Health Effects of Mediterranean Diet

The Mediterranean diet is a diet inspired by the eating habits of Italy and Greece in the 1960s. 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 non-fish meat products. Olive oil has been studied as a potential health factor for reducing all-cause mortality and the risk of chronic diseases.

The Mediterranean Diet ranked #1 in Best Diets Overall. 41 diets were evaluated with input from a panel of health experts.

A 2017 re­view found ev­i­dence that prac­tice of a Mediter­ranean diet could lead to a de­creased risk of car­dio­vas­cu­lar dis­eases, over­all can­cer in­ci­dence, neu­rode­gen­er­a­tive dis­eases, di­a­betes, and early death. A 2018 re­view showed that prac­tice of the Mediter­ranean diet may im­prove over­all health sta­tus, such as re­duced risk of non-com­mu­ni­ca­ble dis­eases, re­duced total costs of liv­ing, and re­duced costs for na­tional health­care. A 2016 re­view found sim­i­lar weight loss as other diets.

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.

Cardiovascular diseases

The Mediter­ranean diet is in­cluded among di­etary pat­terns that may re­duce the risk of car­dio­vas­cu­lar diseases. A 2013 Cochrane re­view found lim­ited ev­i­dence that a Mediter­ranean diet fa­vor­ably af­fects car­dio­vas­cu­lar risk fac­tors. 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. How­ever, re­views of early 2016 have been more cau­tious: con­cerns were raised about the qual­ity of pre­vi­ous sys­tem­atic re­views ex­am­in­ing the im­pact of a Mediter­ranean diet on car­dio­vas­cu­lar risk factors, fur­ther stan­dard­ized re­search has been found to be necessary, and the ev­i­dence for the pos­si­ble pre­ven­tion of vas­cu­lar dis­ease by the Mediter­ranean diet was “lim­ited and highly variable”. 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.

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. 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 and for the con­tri­bu­tion to the main­te­nance of nor­mal blood LDL-cho­les­terol lev­els by re­plac­ing sat­u­rated fats in the diet with oleic acid (Com­mis­sion Reg­u­la­tion (EU) 432/2012 of 16 May 2012). 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. The Amer­i­can Heart As­so­ci­a­tion dis­cussed the Mediter­ranean diet as a healthy di­etary pat­tern that may re­duce the risk of car­dio­vas­cu­lar dis­eases.

Diabetes

In 2014, two meta-analy­ses found that the Mediter­ranean diet was as­so­ci­ated with a de­creased risk of type 2 diabetes, find­ings sim­i­lar to those of a 2017 review. 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.

Cancer

A meta-analy­sis in 2008 found that strictly fol­low­ing the Mediter­ranean diet was cor­re­lated with a de­creased risk of dying from can­cer by 6%. An­other 2014 re­view found that ad­her­ence to the Mediter­ranean diet was as­so­ci­ated with a de­creased risk of death from cancer. A 2017 re­view found a de­creased rate of can­cer, though ev­i­dence was weak.

Weight loss in obesity

In a 2019 re­view, the Mediter­ranean diet was dis­cussed as a di­etary pat­tern that may help obese peo­ple lower the quan­tity and im­prove the nu­tri­tional qual­ity of food in­take, with an over­all ef­fect of pos­si­bly los­ing body weight.

Cognitive ability

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.

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. 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.

Major depressive disorder

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.

Gluten

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.

Ageing

There is some ev­i­dence that a greater ad­her­ence to the Mediter­ranean diet is as­so­ci­ated with longer telom­eres.

Dietary components

The Mediterranean diet food pyramid, summarizing the pattern of eating associated with this diet
The Mediterranean diet food pyramid, summarizing the pattern of eating associated with this diet
Further information: Mediterranean cuisine
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. The “Mediter­ranean diet” as de­fined by di­eti­tians gen­er­ally in­cludes the fol­low­ing components, which are not typ­i­cal of diets in the Mediter­ranean basin:

High intakes of olive oil (as the principal source of fat), vegetables (including leafy green vegetables, onions, garlic, tomatoes and peppers), fresh fruits (consumed as desserts or snacks), cereals (mostly whole grains), nuts and legumes.
Moderate intakes of fish and other seafood, poultry, eggs, dairy products (principally 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.

In con­trast to the di­etary rec­om­men­da­tion, olive oil is not the sta­ple fat in much of the Mediter­ranean basin: in north­ern and cen­tral Italy, lard and but­ter are com­monly used in cook­ing, and olive oil is re­served for dress­ing sal­ads and cooked vegetables; in both North Africa and the Mid­dle East, sheep’s tail fat and ren­dered but­ter (samna) are tra­di­tional sta­ple fats.