dishes cited by Mediterranean Living include a Greek salad of tomatoes, cucumbers, peppers, onions and olives dressed with olive oil, lemon juice and oregano; Lebanese hummus made from blended chickpeas, tahini, garlic, lemon and olive oil; and Moroccan harira, a lentil and chickpea soup seasoned with cinnamon and cumin. Vegetables and legumes form the base of most meals, with whole grains such as couscous or brown rice and modest portions of fish, poultry or cheese added rather than centered on the plate.

What the clinical evidence shows

The most-cited evidence for cardiovascular benefits comes from PREDIMED, a Spanish randomized controlled trial that enrolled 7,447 participants at high cardiovascular risk between 2003 and 2009, according to the peer-reviewed summary published on PubMed Central. Participants were assigned to a Mediterranean diet supplemented with extra virgin olive oil, a Mediterranean diet supplemented with nuts, or a low-fat control diet, with no calorie restriction or exercise program imposed. Over a median follow-up of 4.8 years, the olive oil group showed a 31% relative reduction in combined heart attacks, strokes and cardiovascular deaths, while the nut group showed a 28% reduction, both compared with the control diet.

The trial's history includes a notable correction. The original 2013 results, published in the New England Journal of Medicine, were retracted in 2018 after researchers identified protocol deviations in how some study sites had randomized participants. After excluding 1,588 participants whose assignment could not be verified as properly randomized and reanalyzing the data, the 2018 republished results were described as similar to the original findings in the PMC summary — meaning the headline risk reductions held up under the correction.

Harvard's Nutrition Source cites additional observational research linking the pattern to broader outcomes: a reported 25% lower risk of cardiovascular disease over 12 years among women who followed it closely, and a meta-analysis finding roughly 24% lower cardiovascular disease risk and 23% lower risk of premature death among higher adherers. Harvard also notes that because the diet's effects are attributed to the overall eating pattern rather than any single food, isolating one ingredient — such as olive oil alone — is not expected to reproduce the same results.

Limitations to know

Harvard's summary cautions that because the diet includes calorie-dense foods such as olive oil and nuts, it carries a risk of excess calorie intake if portions are not watched, since the plan itself does not prescribe specific serving sizes or calorie targets. Most of the supporting research, aside from PREDIMED, is observational, meaning it shows associations rather than directly proving the diet alone causes the health outcomes measured.