Research Article: Micronutrient adequacy is poor, but not associated with stunting between 12-24 months of age: A cohort study findings from a slum area of Bangladesh

Date Published: March 29, 2018

Publisher: Public Library of Science

Author(s): Kazi Istiaque Sanin, M. Munirul Islam, Mustafa Mahfuz, A. M. Shamsir Ahmed, Dinesh Mondal, Rashidul Haque, Tahmeed Ahmed, Jacobus P. van Wouwe.

http://doi.org/10.1371/journal.pone.0195072

Abstract

The prevalence of stunting among children below 5 years of age is higher in the slum-dwelling population of Bangladesh compared to that in both urban and rural areas. Studies have reported that several factors such as inadequate nutrition, low socio-economic status, poor hygiene and sanitation and lack of maternal education are the substantial predictors of childhood stunting. Almost all these factors are universally present in the slum-dwelling population of Bangladesh. However, few studies have prospectively examined such determinants of stunting among slum populations. In this paper, we reveal the findings of a cohort study with an aim to explore the status of micronutrient adequacy among such vulnerable children and establish its association with stunting along with other determinants. Two-hundred-sixty-five children were enrolled and followed since birth until 24 months of age. We collected anthropometric, morbidity and dietary intake data monthly. We used the 24-hour multiple-pass recall approach to collect dietary intake data from the age of 9 months onward. Micronutrient adequacy of the diet was determined by the mean adequacy ratio (MAR) which was constructed from the average intake of 9 vitamins and 4 minerals considered for the analysis. We used generalized estimating equation (GEE) regression models to establish the determinants of stunting between 12–24 months of age in our study population. The prevalence of low-birth-weight (LBW) was about 28.7% and approximately half of the children were stunted by the age of 24 months. The average micronutrient intake was considerably lower than the recommended dietary allowance and the MAR was only 0.48 at 24 months of age compared to the optimum value of 1. However, the MAR was not associated with stunting between 12–24 months of age. Rather, LBW was the significant determinant (AOR = 3.03, 95% CI: 1.69–5.44) after adjusting for other factors such as age (AOR = 2.12, 95% CI: 1.45–3.11 at 24 months and AOR = 1.97, 95% CI: 1.49–2.59 at 18 months, ref: 12 months) and sex (AOR = 1.98, 95% CI: 1.17–3.33, ref: female). Improving the nutritional quality of complementary food in terms of adequacy of micronutrients is imperative for optimum growth but may not be adequate to mitigate under-nutrition in this setting. Further research should focus on identifying multiple strategies that can work synergistically to diminish the burden of stunting in resource-poor settings.

Partial Text

Globally, chronic undernutrition manifested by stunting (height or length-for-age Z-score < -2SD) affected 159 million children under five-year-old in 2014 [1]. Stunting is a huge burden particularly for the low and middle-income countries (LMICs) [2]. Asia remains the continent with the highest number of stunted children (approximately 100 million) while, in Africa, the prevalence remains stagnant at around 40% [3]. While a defined pathway of stunting remains ambivalent, it is presumed to be an outcome of complex interactions among diverse factors, such as inadequate nutrition, repeated infection, intrauterine growth restriction [4,5] and so on. A significant proportion of stunting in LMICs occurs during 6–24 months of age [6,7], a period when complementary foods are introduced in children’s diet. During this time, the nutritional requirement becomes much higher due to both physiological and pathological factors such as rapid growth, limited gastric capacity and frequent exposure to pathogens [8]. To meet this increased demand, optimum breastfeeding, as well as a wider range of safe and nutrient-dense foods must be provided [9] for appropriate physical growth and neurodevelopment [8]. Total 265 children (130 males and 135 females) were enrolled in this study (Table 3). However, we have complete information on 234, 225 and 214 children at 12, 18 and 24 months of age respectively (Fig 1). The prevalence of LBW was 28.7%, and female children had 2-fold greater odds (OR = 2.3, 95% CI 1.32–4.0) of being low birth weight compared to male children. Considering LAZ, 21 male and 27 female (total 18%) were stunted at birth. At birth, mean LAZ was -1.08, mean WAZ was -1.31 and mean WLZ was -0.96. The mean LAZ of the participants further worsened with age and was -1.65, -1.95 and -2.03 at 12, 18 and 24 months, respectively. By 24 months of age, almost half of all the children (47.9%) became stunted (Table 3). No statistically significant association was found between gender and stunting status at any particular age using bivariate analysis (Chi-Square test). The average age of the mothers was approximately 25 years and 33% of them had completed primary education. Additional socio-economic characteristics of the study population are presented in Table 4. Our findings suggest that the prevalence of stunting is high among children less than two years old living in an urban slum area in Dhaka, Bangladesh. It further suggests that the dietary micronutrient adequacy is poor among the study population considering most of the micronutrients included in the analysis. However, we did not find any evidence suggesting a plausible causal association between poor micronutrient adequacy and stunting among the studied children between 12–24 months of age. Having a history of LBW was attributed as the prominent risk factor for the development of stunting among these children after adjusting for other predictors in a slum area of Bangladesh. The key strength of our study findings is the study design and subsequent statistical analysis. The majority of the studies that aim to identify nutrient adequacy and its association with growth faltering have been conducted using a cross-sectional design at a single time point. However, in our study, due to the cohort design, we have measured and subsequently accumulated all the information multiple times prospectively, indicating the temporal sequence between the predictor and outcome variables. Such repeated measurement enabled us to estimate and report the typical dietary intake in the population. In our statistical analysis, we used the appropriate method to account for repeated measurement of multiple variables of interest, which has further strengthened our study findings. The degree of micronutrient adequacy of the complementary food is deficient for most vitamins and minerals among children below two years of age in a slum-dwelling population of Bangladesh. However, such inadequacy does not account for the high prevalence of stunting that was observed in the study. Rather, history of low birth weight is the prominent determinant of stunting among these slum-dwelling children, after adjusting for other factors. Improving the nutritional quality of the complementary food is imperative for optimum growth. However, this may not be sufficient enough to mitigate the burden of stunting in impoverished slums. Further research should focus on identifying multiple strategies that could work synergistically to diminish the burden of stunting in such underprivileged and resource depleted settings.   Source: http://doi.org/10.1371/journal.pone.0195072