Mediterranean Diet

mediterranean diet

wine

The Mediterranean diet is a modern nutritional recommendation inspired by the traditional dietary patterns of southern Italy, Greece, and Spain. The principal aspects of this diet include proportionally high consumption of olive oil, legumes, unrefined cereals, fruits and vegetables, moderate to high consumption of fish, moderate consumption of dairy products (mostly as cheese and yogurt), moderate wine consumption, and low consumption of meat and meat products.

Despite its name, this diet is not typical of all Mediterranean cuisine. In Northern Italy, for instance, lard and butter are commonly used in cooking, and olive oil is reserved for dressing salads and cooked vegetables. In North Africa, wine is traditionally avoided by Muslims. In both North Africa and the Middle East, sheep’s tail fat and rendered butter (samna) are the traditional staple fats, with some exceptions.

The most commonly understood version of the Mediterranean diet was presented, among others, by Dr Walter Willett of Harvard University’s School of Public Health from the mid-1990s on. Based on ‘food patterns typical of Crete, much of the rest of Greece, and southern Italy in the early 1960s,’ this diet, in addition to ‘regular physical activity,’ emphasizes ‘abundant plant foods, fresh fruit as the typical daily dessert, olive oil as the principal source of fat, and fish and poultry consumed in low to moderate amounts, zero to four eggs consumed weekly, red meat consumed in low amounts, and wine consumed in low to moderate amounts.’ Total fat in this diet is 25% to 35% of calories, with saturated fat at 8% or less of calories.

Olive oil is particularly characteristic of the Mediterranean diet. It contains a very high level of monounsaturated fats, most notably oleic acid, which epidemiological studies suggest may be linked to a reduction in coronary heart disease risk. There is also evidence that the antioxidants in olive oil improve cholesterol regulation and LDL cholesterol reduction, and that it has other anti-inflammatory and anti-hypertensive effects. Although it was first publicized in 1945 by the American doctor Ancel Keys stationed in Salerno, Italy, the Mediterranean diet failed to gain widespread recognition until the 1990s. Objective data showing that Mediterranean diet is healthy first originated from the Seven Countries Study.

Mediterranean diet is based on what from the point of view of mainstream nutrition is considered a paradox: that 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. The Mediterranean diet is also high in salt content. Foods such as olives, salt-cured cheeses, anchovies, capers, salted fish roe, and salads dressed with extra virgin olive oil all contain high levels of salt. A diet rich in salads was promoted in England during the early Renaissance period by Giacomo Castelvetro in ‘A Brief Account of the Fruits, Herbs and Vegetables of Italy.’ He attempted, without success, to convince the English to eat more fruits and vegetables.

Dietary factors are only part of the reason for the health benefits enjoyed by certain Mediterranean cultures. A healthy lifestyle (notably a physically active lifestyle or labor is also beneficial. However, on the population level, i.e. for the population of a whole country or a region, the influence of genetics is rather minimal, because it was shown that the slowly changing habits of Mediterranean populations, from a healthy active lifestyle and Mediterranean diet to a not so healthy, less physically active lifestyle and a diet influenced by the Western pattern diet, significantly increases risk of heart disease. There is an inverse association between adherence to the Mediterranean diet and the incidence of fatal and non fatal heart disease in initially healthy middle aged adults in the Mediterranean region.

The putative benefits of the Mediterranean diet for cardiovascular health are primarily correlative in nature; while they reflect a very real disparity in the geographic incidence of heart disease, identifying the causal determinant of this disparity has proven difficult. The most popular dietary candidate, olive oil, has been undermined by a body of experimental evidence that diets enriched in monounsaturated fats such as olive oil are not atheroprotective when compared to diets enriched in either polyunsaturated or even saturated fats.

A recently emerging alternative hypothesis to the Mediterranean diet is that differential exposure to solar ultraviolet radiation accounts for the disparity in cardiovascular health between residents of Mediterranean and more northerly countries. The proposed mechanism is solar UVB-induced synthesis of Vitamin D in the oils of the skin, which has been observed to reduce the incidence of coronary heart disease, and which rapidly diminishes with increasing latitude. Interestingly, residents of the Mediterranean are also observed to have very low rates of skin cancer (which is widely believed to be caused by over-exposure to solar UV radiation); incidence of melanomas in the Mediterranean countries is lower than in Northern Europe and significantly lower than in other hot countries such as Australia and New Zealand.

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