Assessment of dietary zinc intake, serum zinc concentration and nutritional status of school children aged 60-120 months in Wakiso District in Central Uganda

Abstract

Introduction School children require adequate diet, rich in energy, macro-and micro-nutrients particularly vitamin A, iron and zinc in order to maintain adequate learning both in and out of school. Despite the importance of zinc for growth, little information and no previous study has been conducted in Uganda on feeding patterns and nutritional status, nor the extent of zinc deficiency amongst school children to help service providers plan for improved resources. This study has determined dietary zinc intake, serum zinc concentration and general nutrition status of a group of Ugandan school children (60-120 months) and the relationships between them together with associated socioeconomic factors in Wakiso District, Central Uganda. Methodology A cross sectional study was undertaken to assess the prevalence of zinc deficiency as well as the general nutritional status of school children aged 60-120 months. The subjects were recruited based on school registers. The sample size was determined using a simple random sampling procedure. Four hundred (400) school children were recruited for the serum zinc concentration study and out of these 364 were sampled for the nutritional status investigation and clinical examination. Out of those recruited for nutrition assessment, 189 mothers/caters were also interviewed about their socioeconomic status, the feeding and morbidity patterns of their children plus any knowledge they might have on the importance of zinc nutrition. The variables collected on the children were: age, sex, weight, height, MAUC, dietary zinc intake, serum zinc concentration and morbidity. Serum zinc was determined by Atomic Absorption Spectrophotometer method at the Kenya Medical Research Institute. Data was analysed using EpiInfo version 6.0 and SPSS version 12. Results and discussion Most of the school children were being fed on cereals and other starchy staples, which are a good source of energy but only moderate source of zinc. Legumes provided the preferred sauce (relish) (relish) used, while other vegetables and foods of animal origin were consumed less frequently thus increasing the likelihood of a low zinc intake among the school children. Educational level of the mother/caretaker (r=0.632; P=0.049) and number of children cared by the mother/caretaker (r=-0.462; P=0.035) were significantly associated with the number of meals consumed by the child. Insufficient number of meals eaten contributed to the inadequate zinc intake and increased the risk of zinc deficiency among the children. The mean dietary zinc intake among the studied school children was 5.7 mg/day. About one third (32.8%) had an inadequate dietary zinc intake of less than 9 mg/day. The prevalence of zinc deficiency assessed biochemically among the school children was 28.8% of which 12.5% were classified as severely deficient in serum zinc concentration. The prevalence of general malnutrition among the studied school-going children was found to be 13.8% underweight, 22.0% stunting and 2.2% wasting. Serum zinc concentration showed a significant correlation with underweight (r=0.311; P=0.018) and stunting (r=-0.447; P=0.023) but this relationship was not significant for wasting (r=0.115; P=0.157). In the case of stunting, the negative association resulted from some children with a normal height-for-age also being zinc deficient. This implies that a low serum zinc concentration was not the primary limiting factor for the growth of this cohort of children in the present study. Conclusion and recommendations Poor feeding practices were recorded among school children and this contributed to the inadequate dietary zinc intake. General malnutrition amongst the school-going children was common and the prevalence of zinc deficiency was high and did correlate closely with growth status. This level of prevalence of zinc deficiency among school going children in Central Uganda is of public concern. Thus, in any public health investigation, the possibility of zinc deficiency needs to be assessed separately from general anthropometry. To achieve international recommendations for an adequate zinc intake, school-going children should be fed three times a day on a variety of foods. Nutritional screening for zinc deficiency, in addition to growth promotion and monitoring should be strengthened at school, health centres and community levels.