Table 1.2 Estimate of the macronutrient composition of a typical MedDiet and a typical western diet (data from [9]).

Besides its typical fat composition, the MedDiet is also a rich source of a variety of carbohydrates, and these are discussed in Chapter 2. One estimate of how the overall proportions of macronutrients in a ‘typical’ western diet compare with those in a ‘typical’ MedDiet is shown in Table 1.2 [9]. This estimates MUFA intake in the MedDiet at 22% compared to 14% in a typical ‘Western’ diet. Although this analysis estimates that total PUFA intake between the two diets is similar, it should be noted that this analysis did not distinguish between n-6 and n-3 PUFAs.

Due to the high consumption of plants foods, the traditional MedDiet is a particu­larly rich source of plant chemicals (phytochemicals) and some vitamins and miner­als (see Table 1.1). One aspect of particular relevance here is that plasma folate levels have been found to be a good biomarker for adherence to the MedDiet [10]. This mainly reflects the high consumption of green leafy vegetables in the MedDiet. Folate consumption is linked to a wide range of beneficial effects in the body, including prevention of neural tube defects in early pregnancy, and protection against cancers of the pancreas, oesophagus and colon-rectum [11]. By contrast, folic acid given in supplements has been shown to promote the progression of pre-malignant colorectal lesions [12]. This illustrates the increasing evidence that micronutrient supplements may not always afford the same protective effects attributed to dietary sources. This is an important point in the debate between whole diets and the use of supplements, and is discussed further in later chapters.

Although a traditional MedDiet is still widely consumed, especially by more elderly people, the diet is now increasingly under threat. Protecting healthy tradi­tional diets against the encroaching uniformity of food, particularly the influence of fast food, is now recognised as a high priority [6]. Consequently, there was an initia­tive by Spain, Italy, Greece and Morocco to help protect the traditional MedDiet by applying for it to be adopted by UNESCO’s Intergovernmental Committee for the Safeguarding of the Intangible Cultural Heritage of Humanity [13]. The MedDiet achieved this recognition in November 2010. The box below gives the statement issued by UNESCO at the time of this recognition, and emphasises how much the MedDiet represents an overall lifestyle rather than just the consumption of food.

The current widespread interest in the MedDiet has necessitated the development of various definitions of what constitutes a ‘modern’ MedDiet. Such a definition is par­ticularly important for epidemiologists in order to be able to assess the adherence of individuals to a MedDiet [14]. Many of these epidemiological studies have been conducted in European Mediterranean countries, and hence the definitions of the MedDiet tend to reflect the traditional MedDiet of these countries [10]. One widely-used definition of the relative consumption of nine key food groups is as follows:

The use of current definitions of the MedDiet is discussed in Chapter 8, and the application of these assessments to disease prevention is considered in Chapters 10–13.

It is important to recognise that the MedDiet not only defines foods whose con­sumption is desirable, but should also encompass foods whose consumption is not desirable. This includes the absence of industrial processed foods, and is one reason for the relatively low levels of salt, saturated fat, trans fats and sugar in the MedDiet compared to the standard Western diet.

1.1.3 International differences

Despite some similarities between MedDiets, it is generally agreed that there is no one MedDiet. This is not surprising in view of the fact that Mediterranean countries are located in three different continents, namely Europe, Asia and Africa. These continents have major cultural differences, not least of which is religion: European Mediterranean countries are Christian and those in Asia and Africa are Muslim. Hence wine con­sumption, a cornerstone of the European MedDiet, is absent in Muslim countries where alcohol consumption is prohibited. There are many other differences throughout the Mediterranean basin that can influence dietary habits, and these range from climate and geography, to socio-economic factors, culture and history. These can be regional as well as international. For example, consumption of fish within a country tends to vary depending on proximity to the sea, and, at the international level, low consumption in some countries is also due to the relative scarcity of fish in some parts of the Mediterranean. Even olive oil consumption – considered another cornerstone of the MedDiet – can vary widely between Mediterranean countries. Hence, the overall types of foods can vary quite widely between various Mediterranean regions as is illustrated in Table 1.3.

The geographical boundaries within which a ‘MedDiet’ is eaten are not precisely defined. Twenty-one countries border the Mediterranean sea (although this number varies according to the definition of a national state) (Figure 1.1). The climates of these countries can vary widely from region to region, and parts of many countries that border the Mediterranean sea do not have a ‘Mediterranean’ climate in its precise climatological definition. (This is defined by climatologists as the Cs climactic region, i.e. having warm to hot, dry summers and cool, wet winters.) Even bordering the Mediterranean sea itself does not guarantee a MedDiet since parts of the coasts of Libya and Egypt do not have a Mediterranean climate. Northern Italy is another region that does not have a Mediterranean climate and correspondingly the traditional diet here is quite different to that found in Mediterranean Southern Italy. In France, only the regions of Provence, Languedoc and part of Roussillon have a Mediterranean climate, and the cuisines of other regions are quite different. By contrast, many parts of Portugal do have a Mediterranean climate, although this country is on the Atlantic seaboard and has no border with the Mediterranean sea.

A poetic, yet very useful, definition of the Mediterranean is that of the French writer Georges Duhamel who wrote: ‘The Mediterranean ends where the olive tree no longer grows’. This can be used to delineate the northern limits of ‘Mediterranean’ cuisine and is shown in Figure 1.2.

The Mediterranean climate, as defined by climatologists, is not restricted to countries of the Mediterranean region but includes parts of California, the Western Cape in South Africa, central Chile, southern Western Australia and the coastal areas of central and south-east Australia (Figure 1.3). For cultural and historical reasons, these countries did not develop a traditional MedDiet. However, their climates have allowed the production of traditional Mediterranean foods, especially grapes, and, increasingly, olives, and levels of production of traditional Mediterranean foods are increasing in these countries.

1.1.4 National representations of the MedDiet

Efforts to promote the MedDiet have led to the development of various pictorial representations. These graphics aim to convey the essentials of the MedDiet in a single glance without recourse to lengthy text, as it is considered that this could be off-putting to some people. The design of the graphic is often angled in order to appeal to the populace of a particular country.

Perhaps the best known of these pictorial representations is the food pyramid developed by the American organisation Oldways (Figure 1.4). This structure is similar to the US Food Guide Pyramid developed by the USDA. The Oldways pyramid has been refined over several versions. The base of the pyramid depicts physical activity and enjoying food with others. The remainder of the pyramid depicts the relative proportions of various foodstuffs that should be consumed, with the largest portion of the pyramid being devoted to plant foods. In addition, this 2009 version includes herbs and spices for the first time, although wild greens are not included, perhaps because their collection is not a traditional part of food culture in industrialised countries such as the US. Fish and shellfish have a prominent position, with lesser amounts of poultry and dairy produce. No distinction is made between dairy produce from cow milk (uncommon in the traditional MedDiet) and milk from goats and sheep, although cheese and yogurt are depicted and milk is excluded, and this is consistent with a traditional MedDiet. Meats and sweets are simply advised to be eaten ‘less often’. Wine in moderation and water are also shown.

Table 1.3 Important food groups in Mediterranean regions (from [15]). With permission from Elsevier.

Figure 1.1 Countries of the Mediterranean Basin (Wikipedia).The countries bordering the Mediterranean sea are (with semi-autonomous countries): Gibraltar, Spain, France, Monaco, Italy, Slovenia, Croatia, Bosnia & Herzegovina, Albania, Greece, Turkey, Cyprus, Syria, Israel, Lebanon, Egypt, Libya, Malta, Tunisia, Algeria, Morocco.

Figure 1.2 The Mediterranean region as defined by the northern limits of olive cultivation (black line) and climate (hashed areas) [1]. With permission from John Wiley & Sons.

Figure 1.3 Regions of the world with a Mediterranean climate (Wikipedia).

Figure 1.4 The Oldways’ pyramid depiction of a MedDiet [16]. Reproduced with permission. © 2009 Oldways Preservation & Exchange Trust, www.oldwayspt.org

Nutritionists in Mediterranean countries may not necessarily consider (Egyptian) pyramids to be the most appealing depiction of the MedDiet for their populaces, so they have developed images more representative of their own countries. Greek nutritionists have come up with the idea of seven Greek columns, each column showing the food to be consumed – in words rather than images – on one day of the week [17]. The basic principles of a healthy way of life, ‘moderation, variety and proportionality’, are also mentioned, together with having a correct energy balance. Italian nutritionists have developed the historical theme by turning the Greek column into a Greco-Roman temple, an apparent attempt to capitalise on the idea that a temple symbolises ‘healthiness, spirituality and self-improvement’ [18]. In this Italian model, the steps of the temple convey a healthy lifestyle, the need for adequate exer­cise, and to use virgin olive oil and to drink wine in moderation. The columns of the temple represent desirable food groups, and foods that should only be consumed in limited amounts are shown at the top of the temple. A practical weekly guide has also been developed for French consumers [19] and this is discussed fully in Chapter 14.

Figure 1.5 The Food Standards Agency Eatwell plate (http://www.eatwell.gov.uk/healthydiet/eatwellplate/). © Crown copyright material 2007, with permission from the Controller of HMSO and Queen ’ s Printer for Scotland.

It is interesting to compare these representations of the MedDiet with a current pictorial representation of UK dietary guidelines as promoted by the UK Food Standards Agency (FSA) – the so-called ‘Eatwell Plate’ (Figure 1.5). Although there are some similarities, there are also significant differences. Fruits, vegetables and carbohydrates all feature prominently on the Eatwell Plate, and this is similar to the representations of the MedDiet. Dairy products (from cow milk) are a more prominent feature on the Eatwell Plate than on the MedDiet depictions, reflecting a long tradition of dairy farming and dairy consumption in the UK. No distinction is made on the Eatwell Plate between the relative proportions of meat and fish to be consumed. Cakes and biscuits represent a relatively large slice of the Eatwell plate. Although these are also depicted on some of the MedDiet graphics, in the MedDiet these products are likely to be based on fruit, honey, nuts and olive oil, whereas inthe UK there will be a far higher content of refined sugar and saturated fat. Olive oil and wine are absent from the Eatwell Plate.

1.1.5 Sources of information for the general public

Mediterranean restaurants and cookery books

Tourism has had a major impact on the appreciation by North Europeans of Mediterranean cuisine, not to mention Mediterranean wines. There are now a plethora of Mediterranean restaurants in most towns. Elizabeth David pioneered home cook­ing of Mediterranean food in the UK with the publication of her book A Book of Mediterranean Food in 1950. It remains in print to this day. Many other Mediterra­nean cookery books are now available and some, such as those by Claudia Roden on Middle Eastern cookery and those by Clifford A. Wright, are scholarly works and include authentic recipes. There is, however, very little information on whether or not cookery books promote a healthier lifestyle. In the case of Mediterranean cookery books, most do not give a clear indication of the relative proportions of different foods that should be eaten – a fundamental aspect of healthy eating. Some books emphasise recipes using ingredients readily available to the non-Mediterranean cook rather than being truly representative of local Mediterranean cooking. In particular, MedDiet cookery books often include a relatively high proportion of recipes that contain meat, and this is not representative of a traditional MedDiet.

MedDiet organisations

There are several organisations that promote the MedDiet, and these have useful websites. The Mediterranean Diet Foundation (La Fundación Dieta Mediterránea, FDM) is a non-profit organisation based in Barcelona, Spain which promotes the investigation and dissemination of the MedDiet and the Mediterranean lifestyle. It organises conferences, runs courses, and organises a range of workshops with a particular focus on children and the elderly. Its website is at http://www.fdmed.org. Oldways is an American non-profit organisation that was responsible for developing the best-known of the Mediterranean diet food pyramids (see above). It promotes the MedDiet through conferences, events and has introduced the ‘Med Mark’ in the US to help guide consumers in choosing traditional Mediterranean foods, drinks and other products. They have a website at http://www.oldwayspt.org.

1.2 Lifestyle factors

“We do not sit at table only to eat, but to eat together.”

(Plutarch)

The traditional MedDiet, and its health benefits, cannot be fully understood without considering its cultural context. The ‘Mediterranean food culture’ (or ‘Mediterra­nean lifestyle’ as it is sometimes known) includes factors such as fixed meal times, eating as part of a social gathering and – in some countries – taking a siesta after the midday meal. Other lifestyle factors such as physical activity, not smoking, and low levels of stress have also been found to contribute to the overall health benefits of a MedDiet [20–22]. If one considers ‘diet’ in terms of its original meaning of ‘a mode of living’ from the Greek diaita, then the term ‘Mediterranean diet’ is completely congruous when implying the overall Mediterranean lifestyle.

Table 1.4 Breakfast ingredients in Mediterranean countries (adapted from [23]). With permission from Elsevier.

The central part played by food in daily Mediterranean life is reflected in the care with which local, seasonal ingredients are sourced from respected producers and the care given to preparation and cooking. Producers themselves often sell their produce at local Mediterranean markets, and this promotes a close relationship between the consumer and the producer. This relationship helps maintain the quality of the produce and ensures that good agricultural practices are used, practices that can have a major impact on the nutritional value of the food (see Chapter 3).

1.2.1 Meal patterns

Meals are still an integral part of daily society in most Mediterranean countries, and the main meal is an important opportunity for bringing family members together. Lunch is still the main meal for many Mediterranean people, and many go home for lunch whenever possible, especially in Southern and Eastern countries [23]. However, the evening meal is increasingly becoming the main meal in regions where people work through the day or who work too far away from home to return there for lunch [23]. Breakfasts tend to be light compared to North European countries (Table 1.4), both in terms of quantity and in the low consumption of produce with high levels of saturated fats such as butter, sausages and bacon that typify the tradi­tional English breakfast.

There is evidence that eating at fixed times during the day, and the associated periods when meals are not consumed, is important for inducing satiety which discourages excessive calorie intake [24]. This does not exclude the occasional consumption of snacks in traditional MedDiets (see Table 1.5), but whereas snacks in Northern Europe are a major source of salt, sugars, and saturated and trans fats [25], snacks in Mediterranean countries mostly consist of either fruit, nuts or home-made delicacies.

Table 1.5 shows a weekly food pattern collated from Cretans eating a traditional diet. During the week, the meal that included the main daily source of protein was mostly lunch, and this may particularly benefit physically active people, since studies have shown that optimal muscle building occurs when protein is eaten immediately after exercise [26]. By contrast, dinners were mainly based on easily digested cooked vegetables.

Table 1.5 Typical foods in a traditional Cretan Mediterranean diet consumed over a week [27], With permission from Elsevier.

1.2.2 Siestas

A siesta after a midday meal is still common in many Mediterranean countries. In Spain, most siestas were found to last for less than an hour. In a large study of healthy Greek men and women, working men who took a siesta were found to have fewer coronary deaths than those who did not nap [28].¹ The authors of this study suggested that regu­lar siestas acted as a stress-reducing habit, which lowered the risk for CVD [28]. Not all studies, however, have found an inverse association between siestas and coronary deaths; indeed some studies have found a positive association. Taking a siesta is not conducted in a vacuum, and interpreting the data from some of these studies is subject to possible confounding factors. For example, people taking a siesta may take less physical exercise, which is a protective factor against CVD, and hence could give rise to a positive associa­tion between taking a siesta and CVD. Also, some individuals sleep during the day due to nightly sleep disturbances, which could be associated with underlying health prob­lems. The Greek study did attempt to control for these possible confounding factors, although more studies examining the possible benefits of a siesta would be useful.

1.2.3 Physical activity

The high level of physical activity of the traditional Mediterranean peasant contrasts with the far more sedentary lifestyle of most present-day Mediterranean people. Despite this modern trend, the clement Mediterranean climate does still favour an outdoor lifestyle and more physical activity than is the case for many people living in more northern climates. In the HALE project, which evaluated the effects of a Mediterranean diet and lifestyle factors on mortality in elderly European men and women, physical activity was associated with a lower risk of all-cause mortality [22]. Increasing evidence is demonstrating that the health benefits of diet interact with other lifestyle factors, and physical exercise is now widely accepted to be an important factor that reduces the risk of age-related diseases such as CVD and some cancers [29]. A detailed study of Spanish children found that physical fitness is very important to reduce the risk of CVD and other diseases in later life, a point emphasised in the title of the paper: ‘A Mediterranean diet is not enough for health’ [30].

1.2.4 Sunshine

That Mediterranean countries are sunny is accepted almost without thought. But it has been argued that by inducing endogenous synthesis of vitamin D, sunlight is an impor­tant contributor to the health of Mediterranean people [31]. This proposal is based on recent evidence that the role of vitamin D in the body extends well beyond its role in bone health by preventing rickets and osteoporosis, and may also include a reduction in the risk for some cancers, hypertension and some immunological disorders (see Chapter 2).

1.3 Health benefits

There is a substantial body of epidemiological evidence for the health benefits of the MedDiet, and this is discussed fully in Chapters 10–13. A useful meta-analysis of a number of epidemiological studies generated the following estimates for the protective value of the MedDiet [32]:

• overall mortality reduced by 9%
• mortality from CVD reduced by 9%
• incidence of or mortality from cancers reduced by 6%
• incidence of Parkinson’s disease and Alzheimer’s disease by 13%

Other epidemiological studies show that there is some protection from other disorders including obesity, diabetes and metabolic syndrome [33], and these studies are also discussed in later chapters. Protection against CVD and cancers is the most significant in terms of reducing overall mortality.

The precise composition of the MedDiet that contribute to these protective effects continues to be an area of intense research interest. Key nutrients of the MedDiet that are thought to contribute to its beneficial effects include:

• high levels of MUFAs provided by olive oil
• high levels of PUFAs, especially n-3 fatty acids
• low levels of SFAs, and no TFAs from industrial sources
• high levels of plant-derived substances (including fibre, phytochemicals and vitamins)

A wide range of biologically plausible mechanisms has been elucidated that can explain how particular nutrients in the MedDiet may be protective against various disorders. This is a major theme of this book, and the evidence is discussed in later chapters.

1.3.1 Mediterranean dietary patterns

There is currently much interest in the relative health benefits of whole dietary patterns compared to individual dietary components [34, 35]. Although epidemiological studies can in some cases identify health benefits for individual foodstuffs, these studies do not give the complete picture. Rather, epidemiological evidence suggests that whole dietary patterns, such as a Mediterranean dietary pattern, should be considered for disease prevention, and that any one component is by itself insufficient to provide optimal health benefits [36–38]. For example, analysis of the Greek EPIC cohort found that adherence to a traditional Mediterranean diet was associated with a significantly reduced incidence of overall cancer, although there was not a statistically significant benefit simply from high consumption of fruits and vegetables [36]. This suggests that the overall dietary pattern was important in this study.

Figure 1.6 shows a comparison between the dietary patterns of Greece and the UK [39]. Compared to the UK, the Greek diet had a higher average consumption of olive oil, fruits, nuts and vegetables (although potatoes and red meat were also relatively high indicating a move away from a traditional MedDiet by the time of this 1999 analysis).

Clearly, the importance of the effect associated with a dietary pattern means that many dietary foodstuffs in this pattern may interact in a positive manner. In relation to CVD, this perspective has been summed up as follows: ‘It is very likely that the ideal combination of the different dietary components with all the possible interactions and synergy is able to produce a maximum beneficial effect on all or, at least, the majority of mechanisms linking diet and cardiovascular disease, resulting in an enhanced reduction of cardiovascular disease risk’ [40].

Figure 1.6 Dietary patterns of (a) Greece and (b) the UK in 1999 [39]. The reference circle of radius 100% indicates the mean for the Data Food Networking project (DAFNE) (absolute values are shown in brackets), and the second set of points indicates the % deviation of the food group from the reference DAFNE mean. Reprinted with permission from Macmillan Publishers Ltd, copyright 2006 Nature.

There are a plethora of candidate molecules that could contribute to the overall benefit of a traditional Mediterranean dietary pattern. However, establishing which molecules are involved is no trivial matter. A good illustration of the challenges that must be confronted is the estimate that up to 10,000 phytochemicals and their breakdown products may be consumed as part of a diet rich in vegetables [41]. Elucidating the underlying mechanistic basis for synergistic protection between such a large number of potentially active dietary components represents a major challenge as there are clearly many potential opportunities for synergistic interactions between these phytochemicals [42]. An illustration of the possible complexities is that over 1600 com­pounds have been identified in grapes, of which only a fraction have been studied in any detail [43]. Extending this to the overall MedDiet greatly amplifies the possible number of interactions between constituents in the different foods and their metabolic products.

1.3.2 Endorsements

Several health bodies have now endorsed the MedDiet. These endorsements have been prompted not only because of the well-established health benefits of the MedDiet, but also because people enjoy eating a MedDiet and so show a high degree of com­pliance when asked to maintain this dietary pattern over a period of time. In relation to CVD, there is evidence that the MedDiet is useful not only for primary prevention, but may also be beneficial for secondary prevention (i.e. after a first episode) of CVD [40]. Both the American Heart Association (AHA) and British Heart Foundation (BHF) have given endorsements of the MedDiet. The AHA Science Advisory and Coordinating Committee stated that ‘it would be short-sighted not to recognize the enormous public health benefits that the Mediterranean-style diet could confer’ [44]. The British Heart Foundation in one of its leaflets (2/99) states that ‘Positive advice to eat more fish, fruit and vegetables or to eat a more Mediterranean diet rather than simply recommending a reduction in saturated fat may be more effective at reducing mortality in patients with existing coronary heart disease’. And The British Dietetic Association also specifically recommends the MedDiet for people with coronary vascular disease or who have had a heart attack [45].