The nutrition transition

Improvement in food production has led to food abundance and poverty reduction over the past few decades. The result is a decrease of malnourished people in many developing regions in the world⁽ Reference Schmidhuber and Shetty ^{3 )}. However, despite the progress made, a significant number of people are still suffering from hunger and malnutrition with related health consequences. This is seen in the countries where the poor population has increased since 2008 because of the financial and economic crisis^{( 4 –} Reference Lang ^{6 )}. Indeed, besides the problem of insufficient protein and energy intake, there are many micronutrients deficiencies such as iron, iodine and vitamin A in millions of people in poor and middle-income countries including Africa.

The nutrition transition (NT) that is ongoing in these regions over the past two decades is one facet of a more general demographic, nutritional and epidemiological transition that accompanies development and urbanisation.

Passing from a rural to an urban lifestyle is marked by changes in dietary habits and physical activity patterns. These changes have led to a rapid increase in the prevalence of an emerging problem of malnutrition: overweight and obesity⁽ Reference De-Onis and Blössner ^{7 )} related to unhealthy diets and lifestyles among the poor people in these countries⁽ Reference Popkin ^{8 ,} Reference Gaziano ^{9 )}, associated with a high prevalence of CVD risks. With these changes induced by the accompanied epidemiological transition there is a shift from nutrient deficiency and infectious diseases characterising poor populations to the problems of chronic diseases namely obesity, diabetes, hypertension, stroke, hyperlipidaemia, CHD and cancer. These types of health problems were in the past characteristic of rich societies. The nutritional situation in the countries in transition generates profiles with different stages of declining undernutrition and increasing overnutrition or the coexistence of both under- and overnutrition even in the same household⁽ Reference Osman ^{10 )}.

Demographic transition

Despite the decline in population growth, population development is in continuous increase. It is predicted to grow by 2050 in countries where NT was reported such as the Middle East and North Africa, Africa, Asia and Latin America.

This population development is also combined, because of the progress in health, with a significant decrease in child mortality and a relatively slow onset of fertility and increasing life expectancy⁽ Reference Ragui and Farzaneh ^{11 – 13 )}. The existing level of malnutrition and the increasing population in many countries of Africa, the Middle East and Asia will have a major impact on the strategies required to meet the future global food and nutrient needs⁽ Reference Karoui ^{14 )}. Other challenges that will require increasing attention are geriatric nutritional problems due to the increase of expectancy and non-communicable diseases.

Another aspect of the transition is urbanisation that is growing rapidly in almost all developing countries^{( 15 )}. In all countries in Africa and Middle East and North Africa regions for instance, urban population is more than 50 %. In Morocco, it already achieved more than 55 % in 2004 and it is predicted to rise^{( 16 , 17 )}.

Epidemiological transition

In developing countries with different incomes, there is evidence of a triple burden of malnutrition, with the improvement of economic conditions. In these countries, while they are still struggling with undernutrition and infections, emerging problems of overnutrition such as obesity and diet-related non-communicable diseases are increasing. Since in most of these countries there is no available operational programme to address nutrition-related chronic diseases as the existing programmes are focused on the reduction of undernutrition, the consequences are to be of significant health and economic impact in the future. Non-communicable diseases, when combined with certain risk factors such as smoking, lack of physical activity, hypertension, hypercholesterolaemia, glucose intolerance, diet and obesity, lead to the onset of CVD and cancer. All these diseases which were characteristic of westernised societies in the past, are now emerging as a major health problem in developing and middle-income countries. One of the leading risk factors for these diseases is obesity caused by the NT. The increase of obesity prevalence has been well documented in the developed countries; however, with NT it is also increasing in developing countries including countries in Africa and Mediterranean area where a rapid change in the patterns of diseases is evident and now accepted by WHO and national governments. Besides, CVD metabolic syndromes are also emerging as a major health concern in these countries⁽ Reference Getz and Reardon ^{18 )}. This syndrome was also characteristic of Western societies in the past and its high prevalence has been documented in developed countries. The majority of metabolic syndrome components are also reported to be related independently to lifestyle factors namely diet, weight control and physical activity that are also accompanying NT⁽ Reference Rguibi and Belahsen ^{19 )}.

As consequences of NT, the food and nutrition situation show that despite efforts made in many regions, populations are still facing malnutrition and hunger. Indeed between 2000 and 2005, there is an increased number of undernourished and underweight children, concentrated in Africa and Asia^{( 20 , 21 )}. Also, moderate and severe forms of stunting and underweight are still highly prevalent especially in South Asia^{( 22 ,} Reference Khor ^{23 )}. Meanwhile, in addition to protein–energy malnutrition, more than 2 billion people in the world are affected by micronutrient malnutrition particularly iron, iodine, vitamin A and zinc deficiencies^{( 24 )}. In Sub-Saharan Africa and in Asia iron deficiency anaemia affects more than half of the children and women populations and in North Africa only, about 33 million people are suffering from iodine deficiency⁽ Reference Azizi and Mehran ^{25 )}. Another problem is vitamin A deficiency that affects more than 40 % in the developing world^{( 26 )}, with a prevalence and severity highly concentrated in South and Southeast Asia and Africa^{( 27 )}.

At the same time, the problem of overnutrition is emerging in low- and middle-income countries affecting all age categories and adding another burden of malnutrition beside that of undernutrition. Indeed, more than 500 million adults have obesity affecting more women than men and 43 million preschool children are overweight with high rate in North Africa⁽ Reference De-Onis and Blössner ^{7 )}. The continuous increase of obesity is associated with health consequences leading to high prevalence of CVD risks such as hypertension, diabetes, dyslipidaemia and metabolic syndrome and affecting even Mediterranean countries⁽ Reference Rguibi and Belahsen ^{19 , 24 ,} Reference Belfki, Ben Ali and Aounallah-Skhiri ^{28 – 31 )}.

Several factors associated with the ongoing transition, explain this widespread obesity namely accelerated processes of urbanisation, unhealthy lifestyle leading to physical inactivity or sedentary and dietary habit changes. In North Africa for instance, the prevalence of physical inactivity was estimated as 32 % of the population of those aged 40–69 years in Tunisia, 26 % of the population of those aged 25–64 years in Algeria and, 52 % of the population aged 20 years and older in Egypt^{( 31 )}. Sedentarity was reported to be associated with higher prevalence of obesity in women⁽ Reference Rguibi and Belahsen ^{19 )}. Another factor of obesity is the increase of food availability and food energy supplies that lead to a food energy consumption greater than the needs^{( 20 )}. The later factor is among the determining factors of obesity and CVD trends⁽ Reference Benjelloun ^{32 ,} Reference Rayner, Hawkes and Lang ^{33 )} and to CVD risks in North Africa and elsewhere⁽ Reference El ayachi, Mziwira and Vincent ^{34 )}.

Dietary transition in Mediterranean countries

Within the global transition there is also a change in diet in association with the changes accompanying the demographic transition. Indeed, regardless of the region diet is passing from a traditional to a westernised pattern. One example is in North Africa that belongs to Africa but also to the Mediterranean basin. The diet in this area is based on a large consumption of cereals and tubers, mainly wheat replacing barley, the traditional grains and consumption of fruit and vegetables. The consumption of animal products including fish remains very limited in this region. In urban households and high socioeconomic category in particular, food becomes more diversified and rich in micronutrients with the improvement of economic situation^{( 35 )}. However, in Morocco and Algeria, two countries of this region, the actual daily dietary fibre intake is lower and that of saturated fat is higher when compared to the traditional Mediterranean diet. Also, in Algeria <30 % of the subjects meet the recommendations for fat, carbohydrates and fibre.

In these countries, NT is also linked to a shift from a traditional Mediterranean dietary pattern that was marked by the use of traditional and local foods to a pattern characterised by food abundance, raised consumption, intense food production and economic interdependence. At the same time awareness to preserve the environment becomes a common problem for all stakeholders. However, in these countries the increase of obesity is linked to a high consumption of foods rich in sugar and fat. Indeed the trend of the consumption of the already prepared meals/foods and the number of restaurants is in continuous development^{( 36 , 37 )}.

The situation as described in the present paper raises the problem of sustainability of the traditional diet that is required for health sustainability. Rethinking and seeking a dietary model that reconciles nutritional requirements and also environment preservation is needed in this challenging situation. The Mediterranean dietary model, presented as a healthy and sustainable diet, could be an example of a diet to be promoted because it is nutritionally healthy, it is rich in biodiversity, it respects environment and it has beneficial role in the development of sustainable agriculture in the Mediterranean region.