The Mediterranean Diet: An Evidence-Based Approach

By Victor R Preedy and Ronald Ross Watson

The Mediterranean Diet offers researchers and clinicians a single authoritative source which outlines many of the complex features of the Mediterranean diet: ranging from supportive evidence and epidemiological studies, to the antioxidant properties of individual components. This book embraces a holistic approach and effectively investigates the Mediterranean diet from the cell to the nutritional well-being of geographical populations. This book represents essential reading for researchers and practicing clinicians in nutrition, dietetics, endocrinology, and public health, as well as researchers, such as molecular or cellular biochemists, interested in lipids, metabolism, and obesity.

• Presents one comprehensive, translational source for all aspects of how the Mediterranean diet plays a role in disease prevention and health
• Experts in nutrition, diet, and endocrinology (from all areas of academic and medical research) take readers from the bench research (cellular and biochemical mechanisms of vitamins and nutrients) to new preventive and therapeutic approaches
• Features a unique section on novel nutraceuticals and edible plants used in the Mediterranean region

• Language: English
• Publisher: Academic Press
• Release date: Nov 19, 2014
• ISBN: 9780124079427

Book preview

general.

Section 1

The Mediterranean Diet: Concepts and General Aspects

Chapter 1

On the Origins and Evolution of the Mediterranean Diet

Yardena Arnoni, MSc [e-mail]; Elliot M. Berry, MD, FRCP [e-mail]    Hebrew University-Hadassah Medical School, Jerusalem, Israel

Abstract

The Mediterranean diet is reviewed in the context of history and culture. The health benefits of the Mediterranean diet are scientifically recognized. The ancient Mediterranean diet focuses on the seven biblical species—wheat, barley, grapes, figs, pomegranates, olives, and date honey—together with other indigenous foods from the Middle East that radiated out of the cradle of civilization in Mesopotamia. In addition to food, lifestyle modification of the original Mediterranean tradition involves physical activity and communal meals. The Mediterranean diet is a convenient, lifestyle-friendly diet that, when fortified by its biblical attributes, may enhance health benefits and be more enjoyable and hence sustainable. Adoption of such a lifestyle may help combat the obesogenic environment and decrease the risks of the noncommunicable diseases of modern life.

Keywords

Biblical diet

Seven biblical species

Mediterranean lifestyle

Health benefits

Acknowledgment

The authors thank Dr. Sig Geller for editorial revision.

Introduction

Ample empirical evidence exists for the health benefits of the Mediterranean diet. The nutritional benefits of the foods incorporated in the modern Mediterranean diet have been well elucidated, and a plethora of literature has been published to support the claims of health and disease prevention [1]. Yet the historical and biblical origins of the Mediterranean diet remain to be emphasized. While the name itself attests to the geographical location, the composition of the original Mediterranean diet needs to be considered in its original environment. The word diet is derived from the Greek diaeta, meaning not just food but way of life. The Mediterranean diet is an interwoven, multicultural labyrinth that has developed over time, absorbing the richness of the diverse cultures of different occupiers/conquerors while maintaining original local traditions.

The term Mediterranean diet was coined in 1960 by the American physiologist Ancel Keys and his wife Margaret in their book How to Eat Well and Stay Well the Mediterranean Way [2]. They identified the eating behaviors of countries such as Greece—Crete in particular—and southern Italy, with extension to other geographical areas around the Mediterranean basin. Based on their pioneer studies, the dietary patterns of these countries were associated with longevity and reduced rates of coronary heart disease morbidity and mortality, cancers, and other chronic diseases related to diet in the 1960s [3,4]. The Mediterranean diet, however, did not begin in the 1960s but extends further back to biblical times.

Geographic and Evolutionary History

The world of the biblical Mediterranean diet covers regions of land connected to a sea and extending to an ocean. The geographic and evolutionary origins of the diet are of interest because they encompass the history of Western civilization. The rise of agriculture (domestication of crops) and animal husbandry took place from ca. 10,000 to 4000 BCE, whereas the wheel, metallurgy, writing, and city-states arose from ca. 4000 to 1000 BCE. These essential developments in the evolution of civilization originated in the Fertile Crescent: from Mesopotamia, the ancient Near East, Canaan, and Egypt. The biblical period from the time of the patriarchs until King David in Jerusalem was from ca.1950 to 1000 BCE; the fall of Troy and the Greek colonization of Ionia occurred in the twelfth century BCE and David’s capture of Jerusalem in ca. 1000 BCE.

Evidence of dietary patterns has been obtained from archaeo-botany and written records. The origins and spread of domesticated grains has been traced to the Fertile Crescent, spreading from Mesopotamia (the cradle of civilization) [5–7] (Figures 1 and 2). It seems that such food use reached the Middle East before the Greek islands. While there are many similarities between the traditional Greek (Cretan) Mediterranean diet and that described in the Pentateuch, the differences are of interest because they have special nutritional benefits. The Bible speaks of the seven species—wheat, barley, grapes, figs, pomegranates, olives, and honey—as well as a land flowing with milk and (date) honey (Deuteronomy 8:8), which are, coincidently, the basic staples of Mediterranean cuisine. In Roman times, historians recorded that the produce of the land of Israel was of particularly high quality and was served at the best tables. Such cross-cultural influences may be seen during the Last Supper, which possibly was a Passover seder and was itself adapted from the Greek symposium brought to the region after the conquests of Alexander the Great in the fourth century BCE.

Figure 1 Distribution of wild emmer ( Triticum dicoccoides ) in the Near East. Solid circles represent known sites in which wild emmer is common [ 7 ]. Reprinted with permission from Science.

Figure 2 Distribution of known and reasonably certain sites of wild barley [ 7 ]. Reprinted with permission from Science.

Origins of the Mediterranean Diet and the Biblical Diet

The strength of the Mediterranean diet is its connection to ancient biblical culture; it is not a transitional trend [8]. The origin of the Mediterranean diet encompasses the history of Western civilization. In its traditional form, the food in the region was eaten according to the season, dictated by climate and agriculture and over and above commemoration of landmarks such as annual festivals.

Countries were influenced by factors of religion and tradition, economics and foreign governing powers. Eating in the Mediterranean culture surpasses the indispensable consumption of calories for energy. The social element of eating elevated meals to become more than just a means of fulfilling biological (animal) instincts: We do not sit at the table only to eat, but to eat together (quote attributed to Plutarch, 46–120 CE). On some occasions meals had a religious status, as seen in the Jewish Sabbath, New Moon, and festival meals. These feasts were of extended duration, with special ritual foods to mark the occasions. The dietary laws of the Bible forbade mixing milk with meat (Exod. 23:19 and 34:26; Deut. 14:21) and proscribed eating pig and shellfish, allowing only animals with a cloven hoof and that chewed the cud (Lev. 11:3), while fish had to have both fins and scales (Lev. 11:9). The reasons for this are not clear but might relate to eating only those animals that were preyed upon and not predators.

Meat is neither common nor outlawed in the ancient Mediterranean diet. In biblical times, meat was generally eaten only on special occasions, and in later Christian tradition lamb was part of the Easter meal. In the Jewish religion the law institutes certain obligations and duties regarding the consumption of animals. The animal is killed without suffering by a trained authority. Blood cannot be consumed; only ruminant mammals and certain birds are deemed kosher. In the Christian tradition, the New Testament put an end to the Jewish prohibitions on food but maintained the ritual of avoiding gluttony and greed. In Islam certain prohibitions related to meat (including not eating pork) are enforced for it to be ordained Halal and suitable for consumption, whereas wine is forbidden.

In the biblical land flowing with milk and (date) honey the seven species (Exod. 3:8) were given high priority. Archeological excavations have uncovered these products eaten during the Minoan period and dating back to the Bronze Age civilization that arose on the island of Crete (2700–1450 BCE). Before this, in the Copper Age, plants and food from the sea were almost the sole sources of nutrients.

Mediterranean Lifestyle

Human genetic profiles have not changed significantly over the past 10,000 years, whereas lifestyle has been revolutionized. Modern industrialized populations are characterized by reduced energy expenditure and increased energy intake. Fat intake in the form of trans and saturated fats has increased, and there is a decreased intake of fiber, complex carbohydrates, fruits and vegetables (vitamins and antioxidants), protein, and calcium [9]. In the United States there were three times more deaths due to cancer and coronary heart disease than in Crete [10], and this differential has only been increasing. The Lyon Heart Study adapted the Cretan diet for the French population and showed cardioprotective and anticancer effects, thereby demonstrating that the Mediterranean diet can be modified to suit other populations [11]. Current trends of eating while watching television promote unhealthy, quick meals and exclude social/family communication. Other factors that may contribute to the Mediterranean lifestyle include a relaxing psychosocial environment, mild climate, preservation of the extended family structure, and even a siesta [12], as well as regular activity, mainly through walking [13]. Sleep and exercise deficiencies have been correlated with chronic illnesses such as diabetes and heart disease [14].

Components of the Original Mediterranean Diet

A homogeneous Mediterranean diet is hard to deduce; each Mediterranean country brings its unique culture, history, and tradition to its food and eating. Diversity notwithstanding, Mediterranean regions share certain common dietary practices that remain a firm foundation for the food consumed that is responsible for health benefits. The Keys’ research highlighted the three primary components of the Mediterranean diet: olive oil, wine, and bread. The generic Mediterranean diet is characterized by a high monounsaturated fat-to-saturated fat ratio, low total fat (< 30%), low saturated fat (< 10%), moderate alcohol intake (essentially wine), and high intake of vegetables, fruits, legumes, and grains (complex carbohydrates and dietary fiber) [15]. Contemporary adjustments in the Mediterranean cuisine have occurred as a result of new products and influences stretching from Asia to America with the introduction of tomatoes, potatoes, cornbeans, and cane and sugar, which, while widespread in modern cuisine, are not native to the region. The following sections describe the health benefits of different components of the biblical diet in addition to the conventional Mediterranean diet recommended today.

The Biblical Seven Species

The biblical seven species—wheat, barley, grapes, figs, pomegranates, olives, and date honey—together with some indigenous foods from the Middle East, are now scientifically recognized as healthy foods, and the addition of some of these could further enhance the benefits of the Mediterranean diet. Tables 1 and 2 detail some of the biblical and historical references to the seven species.

Table 1

Some Selected Biblical References to Fruits and Vegetables in the Mediterranean Diet

Table 2

Some Selected Biblical References to Grains in the Mediterranean Diet

Grains

The pivotal role of bread is further emphasized by its important status and use during festivals. In the tenth century BCE, carvings on limestone describe the harvest seasons in the land of Israel according to the Gezer calendar, which is a rhythmic enumeration of the agricultural seasons. In the dry summer months vines were pruned; figs, dates, pomegranates, and grapes ripened; and the wheat was harvested, whereas in the spring season barley was harvested. Wheat flour and grain have provided the staple (breads, pitas, etc.) for different types of meals throughout the Mediterranean basin. Fresco wall paintings at Knossos show the prime role of bread in the Cretan diet. It is the basic food, par excellence, and is at the center of food culture in addition to its great religious meaning and social value. Cereals include wheat, barley, rye, spelt, and oats. Barley, as opposed to wheat, contains little gluten, is coarse, and is tough to chew. The method of preparation of grains was inventive, including kneading, fermenting, drying, baking, and cooking. Means of consumption were diverse: leavened or unleavened bread, cornmeal (Italian polenta), and porridge (Spanish gachas), semolina, and pasta [16]. The process of bread production in ancient times was an intense, complex process that differentiated between domesticated man and the nomad.

Olives

The olive in the form of fruit and its derivative, olive oil, is arguably the primary element of the Mediterranean diet, maintaining its position from biblical to modern times. Definitions of the Mediterranean basin have even been ascribed to regions where olive trees grow. When saturated fats are replaced with monounsaturated fats in the human diet, plasma cholesterol concentrations improve [17]. In murine models of atherogenesis, the most impressive beneficial effect is shown for extra virgin oil enriched with green tea polyphenols [18].

In ancient times olives were consumed by farmers and carried by travelers and nomads; furthermore, olives were a popular appetizer. Romans served olives as starters and desserts in their rich banquets. The majority of fat in olive oil contains monounsaturated fatty acids. Fat from edible olives and olive oil consists of oleic acid [c18:1, n − 9] (75%), saturated fat (15%), and polyunsaturated fat (10%). Olive oil is extracted from deeply pigmented olives that are rich in phytonutrients, including the phenolics hydroxytyrosol and oleorupein.

In biblical times, olive oil was cold pressed and stored in dark, opaque glass containers as a means to protect the taste from what is now known as the powerful oxidative action of sunlight. Unprocessed olive oil has the greatest antioxidant effect. Comparison of extracted phenolic compounds from extra virgin olive oil and processed olive oil showed that extra virgin olive oil has significantly greater antioxidant effects than processed olive oil [19]. The unprocessed extra virgin olive oil of the biblical diet had a higher concentration of antioxidants, which may prevent low-density lipoprotein (LDL) oxidation. In addition to the advantageous effects on blood cholesterol, olive oil also has anticarcinogenic actions [20]. It seems, therefore, that some of the phenolic content and health benefits are reduced during the modern process of olive oil refinement.

Dates

In the Persian Gulf, going back to biblical days, dates have remained a prominent source of sweetness in the Mediterranean cuisine. The date was a convenient source of nutrients for nomads and travelers. Fruits of the date palm (Phoenix dactylifera L. arecaceae) are an important dietary component in the Middle East and north Africa. Dates are an ideal high-energy food because they contain high sugar content. They are also a good source of fiber and minerals such as calcium, iron, magnesium, potassium, and zinc [21]. Date fruit is used in folk medicine for the treatment of various infectious diseases and cancer [22] because of the apparent immunomodulatory activity [22], antibacterial capacity [23], and antifungal properties that have become evident with use [24]. Furthermore, aqueous extracts of dates have been shown to have potent antioxidant activity [25], since they inhibit in vitro lipid and protein oxidation, and possess substantial free radical scavenging capacity.

Pomegranates

The pomegranate has been cultivated in the Mediterranean region since ancient times and was introduced into Egypt from Syria and from Israel around 1600 BCE. In the Bible, the coat of the high priest was adorned with pomegranates (Exod. 39:34–26). There are many quotations concerning this luscious fruit, especially in the Song of Songs: As a piece of pomegranate are thy temples (6:7); I would cause thee to drink of spiced wine and the juice of my pomegranate (Song of Sol. 8:2). In Greek mythology, the pomegranate was a symbol of life and rejuvenation. It has potent antioxidants, including ellagitannin polyphenolic compounds such as punicalagins and punicalins, as well as ellagic acid and gallic acid. Pomegranates have been shown to reduce LDL oxidation [26] and to decrease the progression of prostate cancer [27]. Furthermore, drinking just 50 mL of pomegranate juice daily for 3 months can significantly lower blood pressure by 5%. Pomegranate is a major source of most potent antioxidants (tannins, anthocyanins), and leaf extracts from pomegranate may also be effective in weight loss since pomegranate consumption reduces fat absorption from the intestine without affecting plasma triglycerides concentrations and is a potent nutraceutical agent against cardiovascular disease [28,29].

Figs

The fig is the fruit of lust and is believed to be an omen for fertility. The large amount of fiber in figs stimulates bowel movement. Excavations at Gezer uncovered remains of dried figs from the Neolithic Age, and an old seed was germinated recently from a deposit near the Dead Sea [30]. Figs are native to the Mediterranean, growing on the ficus tree (Ficus carica), and were one of the first fruits to be cultivated. The fruit is rich in sucrose and simple sugars, minerals, and fibers and is a good source of potassium, calcium, magnesium, iron, copper, and manganese. Dried figs are popular because they last for a long time and have a high calcium content (250 mg calcium/100 g dried fruit weight).

Grapes

Vine cultivation and wine production originated in Mesopotamia. The culture of wine consumption, however, belongs to the Mediterranean. An Egyptian inscription from 2375 BCE records how a military governor, Uni, sent troops to put down a revolt in Israel during the reign of Pharaoh Pepi I and how they destroyed the fortresses… and felled the fig trees and vines. A mural from the reign of Amenopsis II (fifteenth century BCE) shows the preparation of wine in Egypt by the Apirou, considered by some to be a reference to the Hebrews [31]. From early Egyptian civilization through the times of the Roman Empire, wine has been of importance, especially to the civilized elite. Consumption of wine in the Mediterranean diet is subject to different cultural norms, especially in Muslim countries that prohibit wine intake. Hence, during the period of Arab rule, vineyards in occupied regions deteriorated.

Red wine is rich in antioxidants from the flavonoid phenolics family, including cathechin, querchitin, anthocyanins, and resveratrol. Resveratrol is a trihydroxystilbene phenolic compound found in grape seeds and skins, and it was shown to increase blood high-density lipoprotein cholesterol, to protect against LDL oxidation, and to attenuate blood clotting [32]. Resveratrol has been reported to have antiaging effects and be protective against carcinogenesis [33].

In the Mediterranean culture, wine is consumed as part of a meal, whereas Western cultures may consume wine independent of meals. Alcohol consumption unaccompanied by food leads to rapid alcohol absorption and increases the risk of intoxication. It is of interest that the Rambam (Maimonides) noted the health benefits of wine more than 800 years ago [34].

The lower antioxidant activity of white wines compared to red wines lies in the reduced amount of polyphenols extracted from the grape skin; red wine is prepared after spending a long time (~ 1 month) in contact with the grape skin. The potent antioxidant activity of an Israeli red wine also was demonstrated in a study of a UK wine, where the antioxidant capability of the UK wine was lower than that of the Israeli wine. Flavonols are potent polyphenolic antioxidants, and this may explain the above results. There is wide variation in the flavonol content of different red wines throughout the world, and the amount of sunlight to which the grapes are exposed during cultivation, when flavonols are synthesized, is a major determinant of production of flavonols in grapes. Thus, the climatic conditions under which grapes are grown could explain the fivefold increased content of flavonols in and the higher antioxidant potency of the specific Israeli red wine studied compared to the UK wine [35].

Additional Biblical Foods

The Mediterranean diet, particularly that from Crete, has a balanced intake of polyunsaturated essential fatty acids—omega 6 and omega 3—in a ratio of 2:1, in contrast to the much higher ratios observed in the diets of western and northern Europe and the United States [9]. In the traditional Mediterranean diet a sweet tooth was satisfied by intake of carobs and figs stuffed with walnuts as a snack.

Carob

During the Roman persecution, Rabbi Shimon Bar Yochai and his son survived, according to tradition, for 13 years in a cave by eating carobs and dates and drinking water [36]. Carob is a legume native to the Mediterranean. The word carob is derived from the Arab kharrub and means pod; it also gave the name carat to the measure of gold. Carob beans can be dried, ground, and roasted to produce carob flour or powder. Carob is caffeine free and naturally sweet; it is a rich source of calcium and potassium and smaller amounts of iron and some B vitamins. Insoluble fiber extracted from carob pulp has been shown to have beneficial effects, lowering LDL cholesterol and triglycerides [37].

Nuts

Nut consumption has an inverse relationship with risk for cardiovascular diseases [38]. Nuts are rich in protein, fiber, phytonutrients, and polyphenolic antioxidants, as well as monounsaturated fatty acids and polyunsaturated fatty acids. Walnuts in particular have a high content of omega 3 fatty acids, in addition to high amounts of fiber, B vitamins, magnesium, and several types of antioxidants. Walnuts are reported to be active in improving blood vessel elasticity and in reducing atherosclerotic plaque accumulation, LDL cholesterol concentration in blood, and the inflammatory C-reactive protein biomarker [39]. Peanuts were shown to contain the flavonoid resveratrol (about 70 μg per ounce of peanuts), whereas almonds contain the flavonoids quercetin and kaempferol. Nuts are a rich source of fiber, vitamin E, and phytochemicals such as ellagic acid, flavonoids, phenolics, luteolin, isoflavones, and tocotrienols. They are also an excellent source of magnesium, zinc, selenium, copper, iron, riboflavin, niacin, and folic acid.

Conclusion

Western lifestyle has penetrated Mediterranean regions, whether by a welcome invitation or via indirect diffusion through economic globalization and modern industrialization [40]. An obesogenic environment, characterized by easily available concentrated sugar and high-fat foods along with activity-reducing habits, has infiltrated the territory of the Mediterranean basin and broken the traditions of family-centered, season-orientated meals. Adoption of a food pyramid with an emphasis on traditional biblical food would be beneficial [8] (Figures 1–3). From biblical times through the centuries, the Mediterranean diet has been able to adapt and incorporate the beneficial food and customs of different foreign rules. In modern times and in the future, the role of the Mediterranean diet may be to add to its proven health benefits by incorporating biblical foods, with their respective health benefits, within the diet and lifestyle.

Figure 3 Proposed additions of biblical components to the Mediterranean diet pyramid.

Summary Points

• The Mediterranean diet is reviewed in the context of history and culture.

• The ancient Mediterranean diet focuses on the seven biblical species—wheat, barley, grapes, figs, pomegranates, olives, and date honey—together with other indigenous foods from the Middle East. These have been shown to have beneficial health properties.

• The original, traditional Mediterranean lifestyle involves physical activity and communal meals.

• Adopting such habits and including biblical foods in the Mediterranean diet will help combat the obesogenic environment and counter the risks of the noncommunicable diseases of modern life.

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Chapter 2

Nutritional Adequacy of the Mediterranean Diet

Itandehui Castro-Quezada, MSc¹,² [e-mail]; Blanca Román-Viñas, MD, PhD²,³ [e-mail]; Lluís Serra-Majem, MD, PhD¹,²,³ [e-mail]    ¹ University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.

² CIBER Fisiopatologia Obesidad y Nutrición, Instituto de Salud Carlos III, Lourdes, Spain.

³ Fundación para la Investigación Nutricional, University of Barcelona Science Park, Barcelona, Spain.

Abstract

In recent years there has been an increased interest in finding a dietary pattern that satisfies a population’s nutritional requirements. The Mediterranean dietary pattern (MDP) encapsulates a beneficial fatty acid profile with high monounsaturated fatty acids content, a low proportion of carbohydrate, and high intake of dietary fiber and antioxidant compounds that work together to produce beneficial effects on health. Greater adherence to this pattern has been related to a reduced risk of mortality and decreased incidence of cardiovascular diseases, certain types of cancer, and type 2 diabetes. Nutritional adequacy is the probability of a certain nutrient intake to be adequate for an individual and can be estimated if the requirement distribution is known. Prevalence of nutrient inadequacy in groups can be estimated by the average requirement cut-point method. However, indices or dietary patterns can also be used because they correlate considerably well with nutritional adequate intakes. The MDP has been associated on an increased probability of fulfilling nutrient recommendations. Therefore, preserving the Mediterranean diet should be encouraged in health promotion strategies instead of alternatives such as fortification and supplementation.

Keywords

Mediterranean diet

Dietary patterns

Nutrient adequacy

Requirements

Micronutrient intake

Abbreviations

AI  

adequate intake

ANR  

average nutrient requirement

EAR  

estimated average requirement

INL  

individual nutrient level

IOM  

Institute of Medicine

KIDMED  

Mediterranean diet score in children

MDP  

Mediterranean dietary pattern

MUFA  

monounsaturated fatty acids

NAR  

nutrient adequacy ratio

NIVs  

nutrient intake values

SFA  

saturated fatty acids

UNL  

upper nutrient level

WDP  

Western dietary pattern

Introduction

In recent years there has been an increased interest in finding a dietary pattern that fulfills the nutritional requirements of a population. Assessing the quality of a diet to establish nutritional recommendations for individuals or populations is a priority [1]. Nutrient requirements are traditionally based on the minimum amount of a nutrient needed by an individual to avoid deficiency and are defined by the physiological needs of the body. Alternatively, the requirement can be defined as the intake at which health is optimal, including the prevention of chronic diet-related diseases [2].

The Mediterranean diet is recognized as a healthy dietary pattern [3]. It is characterized by a beneficial fatty acid profile with large amounts of monounsaturated fatty acids (MUFAs) and a higher MUFA-to-saturated fatty acid (SFA) ratio than Western-type dietary patterns [4,5]. In addition, consumption of a small amount of carbohydrates [5], combined with elevated intake of dietary fiber [6] and antioxidants [7,8], may work together to produce favorable effects on health status. Greater adherence to a Mediterranean diet has been related to a reduced risk of all causes of mortality, as well as lower incidence of or mortality from cardiovascular diseases, certain types of cancer, neurodegenerative diseases (Parkinson’s and Alzheimer’s disease), and type 2 diabetes [9,10].

Nutritional adequacy can be estimated by the comparison between the nutrient requirement and a certain individual’s or population’s intake. Because neither the real intake nor the real requirement for one individual is known, the assessment of the adequacy of an individual’s or population’s nutrient intake can be calculated as the probability of adequacy [1,11].

Nutritional Adequacy and Public Health

Rapid changes in diets and lifestyles resulting from industrialization, urbanization, economic development, and market globalization are having a significant effect on the health and nutritional status of populations [12]. Countries such as Spain and Italy have demonstrated a downward trend in adherence to the Mediterranean dietary pattern in recent decades [13,14].

The Mediterranean diet by the consumption of virgin olive oil, fruits, vegetables, whole-meal cereals, and fish, used to be rich in vitamins and minerals, making the risk of deficient micronutrient intakes quite infrequent. This could explain why inadequate intake of the vitamins such as B1, B2, niacin, B6, folates, or B12 were rare and intake of antioxidant vitamins (vitamins E and C) and carotenes were high in the Mediterranean basin [15,16]. The changes in the traditional Mediterranean diet in recent decades, however, include the incorporation of low nutrient-dense foods (such as soft drinks, sweets, bakery products) and variations in food processing methods (for example the refinement of flour). This transition has contributed to an increased risk of deficient intakes of some vitamins, especially folates and vitamins A and D, in particular among certain vulnerable population groups or collectives [15,16].

In 2011, Román-Viñas et al. [17] estimated the prevalence of inadequate nutrient intake in Europe using nutrient intake published data. The analysis of a number of micronutrients among adult and elderly European populations showed a mean prevalence of inadequate intake for zinc, iron, and vitamin B12 among 11% or less of the elderly population and a prevalence between 11% and 20% for inadequate copper intake in the adult and elderly populations, inadequate vitamin B12 in the adult population, and inadequate vitamin C in elderly Europeans. Finally, vitamin D, folic acid, calcium, selenium, and iodine were micronutrients with a prevalence of inadequacy in more than 21% of the adults and elderly; vitamin C had this prevalence of inadequacy only in the adult population [17]. Therefore surveillance of nutrient adequacy in Europe is needed to identify population groups at nutritional risk [11].

Nutritional adequacy can be used to determine the risk of deficiency of a nutrient in terms of low intake or high intake; for example, the adverse effects of high levels of sodium intake may be applicable to reducing the risk of certain chronic diseases or conditions such as hypertension [11,18]. The complexity of the relationships between dietary intake and pathology, however, cannot be attributed to a single nutrient but rather to multiple nutrients and foods. Thus the correct exposure should be measured to understand such a relationship. Furthermore, not only nutrients but also foods—and the interaction between them—are of concern for this kind of evaluation. Food pattern analysis is a key issue when investigating the relationship between nutrition and disease [11,19].

Methods of Assessing Nutritional Adequacy

The quality of a diet can be assessed in terms of nutrient intake and the level of compliance with nutrient requirements or in terms of food or food group intake and diet patterns [20,21]. Traditionally, as a consequence of the necessity of meeting the body’s needs for certain nutrients and avoiding deficiencies, nutrient intake assessment in populations has compared intake against the requirement for the nutrient. Different types of analyses are used to evaluate the nutrient adequacy of a diet. The method used depends on the purpose of the analysis (to evaluate individuals or a population), the nutrient being studied, and the type of distribution of the intakes [21]. Obviously, the recommendations used for the comparison are country specific and evidence based [11].

Recommended nutrient intake values (NIVs) vary between countries in the amount of nutrients and the terms used to describe the requirement [22]. Using the NIVs as a common set of terms and definitions, as a standardized terminology has been proposed by a group of experts from United Nations University (UNU), in collaboration with the Food and Agriculture Organization (FAO), the World Health Organization (WHO), and the United Nations Children’s Fund (UNICEF). The NIVs include three terms: the average nutrient requirement (ANR), the individual nutrient level (INLx), and the upper nutrient level (UNL) (Figure 1) [23].

Figure 1 Nutrient intake values and the risk of nutrient inadequacy or excess, showing the average nutrient requirement (1), the individual nutrient level (2), and the upper nutrient level (3). Adapted from the Institute of Medicine [18].

The ANR is defined as the average or median usual intake value that is estimated to meet the requirement for a specific criterion in a group at a certain life stage or of a particular sex. The ANR is equivalent to the estimated average requirement (EAR) used by the Institute of Medicine (IOM). The INLx is the recommended nutrient level for all healthy individuals in a specific subpopulation. The committees frequently add two standard deviations to the ANR, which covers the needs of most of the population (i.e., 98%), assuming that the distribution is symmetrical. The INL98 is equivalent to the recommended dietary allowance used by the IOM. Most nutrients have an UNL that is the highest daily intake that can be tolerated without risk of adverse health effects [11,23,24]. The term used by the IOM is tolerable upper intake level. Finally, an adequate intake (AI) is estimated if there is not enough scientific evidence to establish values for an ANR or INLx. The AI has been included in IOM recommendations but not in the standardized terminology proposed by the UNU [11,24]. These nutritional requirements are applied to both the nutritional assessment and the planning of dietary interventions on an individual and population-based level [1].

Although the first dietary recommended intakes were published in 1940 [25], little or no guidance on how to use them was given until the IOM published guidelines in 2000 describing how requirements where derived and their application. Even with these guidelines, not all researchers follow such advice; they apply the nutritional requirements in different ways to assess nutritional intake adequacy [1,11]. According to the IOM, the prevalence of inadequate intakes for groups can be estimated using two methods: the probability approach and the EAR (ANR) cut-point method [11,26].

The probability approach requires estimating the probability of inadequate intakes for each individual in a population subgroup, averaging the probabilities, and then using this average as an estimate of the prevalence of inadequacy [21]. The EAR cut-point method measures the prevalence of inadequate intakes as the proportion of the population with usual intakes below the ANR (or EAR). However, the EAR cut-point method requires the following conditions to be fulfilled: intakes and requirements for the nutrient being studied must be independent, nutrient requirements must be distributed symmetrically, and the variance of the distribution of requirements should be smaller than the variance of the usual intake distribution [27].

However, the relationship between dietary intake and disease is complex and cannot be reduced to the study of the effect that certain nutrients have on health. Not only nutrients but also foods and the interactions between them are of concern for such an evaluation. The first methods used to assess nutritional adequacy was the association between a combination of nutrients or foods and health [19]. The nutrient adequacy ratio (NAR) is an index of adequacy that compares an individual’s daily intake of a nutrient with the INL98 for that nutrient [28]. Mean adequacy ratio calculates the average for the NARs for the selected nutrients for a certain subject [28].

Diet indexes are known as a priori defined because they are based on previous knowledge of nutrition (dietary guidelines or recommendations). The so-called a posteriori approach consists of defining food patterns once the dietary data are collected and using statistical analyses to identify the current relevant food patterns within the study population [11,19]. The main statistical procedures used to analyze dietary data and identify dietary patterns are known as factor analysis or cluster analysis [29]. Both a priori hypothesis-oriented diet indices and a posteriori-defined patterns have been related to the incidence of health outcomes (hard clinical end points) and biomarkers in epidemiological or clinical studies. Some of these dietary patterns have been related to nutrient adequacy [11]. This approach parallels a validation study based on the rationale that if the classification of participants according to their adherence to the dietary pattern is able to determine whether they fail to reach the optimal nutrient intake, the use of the dietary pattern is sufficiently valid [19]. Some a priori-defined diet indices have been correlated with the adequacy of certain nutrients, for example, the revised Diet Quality Index [30], Healthy Eating Index [31], Dietary Diversity Score [32], and the Food Variety Score [33].

Similarly, the Mediterranean diet has been quantified in several diet indices established a priori as an attempt to globally evaluate the quality of the diet based on a traditional Mediterranean reference pattern [34]. For example, the Mediterranean Adequacy Index (MAI) is obtained by dividing the sum of the percentage of total energy from typical Mediterranean food groups by the sum of the percentage of total energy from atypical Mediterranean food groups. It was developed to assess how close a diet is to the Healthy Reference National Mediterranean Diet. Alberti et al. [35] found that MAI values of diets consumed by elderly participants from 10 European countries followed for 10 years were inversely associated with total mortality (HR: 0.83; 95% CI: 0.75–0.92). Serra-Majem et al. [36] developed the KIDMED (Mediterranean diet score in children) index to assess the adequacy of Mediterranean dietary patterns (MDPs) in children and young people; the results are discussed later in the section Mediterranean Diet in Children and Nutritional Adequacy.

Referring to the a posteriori-defined analysis, the studies evaluating the adequacy of nutrient intake associated with dietary patterns showed that the prudent pattern (defined by factor analysis as a diet rich in vegetables, fruits, legumes, whole grains, and fish) was valid for assessing the intake adequacy of α-carotene, lycopene, and lutein for men [37] and β-carotene, vitamin C, vitamin B6, and folic acid for women [38]. Despite the method used to identify dietary patterns, vitamin B12 and vitamin E were found to be the micronutrients with lower probabilities of being effectively assessed. Nevertheless, scientific evidence shows that diet indices are tools with fair to moderate validity for assessing micronutrient intake adequacy [11,19].

Mediterranean Diet, Western Diet, and Nutritional Adequacy

The MDP and the Western dietary pattern (WDP) differ not only in terms of food intake characteristics but also when nutrient adequacy is the comparative point. The relationship between nutrient adequacy and these two dietary patterns was recently assessed in a Mediterranean country by the Seguimiento de la Universidad de Navarra cohort study. In this study, the probability of adequate intake of nutrients was estimated using a probability approach and NIVs [5].

In Table 1 are shown the correlation coefficients between food consumption and factors representing both patterns. The WDP was positively correlated with the intake of red and processed meat, eggs, sauces, precooked food, fast food, energy drinks, sweets, full-fat dairy products, and potatoes and negatively correlated with the consumption of low-fat dairy products. Higher adherence to the WDP showed the highest percentages of individuals with noncompliance to recommendations for iodine, vitamin E, magnesium, iron, vitamin A, selenium, vitamin C, and folic acid. Furthermore, when adherence to the WDP was higher, the number of unmet nutrient intakes increased (Figure 2). Subjects in the highest quintile of the WDP had a 2.5-fold increased risk for ≥ 10 unmet NIVs when compared to the WDP group with the lowest adherence [15].

Table 1

Correlation Between Baseline Food Consumption and Factors Representing Mediterranean and Western Dietary Patterns in the Seguimiento de la Universidad de Navarra Cohort Study (n = 17,197)

Adapted from Serra-Majem et al. [5]

a Values are presented in grams per day.

b Correlation coefficients < 0.3 were omitted for simplicity.

Figure 2 Mean number of nutrients with intakes not meeting recommended levels across quintiles of Western dietary pattern score. Adapted from Serra-Majem et al. [5].

The food groups identified in the MDP were olive oil, poultry, fish, low-fat dairy products, legumes, fruits, and vegetables [5]. Higher adherence to the MDP was associated with a lower percentage of energy coming from total fat and SFA. The ratio of MUFA to SFA increased with increased adherence to the MDP (P for trend < 0.001). Protein intake (as a percentage of energy) increased across categories of adherence to the MDP. Carbohydrate intake was low (43–44%), showing a similar value across all the quintiles; on the other hand, consumption of dietary fiber increased according to the levels of adherence to the MDP. All the nutrients studied (except sodium) showed increasing values with increasing quintiles of adherence to the MDP. Therefore, subjects with a higher score for the MDP had a better nutrient profile, and a lower proportion of individuals showed inadequate intakes of micronutrients (Figure 3). Subjects in the highest quintile of the MDP had a lower risk of failing to meet ≥ 10 NIVs [OR: 0.02 (95% CI: 0.00–0.16, P for trend < 0.001] when compared to the lowest category of adherence to MDP [5].

Figure 3 Mean number of nutrients with intakes not meeting recommended levels across quintiles of Mediterranean dietary pattern score. Adapted from Serra-Majem et al. [5].

The MDP had similarities with the healthiest patterns (prudent [37,39], healthy [38], and health-conscious [40] patterns) defined in non-Mediterranean countries: a positive correlation with intakes of fruits, green leafy vegetables, poultry, and fish and certain lifestyle habits such as not smoking and being more physically active [41]. When the association of the dietary patterns with their nutrient intake profiles was analyzed, however, differences arose, especially in relation to fat intake. The prudent and healthy patterns had lower intakes of total and saturated fat [37,42,43], and some studies found even lower intakes of MUFAs [42,43]. Healthy patterns showed higher percentages of energy coming from proteins and carbohydrates and lower percentages of energy coming from fat [38,44] when comparing the highest quintile with the lowest.

In 2011, Maillot et al. [45] conducted a study that applied individual diet modeling in a representative sample of French adults to evaluate the smallest dietary changes needed to fulfill a whole set of nutrient recommendations for each individual. They found that including foods typically found in the Mediterranean diet was strictly necessary to achieve French nutrient recommendations. Therefore, MDP was directly associated with the MUFA-to-SFA ratio, showing a healthier profile for the quality of fat intake when compared to other studies conducted in non-Mediterranean countries. Furthermore, as adherence to the Mediterranean diet increases, the probability of nonfulfillment of nutrient recommendations decreases [5].

Mediterranean Diet in Children and Nutritional Adequacy

The Mediterranean dietary pattern has also been associated with nutritional adequacy in children. The enKid study was a cross-sectional study conducted in Spain that assessed 3166 individuals aged from 6 to 24 years [46]. A short questionnaire was used to evaluate the quality of the Mediterranean diet (KIDMED Index) (Table 2). This tool allowed us to classify the food intake of subjects into three categories of the Mediterranean diet quality (poor, medium, or high) [47]. The nutrient intake adequacy was estimated as the percentage of population with intakes less than two-thirds of the recommended nutrient intakes (<2/3 INL).

Table 2

KIDMED Test to Assess Adherence to the Mediterranean Diet

Adapted from Serra-Majem et al. [36].

Serra-Majem et al. found in the enKid study that total energy intake tend to increase according to the KIDMED Index in male adolescents aged 15 to 24 years. In children and adolescents the consumption of fiber, calcium, iron, magnesium, potassium, phosphorus, and vitamins, with the exception of vitamin E, increased according to the KIDMED Index. The proportion of children with inadequate intake of calcium, iron, and vitamins A and C (in girls), magnesium, and vitamin B6 (excluding boys aged 6–14 years), and decreased when the quality of the Mediterranean diet increased (Table 3) [36].

Table 3

Percentage of Inadequate Intakes (<2/3 INL) in School Children According to Adherence to the Mediterranean Diet

Adapted from Serra-Majem et al. [36].

The high nutritional quality of the Mediterranean diet contributes to the health benefits that have been ascribed to this dietary model. For this reason, in addition to better dietary fat quality and the increased quantity of antioxidants [7,48,49], we may consider nutritional adequacy as another favorable component of the Mediterranean diet. The enKid study demonstrated that when the level of adhesion to a Mediterranean diet model is optimal, there is a reduced risk of inadequate intakes, thus making fortification and supplementation of almost all vitamins and minerals unnecessary. Therefore, health promotion strategies should be prioritized to promote the Mediterranean diet instead of alternatives such as fortification or supplementation [27,50].

Summary Points

• In recent decades changes in the adherence to the MDP have contributed to the risk of inadequate intake of nutrients in the population.

• Nutritional adequacy should be assessed by comparing usual nutrient intake estimates with recommendations. However, dietary patterns may also be used because they correlate quite well with nutritional adequate intakes.

• The Mediterranean diet has similarities with other healthy dietary patterns; however, individuals with higher adherence to an MDP show a healthier profile of fat intake.

• When adherence to an MDP is high, the probability of fulfilling the nutrient recommendations increases.

• Health promotion strategies should prioritize the promotion of the Mediterranean diet instead of alternatives such as fortification or supplementation.

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