3 ADOLESCENCE IS A PERIOD OF NUTRITIONAL VULNERABILITY Adolescence is also challenging for nutrition,even if nutritional vulnerability may not be as great as in infancy and childhood.Adolescents are exposed to undernutrition,micronutrient malnutrition as well as obesity.Their lifestyle and eating behaviours.along with underlying psychosocial factors. are particularly important threats to adequate nutrition. It may be said that adolescents are a nutritionally vulnerable group for a number of specific reasons, including their high requirements for growth,their eating patterns and lifestyles,their risk-taking behaviours and their susceptibility to environmental influences.Inadequate nutrition in adolescence can potentially retard growth and sexual maturation,although these are likely consequences of chronic malnutrition in early infancy and childhood.It can affect adolescents'current health and put them at high risk of chronic disease as well,particularly if combined with other adverse lifestyle patterns,even if the detrimental effects may take long to show.Compounded with growth,adolescent pregnancy exposes both mother and child to adverse health and socioeconomic consequences,particularly if the mother is stunted or undernourished.Hard physical work,as commonly observed in low-income countries,may impose additional physiological stress and nutritional requirements in adolescence.In certain cultures, from infancy onwards including adolescence,girls are at particularly high risk because of gender discrimination.In several countries of Asia,for instance,poorer nutritional status of women becomes apparent during adolescence,with a delay in maturation(Waslien and Stewart,1994). Even in countries like the USA and Canada,adolescents are considered as a nutritionally vulnerable subgroup because of their eating behaviours(Forthing 1991;Perry-Hunnicuft and Newman,1993). Adolescents,particularly girls,are increasingly conscious of their body and this has a bearing on their diet.Teenage girls may excessively restrict their energy intake out of a desire to be thin,which is an additional factor of health risk.In addition to this,adolescent girls as a group may be at risk for inadequate intake of iron and calcium (Health Canada 1999).Athletics may also increase physiologic stress in adolescents and therefore increase nutritional risk (Lifshitz,Tarim and Smith,1993). The principal nutrition problems facing adolescents and their consequences will be reviewed,followed by the main factors of nutritional risk.A conceptual framework illustrating the problems and their determinants is first proposed as an analytical model for the study of nutrition-related issues in adolescence worldwide. 3.1 Conceptual framework for the analysis of nutritional problems in adolescence The conceptual framework shown in Figure 1 illustrates the major nutritional issues in adolescence, whether nutritional problems as such or threats,along with underlying factors.This model,which is loosely adapted from UNICEF(1990),is deemed relevant for adolescents irrespective of geographic area or income level,although the magnitude of problems and priority issues may differ from one country to another,and even within countries.With the epidemiological and nutritional transition, coupled with globalization of economies,nutritional problems of industrialized countries become increasingly prevalent in low-and middle-income countries,notably obesity.Obesity,diabetes and hypertension are present in wealthy,middle-income and poor groups.It is recognized that the extremes of overnutrition and undernutrition are oftentimes concurrent problems in adolescent populations (Anderson 1991).Deficiencies can be found in poor societies because of poverty and in better-off groups NUTRITION IN ADOLES C E N C E /11
NUTRITION IN ADOLESCENCE /11 3 ADOLESCENCE IS A PERIOD OF NUTRITIONAL VULNERABILITY Adolescence is also challenging for nutrition, even if nutritional vulnerability may not be as great as in infancy and childhood. Adolescents are exposed to undernutrition, micronutrient malnutrition as well as obesity. Their lifestyle and eating behaviours, along with underlying psychosocial factors, are particularly important threats to adequate nutrition. It may be said that adolescents are a nutritionally vulnerable group for a number of specific reasons, including their high requirements for growth, their eating patterns and lifestyles, their risk-taking behaviours and their susceptibility to environmental influences. Inadequate nutrition in adolescence can potentially retard growth and sexual maturation, although these are likely consequences of chronic malnutrition in early infancy and childhood. It can affect adolescents’ current health and put them at high risk of chronic disease as well, particularly if combined with other adverse lifestyle patterns, even if the detrimental effects may take long to show. Compounded with growth, adolescent pregnancy exposes both mother and child to adverse health and socioeconomic consequences, particularly if the mother is stunted or undernourished. Hard physical work, as commonly observed in low-income countries, may impose additional physiological stress and nutritional requirements in adolescence. In certain cultures, from infancy onwards including adolescence, girls are at particularly high risk because of gender discrimination. In several countries of Asia, for instance, poorer nutritional status of women becomes apparent during adolescence, with a delay in maturation (Waslien and Stewart, 1994). Even in countries like the USA and Canada, adolescents are considered as a nutritionally vulnerable subgroup because of their eating behaviours (Forthing 1991; Perry-Hunnicuft and Newman, 1993). Adolescents, particularly girls, are increasingly conscious of their body and this has a bearing on their diet. Teenage girls may excessively restrict their energy intake out of a desire to be thin, which is an additional factor of health risk. In addition to this, adolescent girls as a group may be at risk for inadequate intake of iron and calcium (Health Canada 1999). Athletics may also increase physiologic stress in adolescents and therefore increase nutritional risk (Lifshitz, Tarim and Smith, 1993). The principal nutrition problems facing adolescents and their consequences will be reviewed, followed by the main factors of nutritional risk. A conceptual framework illustrating the problems and their determinants is first proposed as an analytical model for the study of nutrition-related issues in adolescence worldwide. 3.1 Conceptual framework for the analysis of nutritional problems in adolescence The conceptual framework shown in Figure 1 illustrates the major nutritional issues in adolescence, whether nutritional problems as such or threats, along with underlying factors. This model, which is loosely adapted from UNICEF (1990), is deemed relevant for adolescents irrespective of geographic area or income level, although the magnitude of problems and priority issues may differ from one country to another, and even within countries. With the epidemiological and nutritional transition, coupled with globalization of economies, nutritional problems of industrialized countries become increasingly prevalent in low- and middle-income countries, notably obesity. Obesity, diabetes and hypertension are present in wealthy, middle-income and poor groups. It is recognized that the extremes of overnutrition and undernutrition are oftentimes concurrent problems in adolescent populations (Anderson 1991). Deficiencies can be found in poor societies because of poverty and in better-off groups
Aiddns poo (Kuanod) eunn lepidKL 12/
12/ Malnutrition, micronutrient malnutrition, obesity, and other nutrition-related chronic diseases Malnutrition during fetal life/infancy/childhood; Low body stores Livelihood factors: -Sedentary lifestyle (or heavy physical work) - Alcohol - Smoking Typical eating styles of adolescents Cultural patterns & practices Changes in processed food supplies Lack of access to nutritious and safe food (poverty) Food supply deficit Eating disturbances Dietary inadequacies Early pregnancy Infectious diseases & other health problems Socioeconomic factors access to food; Food supplies Psychological factors Eating patterns Figure 1: A conceptual framework of nutritional problems and casual factors in adolescence
because of poor eating patterns.Undernutrition,specific micronutrient deficiencies,obesity and other markers of chronic disease are grouped as problems in the upper portion of the model.The same determinants are at play anywhere:dietary inadequacies as the primary underlying cause,frequently coupled with lifestyle factors and health conditions that further compromise nutritional status.Infection as a factor of malnutrition may be relatively less important in adolescents than in under-five children (although adolescents are highly exposed to HIV),while lifestyle factors become more critical.Early pregnancy is a major risk factor in adolescence anywhere.Past malnutrition,or low body nutrient stores, are in the background;they may have consequences during adolescence or further increase chronic disease risk later on in adulthood.Stunting,for instance,originates in foetal life,in infancy or in childhood. Determinants of dietary inadequacies are many,and they have been grouped under psycho-social and socioeconomic factors,while recognizing that they are intertwined.These factors are detailed in the Figure I and in the text as they are regarded as major threats to adequate nutrition in adolescence,along with lifestyles. Based on our review and other documents dealing with nutrition in adolescence(Gillespie 1997; Chungong 1998;Treffers 1998),the following are seen as the main nutritional issues of adolescents in low-and middle-income countries: undernutrition and associated deficiencies,often originating earlier in life; iron deficiency anaemia and other micronutrient deficiencies; obesity and associated cardiovascular disease risk markers; ·early pregnancy inadequate or unhealthy diets and lifestyles. While the first three are nutritional problems as such,the last two are risk factors that may result in nutritional problems.No ranking is attempted because while they are all critical,there are important variations in their relative magnitude,and hence in priority issues,depending on the population group considered. There are other nutrition-related problems that need not be overlooked,dental health problems for instance.There are also pathological conditions that alter nutritional status or require specific nutritional management,in particular diabetes and HIV/AIDS;these are discussed in Chapter 4 under'Case management of nutritional problems. 3.2 Nutritional problems in adolescence Adolescents'nutritional problems may represent a heavy health burden,but estimations of disability- adjusted life years lost (DALYS)made by the World Bank(1993)mainly take account of nutritional deficiencies among pre-schoolers and pregnant women.Furthermore,the deleterious effects of deficiencies in adolescents,and of nutrition-related disorders such as obesity,are ignored in these figures, in the short and in the long term (calcium,for instance,with osteoporosis),possibly owing to as yet insufficient data on their contribution to morbidity and mortality Up to recently,little was known about nutrition of adolescents,particularly in low-and middle-income countries.In 1990,the IRCW/USAID Nutrition of Adolescent Girls Research Program was established to provide information on factors that affect,and are affected by,nutritional status of adolescents (including boys),in order to guide the formulation of policies and programmes.Eleven widely different research projects were supported in Latin America and the Caribbean,in Asia and in Africa.Most studies were cross-sectional,but two were longitudinal and one was a food supplementation trial.These studies made a major contribution to the present knowledge of nutrition in adolescence(Kurz and Johnson- Welch,1994;Kurz 1996).Other than these,there is a dearth of data on adolescents'nutritional status in developing countries.This was underlined in the South-East Asia Region,and especially for non-school attending,non-pregnant adolescent girls aged 12 to 16 years,called the 'grey area'(WHO Regional Office for South-East Asia,1997).Not only data but also programmes to improve the health situation of NUTRITION IN ADOLES C E N C E /13
NUTRITION IN ADOLESCENCE /13 because of poor eating patterns. Undernutrition, specific micronutrient deficiencies, obesity and other markers of chronic disease are grouped as problems in the upper portion of the model. The same determinants are at play anywhere: dietary inadequacies as the primary underlying cause, frequently coupled with lifestyle factors and health conditions that further compromise nutritional status. Infection as a factor of malnutrition may be relatively less important in adolescents than in under-five children (although adolescents are highly exposed to HIV), while lifestyle factors become more critical. Early pregnancy is a major risk factor in adolescence anywhere. Past malnutrition, or low body nutrient stores, are in the background; they may have consequences during adolescence or further increase chronic disease risk later on in adulthood. Stunting, for instance, originates in foetal life, in infancy or in childhood. Determinants of dietary inadequacies are many, and they have been grouped under psycho-social and socioeconomic factors, while recognizing that they are intertwined. These factors are detailed in the Figure 1 and in the text as they are regarded as major threats to adequate nutrition in adolescence, along with lifestyles. Based on our review and other documents dealing with nutrition in adolescence (Gillespie 1997; Chungong 1998; Treffers 1998), the following are seen as the main nutritional issues of adolescents in low- and middle-income countries: • undernutrition and associated deficiencies, often originating earlier in life; • iron deficiency anaemia and other micronutrient deficiencies; • obesity and associated cardiovascular disease risk markers; • early pregnancy; • inadequate or unhealthy diets and lifestyles. While the first three are nutritional problems as such, the last two are risk factors that may result in nutritional problems. No ranking is attempted because while they are all critical, there are important variations in their relative magnitude, and hence in priority issues, depending on the population group considered. There are other nutrition-related problems that need not be overlooked, dental health problems for instance. There are also pathological conditions that alter nutritional status or require specific nutritional management, in particular diabetes and HIV/AIDS; these are discussed in Chapter 4 under ‘Case management of nutritional problems’. 3.2 Nutritional problems in adolescence Adolescents’ nutritional problems may represent a heavy health burden, but estimations of disabilityadjusted life years lost (DALYS) made by the World Bank (1993) mainly take account of nutritional deficiencies among pre-schoolers and pregnant women. Furthermore, the deleterious effects of deficiencies in adolescents, and of nutrition-related disorders such as obesity, are ignored in these figures, in the short and in the long term (calcium, for instance, with osteoporosis), possibly owing to as yet insufficient data on their contribution to morbidity and mortality. Up to recently, little was known about nutrition of adolescents, particularly in low- and middle-income countries. In 1990, the IRCW/USAID Nutrition of Adolescent Girls Research Program was established to provide information on factors that affect, and are affected by, nutritional status of adolescents (including boys), in order to guide the formulation of policies and programmes. Eleven widely different research projects were supported in Latin America and the Caribbean, in Asia and in Africa. Most studies were cross-sectional, but two were longitudinal and one was a food supplementation trial. These studies made a major contribution to the present knowledge of nutrition in adolescence (Kurz and JohnsonWelch, 1994; Kurz 1996). Other than these, there is a dearth of data on adolescents’ nutritional status in developing countries. This was underlined in the South-East Asia Region, and especially for non-school attending, non-pregnant adolescent girls aged 12 to 16 years, called the ‘grey area’ (WHO Regional Office for South-East Asia, 1997). Not only data but also programmes to improve the health situation of
adolescent girls and women in the region were deemed unsatisfactory.Appendix I provides a summary of existing data on malnutrition,micronutrient malnutrition and obesity in adolescents of developing countries. The overall nutritional status is better assessed with anthropometry,in adolescence as well as at other stages of the life cycle.Anthropometry is the single most inexpensive,non-invasive and universally applicable method of assessing body composition,size and proportions(de Onis and Habicht,1997). However,because of important changes in body composition during adolescence,and particularly during the puberty-related growth spurt which varies in its timing,assessment of obesity,or undernutrition,is more complex in adolescents than in adults or younger children.Much less is known and done on adolescent anthropometry than in younger age groups.It is possible that rapid changes in somatic growth in adolescence,problems of dealing with variations in maturation rate,and the difficulties involved in separating normal variations from those associated with health risk have been deterrents to developing a corpus of scientific knowledge linking adolescent anthropometry with determinants and outcomes. Nutritional status assessment in adolescence is an issue and it is further discussed under strategies and approaches in Chapter 4(section 4.5)because of the practical implications. 3.2.1 Undernutrition,stunting and consequences in adolescence 3.2.1.1 Overview on malnutrition in adolescence Overall nutrition status was shown to be very poor among adolescent girls of poor rural groups in India (Rajasthan).Chaturvedi et al(1996)reported that 79%suffered severe chronic energy deficiency(BMI <16),74%from anaemia and 44%had signs of vitamin B complex deficiency.On the basis of national recommended dietary allowances,intakes were grossly inadequate both in terms of energy and protein. Similarly,in urban Bangladesh,Ahmed et al(1998)reported inadequate intakes in a high proportion of schoolgirls aged 10-16 years,although these girls may be considered more privileged than their non- school counterparts,whether urban or rural.Only 9%met the recommended daily allowance (RDA) for energy and 17%for protein.Girls from less educated families (particularly mothers)were more likely to be thin and short for their age and to have diets of poorer nutritional quality. Based on available information,a general profile of adolescent girls'nutritional status was sketched in the South-East Asia Region(WHO Regional Office for South-East Asia,1997): "They are undernourished,indicating a chronic energy deficiency.Most often,the BMI of adolescent girls of 13 and above is below 18.5.The girls are usually physically stunted,a manifestation of chronic protein energy malnutrition and have a narrow pelvis indicating that the full growth of the pelvis has yet to take place.[Iron deficiency anaemia is the most glaring nutritional deficiency,[.with no less than 25-40%of adolescent girls as victims of moderate and sometimes severe anaemia.[..In all countries of the region,at least 40-50%of adolescent pregnant girls are anaemic" Undernutrition,defined as BMI <5th percentile of NCHS reference values(WHO 1995a),was highly prevalent in three of the 11 studies of ICRW:53%in India,36%in Nepal and 23%in Benin".Even where prevalence was high,BMI tended to improve with age.However,this may simply reflect a pattern of later maturation.In most studies allowing comparisons of boys and girls,there was twice as much undernutrition in boys as in girls.One possibility is a differential maturation in boys and girls;another one,which warrants further investigation,is connected with the high rates of anaemia,which could affect body weight of boys more than girls because the former put on more muscle than the latter(see Section 3.2.2). According to this empirical and statistical definition,the rate of 'undernutrition'in the reference population of American adolescents is accepted to be of the order of 5%
14/ 8 According to this empirical and statistical definition, the rate of ‘undernutrition’ in the reference population of American adolescents is accepted to be of the order of 5% adolescent girls and women in the region were deemed unsatisfactory. Appendix I provides a summary of existing data on malnutrition, micronutrient malnutrition and obesity in adolescents of developing countries. The overall nutritional status is better assessed with anthropometry, in adolescence as well as at other stages of the life cycle. Anthropometry is the single most inexpensive, non-invasive and universally applicable method of assessing body composition, size and proportions (de Onis and Habicht, 1997). However, because of important changes in body composition during adolescence, and particularly during the puberty-related growth spurt which varies in its timing, assessment of obesity, or undernutrition, is more complex in adolescents than in adults or younger children. Much less is known and done on adolescent anthropometry than in younger age groups. It is possible that rapid changes in somatic growth in adolescence, problems of dealing with variations in maturation rate, and the difficulties involved in separating normal variations from those associated with health risk have been deterrents to developing a corpus of scientific knowledge linking adolescent anthropometry with determinants and outcomes. Nutritional status assessment in adolescence is an issue and it is further discussed under strategies and approaches in Chapter 4 (section 4.5) because of the practical implications. 3.2.1 Undernutrition, stunting and consequences in adolescence 3.2.1.1 Overview on malnutrition in adolescence Overall nutrition status was shown to be very poor among adolescent girls of poor rural groups in India (Rajasthan). Chaturvedi et al (1996) reported that 79% suffered severe chronic energy deficiency (BMI <16), 74% from anaemia and 44% had signs of vitamin B complex deficiency. On the basis of national recommended dietary allowances, intakes were grossly inadequate both in terms of energy and protein. Similarly, in urban Bangladesh, Ahmed et al (1998) reported inadequate intakes in a high proportion of schoolgirls aged 10-16 years, although these girls may be considered more privileged than their nonschool counterparts, whether urban or rural. Only 9% met the recommended daily allowance (RDA) for energy and 17% for protein. Girls from less educated families (particularly mothers) were more likely to be thin and short for their age and to have diets of poorer nutritional quality. Based on available information, a general profile of adolescent girls’ nutritional status was sketched in the South-East Asia Region (WHO Regional Office for South-East Asia, 1997): “They are undernourished, indicating a chronic energy deficiency. Most often, the BMI of adolescent girls of 13 and above is below 18.5. The girls are usually physically stunted, a manifestation of chronic protein energy malnutrition and have a narrow pelvis indicating that the full growth of the pelvis has yet to take place.[...] Iron deficiency anaemia is the most glaring nutritional deficiency,[....] with no less than 25-40% of adolescent girls as victims of moderate and sometimes severe anaemia. [....] In all countries of the region, at least 40-50% of adolescent pregnant girls are anaemic”. Undernutrition, defined as BMI <5th percentile of NCHS reference values (WHO 1995a), was highly prevalent in three of the 11 studies of ICRW: 53% in India, 36% in Nepal and 23% in Benin8 . Even where prevalence was high, BMI tended to improve with age. However, this may simply reflect a pattern of later maturation. In most studies allowing comparisons of boys and girls, there was twice as much undernutrition in boys as in girls. One possibility is a differential maturation in boys and girls; another one, which warrants further investigation, is connected with the high rates of anaemia, which could affect body weight of boys more than girls because the former put on more muscle than the latter (see Section 3.2.2)
In Nigeria,a study among adolescent girls(Brabin et al,1997)showed that undernutrition was more widespread in rural than in urban areas:10%of rural and 5%of urban girls were stunted(E2d percentile, British reference values of 1990),and 16%vs 8%could be considered thin (E9t percentile BMI).However, there may be wide infra-urban variations according to socioeconomic status(SES),which is not known. It is not known either,in the absence of longitudinal data,to what extent early adolescent stunting might be compensated for in late adolescence.There was no important problem with overweight in rural or urban groups. In emergency situations,particularly when crisis situations persist for long periods of time,adolescents may be affected by severe undernutrition,much like younger children,although in many cases therapeutic nutrition programmes are not open to them.Using the 5th percentile of NCHS/WHO BMI reference values as an indicator of acute undernutrition,a report on Somali and Sudanese refugees in Kenya indicated that roughly 60%of 10-19 year-old people were undernourished.However,the authors themselves suggest that this cut-off may overestimate the real extent of severe malnutrition in this age group,based on ancillary data on morbidity and mortality rates.Severely undernourished adolescents may be at lower risk of death or opportunistic infection than pre-school age children,and yet data from refugee camps in Africa showed that 48%up to 73%of excess deaths were among people above 5 years of age(Davis 1996).Adolescent refugees'capacity to do physical work may be seriously curtailed by severe undernutrition,which further compromises their own and their family's welfare because of resulting limitations in food production and other income-generating physical activities.Preliminary results of a recent survey on a random sample of adolescent Nepali refugees from Bhutan (Woodruff et al,1999)show a lower rate of undernutrition than in Kenya,with 34%of adolescents having a BMI lower than the 5th centile of WHO reference population for sex and corrected age for delayed puberty. Angular stomatitis sugestive of riboflavin deficiency was observed in 29%of the adolescents,a deficiency which is now seldom observed in stable populations.Overall,26%were anaemic.Rates of low BMI were similar in adolescents and in adults.However,in the absence of comparable data from the Nepali population,and since the BMI cut-offs may not apply to all adolescent populations,it is not possible to conclude that undernutrition in these refugees represents a public health problem. Stunting is commonly observed among adolescents in undernourished populations.In the ICRW studies, stunting(height <5th percentile of NCHS/WHO reference data)was highly prevalent in nine of the 11 studies,ranging from 27%in urban Guatemala to 65%in rural Philippines(Kurz and Johnson-Welch, 1994).Short stature in adolescence is mainly caused by infection and inadequate dietary intake during the pre-school years,and foetal malnutrition may also be a factor.However,ethnic differences may be present and would have to be taken into account,more so in adolescence than earlier on'.In both African studies,males were worse off than girls,whereas the reverse was true in India.A possible explanation for the former was that in Africa,boys are encouraged to be autonomous at a younger age than girls,meaning that they are more likely to be exposed to infection.The gender difference in India was tentatively explained by the deeply embedded sociocultural and economic practices that often discriminate against females of all ages.It may also be that growth is delayed in adolescents,more so in boys than in girls,perhaps owing to transient anaemia(see Section 3.2.2). Longitudinal studies conducted in Guatemala provide strong evidence for the important role of early childhood nutrition on anthropometric nutritional status of adolescents.These studies indicate that in this population,most of the growth deficit observed in adolescents and adults occurred during the first three years of life.The positive effects of energy and protein supplementation during the first three years of life indeed persisted at adolescence:height,weight and fat-free mass were still higher in the supplemented than non-supplemented individuals(Kurz and Johnson-Welch,1994;Rivera et al,1998). Woodruff B,Bhatia R,NGONut Listserv Discussions,Feb.5,1999(ngonut@abdn.ac.uk) 10 For instance,the studies of Leung and Lui in Hong Kong,which provide evidence of a stable systematic difference in stature between northern and southern Chinese.In Hong Kong,the secular trends of growth in height have flattened,and it is questionable that high rates of 'stunting'as defined by reference to NCHS reference data should be interpreted as a residual effect of former nutritional compromise,in this generation or the previous oneion(S Oppenheimer,on Ngonut network,ngonut@abdn.ac.uk,22/04/99) NUTRITION IN ADOLES C E N C E /15
NUTRITION IN ADOLESCENCE /15 9 Woodruff B, Bhatia R, NGONut Listserv Discussions, Feb. 5, 1999 (ngonut@abdn.ac.uk) 10 For instance, the studies of Leung and Lui in Hong Kong, which provide evidence of a stable systematic difference in stature between northern and southern Chinese. In Hong Kong, the secular trends of growth in height have flattened, and it is questionable that high rates of ‘stunting’ as defined by reference to NCHS reference data should be interpreted as a residual effect of former nutritional compromise, in this generation or the previous oneion (S Oppenheimer, on Ngonut network, ngonut@abdn.ac.uk, 22/04/99) In Nigeria, a study among adolescent girls (Brabin et al, 1997) showed that undernutrition was more widespread in rural than in urban areas: 10% of rural and 5% of urban girls were stunted (£ 2nd percentile, British reference values of 1990), and 16% vs 8% could be considered thin (£ 9th percentile BMI). However, there may be wide infra-urban variations according to socioeconomic status (SES), which is not known. It is not known either, in the absence of longitudinal data, to what extent early adolescent stunting might be compensated for in late adolescence. There was no important problem with overweight in rural or urban groups. In emergency situations, particularly when crisis situations persist for long periods of time, adolescents may be affected by severe undernutrition, much like younger children, although in many cases therapeutic nutrition programmes are not open to them. Using the 5th percentile of NCHS/WHO BMI reference values as an indicator of acute undernutrition, a report on Somali and Sudanese refugees in Kenya indicated that roughly 60% of 10-19 year-old people were undernourished9 . However, the authors themselves suggest that this cut-off may overestimate the real extent of severe malnutrition in this age group, based on ancillary data on morbidity and mortality rates. Severely undernourished adolescents may be at lower risk of death or opportunistic infection than pre-school age children, and yet data from refugee camps in Africa showed that 48% up to 73% of excess deaths were among people above 5 years of age (Davis 1996). Adolescent refugees’ capacity to do physical work may be seriously curtailed by severe undernutrition, which further compromises their own and their family’s welfare because of resulting limitations in food production and other income-generating physical activities. Preliminary results of a recent survey on a random sample of adolescent Nepali refugees from Bhutan (Woodruff et al, 1999) show a lower rate of undernutrition than in Kenya, with 34% of adolescents having a BMI lower than the 5th centile of WHO reference population for sex and corrected age for delayed puberty. Angular stomatitis sugestive of riboflavin deficiency was observed in 29% of the adolescents, a deficiency which is now seldom observed in stable populations. Overall, 26% were anaemic. Rates of low BMI were similar in adolescents and in adults. However, in the absence of comparable data from the Nepali population, and since the BMI cut-offs may not apply to all adolescent populations, it is not possible to conclude that undernutrition in these refugees represents a public health problem. Stunting is commonly observed among adolescents in undernourished populations. In the ICRW studies, stunting (height <5th percentile of NCHS/WHO reference data) was highly prevalent in nine of the 11 studies, ranging from 27% in urban Guatemala to 65% in rural Philippines (Kurz and Johnson-Welch, 1994). Short stature in adolescence is mainly caused by infection and inadequate dietary intake during the pre-school years, and foetal malnutrition may also be a factor. However, ethnic differences may be present and would have to be taken into account, more so in adolescence than earlier on10 . In both African studies, males were worse off than girls, whereas the reverse was true in India. A possible explanation for the former was that in Africa, boys are encouraged to be autonomous at a younger age than girls, meaning that they are more likely to be exposed to infection. The gender difference in India was tentatively explained by the deeply embedded sociocultural and economic practices that often discriminate against females of all ages. It may also be that growth is delayed in adolescents, more so in boys than in girls, perhaps owing to transient anaemia (see Section 3.2.2). Longitudinal studies conducted in Guatemala provide strong evidence for the important role of early childhood nutrition on anthropometric nutritional status of adolescents. These studies indicate that in this population, most of the growth deficit observed in adolescents and adults occurred during the first three years of life. The positive effects of energy and protein supplementation during the first three years of life indeed persisted at adolescence: height, weight and fat-free mass were still higher in the supplemented than non-supplemented individuals (Kurz and Johnson-Welch, 1994; Rivera et al, 1998)