To the best of our knowledge, this study is the first of its kind in generating the WHO-based growth charts [13
] for a nationally representative sample of children from the MENA region.
Comparison of the consistency of the growth charts of Iranian children aged 10–19
years with the international growth references revealed that the density of the tale distribution of boys/ girls BMI Z-scores are higher than that of WHO2007 (Figure ), resulting in the existence of under- and over-weight children. This is in agreement with the findings that 8% and 21% of participants had low and high BMI respectively. Moreover, the boy/girl height smoothed Z-scores were shifted toward the left (Figure ) indicating that there exist children whose height is below the normal range. This supports the findings that 7% were stunted.
Urbanization and nutritional transition as two important factors of epidemiological transition in Iran, similar to many other developing countries [31
], are responsible for the emerging growth disorders in terms of underweight, overweight and obesity. Consumption of fat rich in saturated and trans-fatty acids has become a very popular component of everyday life in Iran which has undergone a rapidly occurring nutritional transition. Over-nutrition (overweight and obesity) and under-nutrition (thinness, sever thinness and stunting) do exist simultaneously in different age groups and also genders (Table
and ).This could support that Iranian children aged 10–19
years are facing a double burden of growth disorders. This finding is consistent with our previous national report from Iran, as an upper-middle-income country [32
Overweight and obesity are serious public health problems in many countries. Overweight affects 30%–80% of adults in the European countries. About 20% of children and adolescents are overweight, and a third of these are obese [33
]. BMI is a widely used body weight classification system but has known restrictions, and may need to be adjusted for sitting height in order to be useful as an indicator of health risks in special populations. The BMI may overestimate the number of individuals that are overweight and obese, and hence at risk for type 2 diabetes mellitus and cardiovascular disease among the population [33
]. In our study, the prevalence of overweight was 14.5% (13% for boys and 16% for girls, respectively) and the corresponding figure for obesity was 6% (8% for boys and 4% for girls, respectively). This result is considerably higher than the prevalence rate of 4% reported for China [34
], but lower than 19.3% and over 20% found in Jamaica [35
] and the United States of America [36
], respectively. A study conducted in India [37
] showed that the prevalence of obesity in affluent adolescent schoolchildren was 7.4%, and higher in males than in females similar to that of other study in Germany [38
The maximum prevalence of obesity was found during the pubertal period ,i.e. between 10 to 12
years. This study showed that obesity was higher in boys than in girls. However, there are some documents that propose a higher prevalence of overweight and obesity in Iranian girls [39
]. Being overweight adolescents, particularly boys, are more likely to have high serum cholesterol and abnormal lipoproteins levels in adulthood [40
]. These consequences suggest an imbalance in the food intake of the population containing high energy foods especially carbohydrates and fats [41
In the current study, the height of Iranian boys aged 14
years and above fell below references ranges. However, as much as (7%), 52% of the boys and 48% of the girls had height-for-age z-score values lower than -2SD of the WHO 2007 reference data. This disproportion in the prevalence of stunting in genders is in agreement with some other studies [42
]. Some countries have high prevalence of stunting. For example rural Bangladesh has the highest prevalence of thinness and stunting (67% and 48% respectively) among adolescents. The 7% prevalence rate for adolescent was stunting as under- nutrition reported in this study is lower than the 18% reported for China [34
] or 42.2% , 36.00% and 53.00% reported for adolescents in a Pakistani public school, Nepal and India respectively [37
]. Twenty-five percent of the individual’s achieved height is attained during adolescence, which usually marks the end of growth [44
]. The inferences of nutritional disadvantage for boys are unclear. Some studies showed that this issue is related to the boys’ delayed and longer growth spurt [4
]. Stunting problem among girls has some important consequences in adulthood. A short woman tends to have a small pelvis and, therefore, is more likely to have hard delivery during childbirth [45
The same trend was noticed for thinness and severe thinness as more boys than girls had z-score BMI-for-age values below -2SD and -3SD, respectively. Thinness may also limit school achievement and work productivity. Adolescents also provide a good proportion of the productive work force in such environments. Therefore, there is an urgent need to develop strategies to improve the growth and nutritional status of adolescents.
The main limitation of this study is that the national survey was cross-sectional. Future longitudinal studies considering the cardio-metabolic risk factors and genetic examinations should be accomplished to better characterize the nature of the nutritional transition documented in the current study. Moreover, we could not examine the pubertal status of the study participants.
In the meanwhile, the BMI cut-off values used to detect malnutrition was based on the universal indices proposed by WHO reference 2007. Some studies e.g. [46
], showed that the malnutrition cut-offs are needed to be re-defined in some Asian countries [47
]. The conclusion by the WHO [48
] was that WHO BMI cut-off points should be retained as international classifications. However, there are some evidences that the ethnic differences must be taken into account. For example, global comparisons of the prevalence have showed Asians have ethnic predisposition to central body fat deposition and the metabolic syndrome even in a pediatric age [49
]. Findings of our previous national study revealed ethnic differences in the cardio-metabolic risk factors ; it showed considerably higher prevalence of dyslipidemia, in terms of low HDL-C and hypertriglyceridemia in Iranian children and adolescents compared with their German and Brazilian counterparts [49
]. These differences might be because of genetic-environment interactions. Future longitudinal studies considering biologic and biochemical risk factors can determine the impact of such ethnic differences in cardio-metabolic risk factors and the existing differences on the growth pattern of children in various populations on the incidence of CNCDs.