The Mediterranean diet is a concept first invented in 1975 by the American biologist Ancel Keys and chemist Margaret Keys. The diet took inspiration from the supposed eating habits and traditional food typical of Crete, much of the rest of Greece, and southern Italy, 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]
The Mediterranean diet is included among dietary patterns that may reduce the risk of cardiovascular diseases. [10] A 2013 Cochrane review found limited evidence that a Mediterranean diet favorably affects cardiovascular risk factors. [16] A 2013 meta-analysis compared Mediterranean, vegan, vegetarian, low-glycemic index, low-carbohydrate, high-fiber, and high-protein diets with control diets. The research concluded that Mediterranean, low-carbohydrate, low-glycemic index, and high-protein diets are effective in improving markers of risk for cardiovascular disease and diabetes, while there was limited evidence for an effect of vegetarian diets on glycemic control and lipid levels unrelated to weight loss. [18] However, more cautious reviews arose in early 2016, raising concerns about the quality of previous systematic reviews examining the impact of a Mediterranean diet on cardiovascular risk factors. [19] These reviews insisted upon the need for further standardized research, [20] stating that the evidence for possible prevention of cardiovascular disease by the diet was "limited and highly variable". [21] Reviews in 2016-17 reached similar conclusions about the ability of a Mediterranean diet to improve cardiovascular risk factors, such as lowering the risk for hypertension and other cardiovascular diseases. [9] [22] A Mediterranean diet is recommended as a means of lowering Apolipoprotein B. [23]
The Mediterranean diet is low in saturated fat with high amounts of monounsaturated fat and dietary fiber. One possible factor is the potential health effects of olive oil in the Mediterranean diet. Olive oil contains monounsaturated fats, most notably oleic acid, which is under clinical research for its potential health benefits. [24] The European Food Safety Authority Panel on Dietetic Products, Nutrition and Allergies approved health claims on olive oil, for protection by its polyphenols against oxidation of blood lipids [25] and for the contribution to the maintenance of normal blood LDL-cholesterol levels by replacing saturated fats in the diet with oleic acid [26] (Commission Regulation (EU) 432/2012 of 16 May 2012). [27] A 2014 meta-analysis concluded that an elevated consumption of olive oil is associated with reduced risk of all-cause mortality, cardiovascular events and stroke, while monounsaturated fatty acids of mixed animal and plant origin showed no significant effects. [28] The American Heart Association discussed the Mediterranean diet as a healthy dietary pattern that may reduce the risk of cardiovascular diseases. [29]
A 2023 review found evidence for a reduction of mortality and cardiovascular disease risk in women on a Mediterranean-type diet. [30]
In 2014, two meta-analyses found that the Mediterranean diet was associated with a decreased risk of type 2 diabetes, [31] [32] findings similar to those of a 2017 review. [9] The American Diabetes Association and a 2019 review indicated that the Mediterranean diet is a healthy dietary pattern that may reduce the risk of diabetes. [33] [34]
A meta-analysis in 2008 found that strictly following the Mediterranean diet was correlated with a decreased risk of dying from cancer by 6%. [35] Another 2014 review found that adherence to the Mediterranean diet was associated with a decreased risk of death from cancer. [36] A 2017 review found a decreased rate of cancer, though evidence was weak. [9] An updated review in 2021 found that the Mediterranean diet is associated with a 13% lower risk of cancer mortality in the general population. [37]
Overweight adults who adopt Mediterranean diets may lose weight by consuming fewer calories. [38] [39] [40] A 2019 review found that the Mediterranean diet may help obese people lower the quantity and improve the nutritional quality of food intake, with an overall effect of possibly losing body weight. [10]
A 2016 systematic review found a relation between greater adherence to a Mediterranean diet and better cognitive performance; it is unclear if the relationship is causal. [41]
According to a 2013 systematic review, greater adherence to a Mediterranean diet is correlated with a lower risk of Alzheimer's disease and slower cognitive decline. [42] Another 2013 systematic review reached similar conclusions, and also found a negative association with the risk of progressing from mild cognitive impairment to Alzheimer's, but acknowledged that only a small number of studies had been done on the topic. [43]
There is a correlation between adherence to the Mediterranean diet and a lower risk of depression. Studies on which these correlations are made are observational and do not prove cause and effect. [44] [45]
As the Mediterranean diet usually includes products containing gluten like pasta and bread, increasing use of the diet may have contributed to the growing rate of gluten-related disorders. [46]
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. [47] The "Mediterranean diet" as defined by dietitians generally includes the following components, [10] which are not typical of diets in the Mediterranean Basin: [48] [49]
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. [49]
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; [50] in both North Africa and the Middle East, sheep's tail fat and rendered butter (samna) are traditional staple fats. [51]
Foods | Oldway's Preservation and Trust (2009) [53] | Mediterranean Diet Foundation (2001) [54] | Greek Dietary Guidelines (1999) [55] [56] |
---|---|---|---|
Olive oil | Every meal | Every meal | Main added lipid |
Vegetables | Every meal | ≥2 servings every meal | 6 serv./day |
Fruits | Every meal | 1–2 serv. every meal | 3 serv./day |
Bread/cereals | Every meal | 1–2 serv. every meal | 8 serv./day |
Legumes | Every meal | ≥2 serv./week | 3-4 serv./week |
Nuts | Every meal | 1–2 serv./day | 3–4 serv./week |
Fish/seafood | ≥2 serv./week | ≥2 serv./week | 5–6 serv./week |
Eggs | Moderate portions, daily to weekly | 2–4 serv./week | 3 serv./week |
Poultry | Moderate portions, daily to weekly | 2 serv./week | 4 serv./week |
Dairy products | Moderate portions, daily to weekly | 2 serv./day | 2 serv./day |
Red meat | Less often | <2 serv./week | 4 serv./month |
Sweets | Less often | <2 serv./week | 3 serv./week |
Red wine | In moderation | In moderation | Daily, in moderation |
Servings are defined as: bread 25 g., potato 100 g., cooked pasta 50–60 g., vegetables 100 g., apple 80 g., banana 60 g., orange 100 g., melon 200 g., grapes 30 g., milk or yogurt 1 cup, 1 egg, meat 60 g., cooked dry beans 100 g. |
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. [57] The environmental impact and amount of energy needed to feed livestock exceeds its nutritional value. [58] [59] 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%. [60] [61]
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), [62] 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, [63] Naples and Madrid, confirmed later by the Seven Countries Study first published in 1970, [64] and a book-length report in 1980. [65]
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. [66] [67] [68] [69] 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. [70] By 2011, the Mediterranean diet was included by some authors as a fad diet promoted for losing weight. [71]
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. [29] [72] [33] The United Kingdom's National Health Service also recommends a Mediterranean diet to reduce cardiovascular disease risk. [73] [74]
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. [75]
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Dairy products or milk products, also known as lacticinia, are food products made from milk. The most common dairy animals are cow, water buffalo, nanny goat, and ewe. Dairy products include common grocery store food around the world such as yogurt, cheese, milk and butter. A facility that produces dairy products is a dairy. Dairy products are consumed worldwide to varying degrees. Some people avoid some or all dairy products because of lactose intolerance, veganism, environmental concerns, other health reasons or beliefs.
Dieting is the practice of eating food in a regulated way to decrease, maintain, or increase body weight, or to prevent and treat diseases such as diabetes and obesity. As weight loss depends on calorie intake, different kinds of calorie-reduced diets, such as those emphasising particular macronutrients, have been shown to be no more effective than one another. As weight regain is common, diet success is best predicted by long-term adherence. Regardless, the outcome of a diet can vary widely depending on the individual.
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
Omega−3 fatty acids, also called omega−3 oils, ω−3 fatty acids or n−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond three atoms away from the terminal methyl group in their chemical structure. They are widely distributed in nature, being important constituents of animal lipid metabolism, and they play an important role in the human diet and in human physiology. The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA can be found in plants, while DHA and EPA are found in algae and fish. Marine algae and phytoplankton are primary sources of omega−3 fatty acids. DHA and EPA accumulate in fish that eat these algae. Common sources of plant oils containing ALA include walnuts, edible seeds, and flaxseeds as well as hempseed oil, while sources of EPA and DHA include fish and fish oils, and algae oil.
Type 2 diabetes (T2D), formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent urination, fatigue and unexplained weight loss. Symptoms may also include increased hunger, having a sensation of pins and needles, and sores (wounds) that do not heal. Often, symptoms develop slowly. Long-term complications from high blood sugar include heart disease, stroke, diabetic retinopathy, which can result in blindness, kidney failure, and poor blood flow in the lower-limbs, which may lead to amputations. The sudden onset of hyperosmolar hyperglycemic state may occur; however, ketoacidosis is uncommon.
A saturated fat is a type of fat in which the fatty acid chains have all single bonds between the carbon atoms. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branched chain of carbon (C) atoms. Along the chain, some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). A double bond along the carbon chain can react with a pair of hydrogen atoms to change into a single -C-C- bond, with each H atom now bonded to one of the two C atoms. Glyceride fats without any carbon chain double bonds are called saturated because they are "saturated with" hydrogen atoms, having no double bonds available to react with more hydrogen.
Low-carbohydrate diets restrict carbohydrate consumption relative to the average diet. Foods high in carbohydrates are limited, and replaced with foods containing a higher percentage of fat and protein, as well as low carbohydrate foods.
Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases, heart failure, hypertensive heart disease, rheumatic heart disease, cardiomyopathy, arrhythmia, congenital heart disease, valvular heart disease, carditis, aortic aneurysms, peripheral artery disease, thromboembolic disease, and venous thrombosis.
Hypercholesterolemia, also called high cholesterol, is the presence of high levels of cholesterol in the blood. It is a form of hyperlipidemia, hyperlipoproteinemia, and dyslipidemia.
A plant-based diet is a diet consisting mostly or entirely of plant-based foods. Plant-based diets encompass a wide range of dietary patterns that contain low amounts of animal products and high amounts of fiber-rich plant products such as vegetables, fruits, whole grains, legumes, nuts and seeds. They do not need to be vegan or vegetarian, but are defined in terms of low frequency of animal food consumption.
In biochemistry and nutrition, a monounsaturated fat is a fat that contains a monounsaturated fatty acid (MUFA), a subclass of fatty acid characterized by having a double bond in the fatty acid chain with all of the remaining carbon atoms being single-bonded. By contrast, polyunsaturated fatty acids (PUFAs) have more than one double bond.
Calorie restriction is a dietary regimen that reduces the energy intake from foods and beverages without incurring malnutrition. The possible effect of calorie restriction on body weight management, longevity, and aging-associated diseases has been an active area of research.
A healthy diet is a diet that maintains or improves overall health. A healthy diet provides the body with essential nutrition: fluid, macronutrients such as protein, micronutrients such as vitamins, and adequate fibre and food energy.
A diabetic diet is a diet that is used by people with diabetes mellitus or high blood sugar to minimize symptoms and dangerous complications of long-term elevations in blood sugar.
Many dietary recommendations have been proposed to reduce the risk of cancer, few have significant supporting scientific evidence. Obesity and drinking alcohol have been correlated with the incidence and progression of some cancers. Lowering the consumption of sweetened beverages is recommended as a measure to address obesity.
The Western pattern diet is a modern dietary pattern that is generally characterized by high intakes of pre-packaged foods, refined grains, red meat, processed meat, high-sugar drinks, candy and sweets, fried foods, industrially produced animal products, butter and other high-fat dairy products, eggs, potatoes, corn, and low intakes of fruits, vegetables, whole grains, pasture-raised animal products, fish, nuts, and seeds.
Intermittent fasting is any of various meal timing schedules that cycle between voluntary fasting and non-fasting over a given period. Methods of intermittent fasting include alternate-day fasting, periodic fasting, such as the 5:2 diet, and daily time-restricted eating.
Weight management refers to behaviors, techniques, and physiological processes that contribute to a person's ability to attain and maintain a healthy weight. Most weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. Moreover, weight management involves developing meaningful ways to track weight over time and to identify the ideal body weights for different individuals.
Frank B. Hu is a Chinese American nutrition and diabetes researcher. He is Chair of the Department of Nutrition and the Fredrick J. Stare Professor of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health, and Professor of Medicine at the Harvard Medical School.
Preventive Nutrition is a branch of nutrition science with the goal of preventing, delaying, and/or reducing the impacts of disease and disease-related complications. It is concerned with a high level of personal well-being, disease prevention, and diagnosis of recurring health problems or symptoms of discomfort which are often precursors to health issues. The overweight and obese population numbers have increased over the last 40 years and numerous chronic diseases are associated with obesity. Preventive nutrition may assist in prolonging the onset of non-communicable diseases and may allow adults to experience more "healthy living years." There are various ways of educating the public about preventive nutrition. Information regarding preventive nutrition is often communicated through public health forums, government programs and policies, or nutritional education. For example, in the United States, preventive nutrition is taught to the public through the use of the food pyramid or MyPlate initiatives.
Many factors have contributed to the development of gluten-related pathology, starting with the worldwide spread of the Mediterranean diet, which is based on a high intake of gluten-containing foods.