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close this bookFood and Nutrition Bulletin Volume 09, Number 4, 1987 (UNU Food and Nutrition Bulletin, 1987, 88 pages)
close this folderNutrition and urbanization
View the documentNutrition and urbanization: Introduction
View the documentHealth services and environmental factors in urban slums and shanty towns of the developing world
View the documentTrends in urban and rural food consumption and implications for food policies in Tunisia
View the documentNutrition-related health consequences of urbanization
View the documentUrbanization and hunger in the cities

Nutrition-related health consequences of urbanization

Fernando E. Viteri, M.D.

Introduction

This paper specifically describes and analyses nutrition-related health problems in urban populations, with emphasis on less-developed countries, anticipates future trends, and places the magnitude of the problems in the context of the total dimensions of the nutritional and health conditions in low-income countries.

The word "urban" may be used in reference to (1) an inhabited place administratively identified as a city and its dwellers, (2) a place with a concentrated population of a certain size living in relatively permanent locations (i.e., a city of a given number of inhabitants whether with a minimal population density or not, or (3) an ecosystem and its population (relatively independent of size) with some or all of the following characteristics: crowding, a cash economy, a low level of occupational physical activity, the predominance of manufacturing, bureaucratic, and service occupations, little contact with plants and animals and their cultivation, and some degree of organized public services. Closely linked to such an ecosystem is the word "urbanism," which refers to a way of life affected by "the consequences, both social and personal, of life in urban environments" [1] (see table 1).

The phenomenon of westernization is defined as the adoption of several characteristics of the Western developed world, particularly life-style and economic, dietary, and health-seeking behaviours. For clarity we must also distinguish modernization from westernization and urbanism. The term modernization is used here to imply the processes and consequences associated with cumulative socio-economic advances, including placing greater social value on women and on children (reducing the demand for children as contributors to the family's economy) [2, 3].

It is evident that these three processes often appear together as societies undergo urbanization, which actually refers to the increase in the proportion of a population living in urban settings. A proportion of urban dwellers may not accept the urban way of life (urbanism) or become westernized or modernized. On the other hand, population groups in non-urban settings may accept these ways of life more effectively. This is particularly true in agricultural areas undergoing industrialization (agro-industrial complexes) and in towns and villages around large cities, especially when, as is often the case in the developing world, one city has absolute primacy.

Dimensions of urban growth

According to a United Nations report [4], the rate of growth of urban populations is close to 4.0% a year in less-developed countries and 1.8% in developed countries. Over two billion persons in less-developed nations will be urban by the year 2000, while slightly over one billion inhabitants of developed nations will be urban. What is more significant in terms of the implications of urbanization for nutrition and health is the 7.7-fold increase of the urban population in underdeveloped countries in the last 50 years (in contrast to a 2.4-fold increase in the rural population) and the appalling fact that in these countries the proportion of households in poverty in urban settings is increasing explosively, so that by the year 2000, 57% of all poor households will be urban in contrast to 34% in 1980 (table 2).

The UN projections of an absolute decline in poor rural households in the last two decades of this century appear optimistic. This may very well be the result of the definition of "urban population," which reclassifies previous rural settings as urban due to rural pert-urban environments being incorporated into the expanding cities.

Also of importance in terms of the dimensions and characteristics of urbanization is the proportion of population growth attributable to the natural increase in the number of city dwellers and that due to inmigration, since the two processes impose different social, economic, health, and nutrition needs and demands on the urban population and on the city environment. The United Nations report [4] estimated that about half the urban growth in emerging countries is due to each of the processes. In Latin America, the proportion of growth due to migration averages 34%. These data are based on the latest information available for the 1980 UN report in a total of 28 countries.

Causes of migration into the urban setting

Several studies 16-101 indicate that people migrate to the cities primarily because of social and economic attraction plus the prestige associated with living in the city. Historically, urban compounds began to form as the agricultural revolution evolved; cities developed further as trading, religio-political, and strategic centres up to mid-eighteenth century, when very rapid urban expansion began in Europe with the industrial revolution and accelerated the demand for labour in production and trading centres.

Urban development in the less-developed countries followed different motives, paths, and rhythms primarily because of their historical, colonial, and neocolonial factors. The cities grew, but essentially as political and trading centres, giving marked primacy to only one or a few. Only lately has the rural environment been incorporated into the urban growth (beginning in the late nineteenth and early twentieth centuries), and industrial development has only more recently sprung up in developing nations. Rural-to-urban migration accelerated in part as a response to these developments, but in many cities immigration and urban growth occurred in the absence of a significant increase in the industrial job market, creating large urban subsistence, commercial, and service sectors. At the same time, substantial declines in mortality with persistent accelerated birth rates in both the urban and rural environments resulted in a rapid population growth. This has been associated with expansion of cash crops, fragmentation of small subsistence plots, and penetration of industrially manufactured goods into the rural areas, displacing less efficient small household and artisan industries and creating a large rural push to the city.

The process of urban growth in less-developed countries is evolving very differently from that in developed countries. Its stages lag about 75 years behind those of developed nations; urbanization is the product of different history and causes, and involves both much greater growth in absolute numbers and much higher rates of growth than in Europe in the late nineteenth century (there is debate on this last issue [9, 11, 12]). An important difference is that in Europe and the developed world in general, industrial growth came before urbanization. In the emerging nations it does not; moreover, even where industrial growth is occurring, it is generating only a very small number of jobs [13].

TABLE 1. Characteristics usually associated with urban in contrast to rural populations

Socio-economic and environmental characteristics    
Cash economy and high advertising pressure
High environmental contamination
Higher development of public services
(water. sewerage, electricity, telephones, etc.)
Diversity of occupational niches and greater specialization
Diversity in socio-economic levels
Diversity of foods available
Greater need of mobility and transportation systems
Greater availability and diversity of
health care and other social services
Greater educational, work, and recreational opportunities
Crowding
More stable micro-climates, particularly at work
Limited food production, if any
Biological characteristics    
Diversity in genetic endowment
Diversity in growth and development
Diversity in dietary intake, with higher energy density;
greater consumption
of purchased goods
Lower demands for physical activity
Lower energy expenditure
Behavioural characteristics    
Diversity in value and belief systems
Diversity in acceptable behaviour
Accelerated change (urbanism, moderniza- tion, westernization)
Higher level of social interaction and mobility
Greater demands on self-reliance and adaptation

Higher levels of aggressive beha
viour and social maladjustment

TABLE 2. Poor households in rural and urban areas in less developed countries, 1980 and projections for the year 2000

  1980 2000 Change (%)
Householdsa Urban as % of
total
Householdsa Urban as % of
total
Rural Urban Rural Urban Rural Urban
Eastern Africa 6,458 1,369 17 8,625 4,703 35 + 34 + 244
Western Africa 2,938 1,405 32 2,238 3,227 59 - 24 + 130
East Asia and the Pacific 12.553 4,155 25 9,872 5,744 37 - 21 + 38
Europe, Middle East, North Africa 3,761 6,250 62 1,403 8,743 86 -63 +40
Latin America and the Caribbean 4,932 14,023 74 1,621 19,328 92 - 67 + 38
South Asia 48,799 13,970 22 32,709 32,555 50 - 33 + 133
Total 79,441 41,172 34 56,468 74,300 57 - 29 + 80
Total rural and urban 120,613 130,768 + 8

a. In thousands.

Sources: Refs.4 and 5.

Effects of migration into the urban setting

In less-developed countries the short-term health and nutrition problems exhibited by the migrant poor in the shanty towns are, in large measure, those that were already affecting them as rural poor. These problems may even be exacerbated in the early months of city living by the possible higher degrees of infection and stress. A short-term variant of the well-known phenomenon of circular rural-urban-rural migration is also provoked by the marked concentration of secondary and tertiary levels of health care in the cities, which attract the rural sick in need of medical attention. The sick and those who accompany them move to the city and report themselves as urban dwellers in order to be eligible for free medical care. This has the effect, in terms of health statistics, of diminishing the true urban-rural differentials of ailments that are predominantly rural. In addition, it increases such differentials in the case of chronic "ailments of affluence" that predominantly affect urbanites.

Migration often results in a decline in subsistence agriculture (less technologically developed), which is often the responsibility of women, children, and the elderly. This affects the availability of food for the rural poor, particularly when there are high demographic pressures on land use and where marginal lands are the source of subsistence crops [14, 15]. Urban demands for services, intensified by rapid growth, draw national resources from rural development and deplete the rural sector further [16].

The environment

The diversity and the magnitude of differences of living conditions, demands, and opportunities in the cities are very important as determinants of nutrition and health. The negative effect of rapid and disorganized urban growth on services is well documented. Most poor, marginal areas in rapidly growing cities and other shanty towns lack adequate housing, water, and sewerage services, solid-waste disposal, prevention of environmental contamination, food sanitation control, personal security, and general safety systems (including accident prevention), electricity, communication systems (streets, transportation, mail, telephone), recreational facilities, accessible education and health services, and food outlets [171. This situation is obviously not conducive to physical and mental health. The deterioration that is rather typical of the large cities in less developed countries where economic as well as population growth has taken place without a workable plan, has been described as follows for Lagos:

Chaotic traffic conditions have become endemic; demands on the water supply system have begun to outstrip its maximum capacity; power cuts have become chronic as industrial and domestic requirements have both escalated; factories have been compelled to bore their own wells and to set up standby electric plants; public transport has been inundated, port facilities stretched to their limits; the congestion of houses and land uses has visibly worsened and living conditions have degenerated over extensive areas within and beyond the city's limits, in spite of slum clearance schemes; and city government has threatened to seize up amidst charges of corruption, mismanagement and financial incompetence. Moreover, although employment has multiplied in industry, commerce and public administration, there is no doubt that thousands of in-migrants have been unable to find work, and the potential for civil disturbances has increased [181.

Life in the city is not all bad, however, and according to several authors [1, 19-21 ] the city provides an environment in which individual and group expressions are feasible, where social mobility is a reality, and where conditions are in general better and more attractive than in the poor rural areas. It has been argued that some less-developed countries are over urbanized, but a clear counter-argument has been that such countries are in reality "over-ruralized" [1] and at the same time are fundamentally underdeveloped in the rural sector. The fact is that the poor rural environment appears worse than even the city slums; the constant urban in-migration from the non-urban sector proves it.

Food intake and nutrient adequacy

There is ample evidence that household food purchases and consumption vary by income levels in both developed and developing countries and in urban as well as in rural settings 122-27]. In developing nations, the level of food and nutrient intake, even of the lowest-income rural and urban groups, is enough to prevent widespread, severe deficiency diseases. Exceptions are iodine in some areas and iron in some specific age-sex groups. Mild and moderate deficiencies and temporary shortages of food are, nevertheless, not uncommon among these groups, as evidenced by the better nutritional conditions of low income populations who receive food aid or other social anti-poverty programmes compared to those who do not (e.g., women-infants-children programmes in the United States).

Moderate to severe nutrition deficiencies are common among the lower socio-economic strata in both urban and rural settings. The effect of location on the differential of food availability by income has not been studied properly, but in theory the urban poor are more vulnerable than the rural poor who are engaged in subsistence agriculture. Enough evidence exists, however, to indicate that the rural landless and those in rural areas undergoing modernization are particularly sensitive to economic shortages 128]. In populations involved in agricultural exploitation of marginally productive land, seasonal food scarcity is the rule. The urban poor are subjected to smaller seasonal fluctuations in food availability and intake 129].

By favouring modernization, the urban environment has been fertile ground for the promotion of bottle-feeding at the expense of maternal lactation, particularly among households where the demands of urbanism impose various limitations on adequate breast feeding 15]. On the other hand, weaning and complementary feedings are in general better accomplished among urban populations. In addition, the diets of young children and households in the cities tend to incorporate a greater variety of foods than those in the rural setting.

As the socio-economic level increases in the city, a better-quality diet is established, even though the total macronutrient intake may improve less [30]. These characteristics are significant for adequate child nutrition because of the critical importance of protein quality and energy and nutrient density to children.

When urban and rural diets are compared, it appears that variation in dietary intake depends more on the country and socio-economic group than on urban or rural location. In countries where urban diets are poor, rural diets are poor as well, and often worse. As the general socio-economic condition of a country improves with a factor of equity, the differentials in urban-rural intake (which more often favour the former) tend to disappear.

Even though many comparisons of urban-rural diets do not consider socio-economic rankings (weakening their significance), the intake of urban populations, even of the poor, tends to be better, or at least not significantly worse, than that of the rural poor. It is not rare that, as urbanization proceeds around established cities, dietary intake improves over that in isolated urban areas.

TABLE 3. Prevalence of diarrhoea, fever, and other illnesses (percentages of children) among preschool children in poor urban and rural populations in selected countries

  Number
of survey
sites

Site averages

Diarrhoea Fever Other illness
Mean Range Mean Range Mean Range
Bolivia (1981) [31]  
urban 3 17.7 11 -28 15.7 9-26 1 8.3 15-22
rural 3 14.7 8-24 15.7 8-24 16.3 14-22
Cameroon (1978) [32]  
urban 1 16 - 24 - 22  
rural 6 15.8 11-22 23.0 19-34 24.7 17-31
Egypt (1978) [33]  
urban 4 13.0 8-21 18.7 12-31 19.2 12-28
rural 3 9.8 9-11 16.3 15-17 15.1 13-18
Swaziland (1983) [34]  
urban 4 14.5 - - - - -
rural 16 16.4 11 -23 - - - -

Source Ref. 35

In adults, energy expenditure established by occupation and leisure activities must be taken into consideration in interpreting the possible nutritional consequences of dietary intake. Evidence indicates that urban occupations generally demand less energy than rural occupations. Thus lower energy intake among urban adult populations (and households) does not necessarily mean that these individuals are less well nourished than their rural counterparts. In many countries, the prevalence of obesity is actually higher among urban poor children and adults, suggesting that life-style plays a very significant role in the energy adequacy of diets in the city.

In summary, urban diets, including those consumed by the poor, are commonly more varied than rural diets. Also the poor, whether urban or rural, consume diets that are often deficient. Even though the urban setting may offer some advantage in terms of variety and stability of supply, the more important factor affecting food intake continues to be poverty.

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