The impact of an orange-fleshed sweet potato yoghurt on the nutritional status of pre-school children in Durban, South Africa

Abstract

Background: Malnutrition exists globally due to various factors including basic, underlying and immediate factors. Goal two of the global targets in the 2030 Agenda for Sustainable Development is to end hunger and ensure that even the poorest people have access to sufficient, nutritious and safe food all year round. The Department of Social Development (DSD) in South Africa identified Early Child Development (ECD) centres as an ideal platform for implementing strategies aimed at improving the wellbeing of children below five years of age. ECD centres are facilities designed to provide early childhood development services and programmes that include good health, proper nutrition and early learning, through a holistic approach in promoting a healthy environment that is conducive for learning and development. Rationale and objectives: The health and nutritional status of young children is a global priority, as indicated in the 2030 Agenda for Sustainable Development. The arguments in favour of promoting the development of children at a very young age are clear and compelling. Effective interventions aimed at the vulnerable groups can make a positive contribution towards the achievement of Sustainable Development Goal (SDG) 2 which aims to end hunger, achieve food security and improved nutrition and promote sustainable agriculture. Inadequate nutrition in young children not only affects physical growth and development, but mental functioning as well. The pre-school years are associated with a phase of rapid growth. Adequate nutrition during the pre-school years is critical as proper nutrition plays an essential role in preventing malnutrition and other childhood-related diseases. Dietary diversification is one of the most effective strategies in preventing malnutrition and it is recommended that it is implemented during the stage of complementary feeding. Diets lacking dietary diversity lead to inadequate intake of vital nutrients such as vitamin A and iron, which may result in micronutrient deficiencies. Vitamin A and iron deficiencies are common among pre-school children in South Africa (SA) and the orange-fleshed sweet potato (OFSP) was identified as a potentially effective strategies to address vitamin A deficiency (VAD). The purpose of the study was to determine the nutrient intake, to develop and test the impact of an OFSP yoghurt on nutritional status of pre-school children in Durban, KwaZulu-Natal, SA, by determining the vitamin A and iron status of preschool children. The objectives of the study were to establish the socio-demographic profile of the children, to take anthropometric measurements (weight and height) to establish their nutritional status, to assess the dietary intake using a 24-hour recall questionnaire, (which was repeated three times) and a Food Frequency Questionnaire (FFQ). Furthermore, the study also aimed to determine the levels of vitamin A and iron in the blood at the time of the study using the finger-prick dried blood spot method, develop a yoghurt using an OFSP, administer the yoghurt as an intervention for three consecutive months and thereafter test the impact of the yoghurt on the nutritional status of the participants. Methodology: In this intervention trial, two ECD centres, an experimental group (EG) and control group (CG) comprising of 116 children aged 24–60 months were randomly selected. In each group, the participants were stratified according to age: 24–47 months and 48–60 months. At baseline, through the caregiver of the child participant, socio-demographic data was captured, and dietary intake was measured through three 24-hour dietary recall questionnaires, which were then analysed using Food Finder® software version 3.0 developed by the South African Medical Research Council (SAMRC). The food frequency questionnaire was used to calculate the food variety and food group diversity scores. Anthropometric measurements (weight and height) were taken and the World Health Organization (WHO) Anthro software® version 3.1 was used to convert these into nutritional data indices. Blood samples were collected through dried blood spot cards in order to determine serum retinol and haemoglobin (Hb) levels, which were assessed using the WHO indicators. A yoghurt with OFSP was developed following the steps of product development. The participants in the EG were given 100g of the developed OFSP yoghurt daily for three months, while the participants in the CG were given 100g of a peach flavoured yoghurt bought from the supermarket daily for three months, excluding weekends. The peach flavour was chosen for the CG as the colour was closest to the developed OFSP yoghurt. After the intervention period, anthropometric measurements were taken, dietary intake was assessed and blood samples were taken to assess impact on serum retinol and Hb levels. Results: Regarding the socio-demographic profile, unemployment was high, as 45.6% (n=36) and 54.1% (n=20) of the participants in the EG and CG respectively, were unemployed. In terms of household characteristics, 45.6% (n=36) of the participants in the EG and 32.4% (n= 12) in the CG had a tap inside the house. Access to a flush/sewage toilet was very limited in both groups, as less than half of participants had a flush toilet (39.2%; n=31) and 40.5% (n=15) in EG and CG, respectively) and more than half of the participants had a pit latrine (60.8%; n=48) in the EG and 59.5% (n= 22) in the CG. At baseline, anthropometric results in the current study showed that 16.6% (n=2) of CG girls 48-60 months of age were stunted. Among boys, 10.5% (n=12) and 36.4% (n=4) of EG and CG boys 48-60 months of age respectively, were stunted. No change was noted among EG boys 24-47 months of age of age, as 4.8% (n=1) were severely stunted at baseline and at endline. At baseline, 8.7% (n=2) of EG girls 24-47 months of age were overweight. In the CG group, 28.6% (n=2) and 16.7% (n=2) of girls 24-47 months of age and 48-60 months of age, respectively, were overweight. Furthermore, 9.5% (n=2) of EG boys and 42.8% (n=3) of CG boys 24-47 months of age were overweight. The prevalence of overweight among boys 48-80 months of age was 10.5% (n=2) and 27.3% (n=3) in the EG and CG, respectively. The prevalence of the risk of overweight increased from 21.7% (n=5) among EG girls 24-47 months of age at baseline to 45.0% (n=9) at endline and from 14.3% (n=1) to 28.6% (n=2) in the CG group. In the CG, an increase in the prevalence of the risk of overweight was noted among boys 48-60 months of age from 36.3% (n=4) at baseline to 54.5% (n=6) at endline. At baseline, the energy intake of girls and boys 24-47 months of age was more than the estimated energy requirement (EER) for both groups, whereas for the 48-60 month age group, it was less than the EER. The mean intake of fibre and calcium was lower than the recommended dietary allowance (RDA) for all groups and most participants consumed less than the RDA for fibre and calcium. The mean fruit and vegetable intake was less than the WHO recommendation of 320g to 480g per day for 24-47 month old children, and 400g to 480g for 48-60 month old children for all participants in the current study, and there was low variety in both groups. When comparing baseline with endline results between age groups within a group, there was a decrease in energy intake in all groups. Significant differences were found among EG girls 24-47 months of age (p=0.008) and CG girls (p=0.003 for 24-47 months and p˂0.001 for 48-60 months) for energy intake. Furthermore, baseline results showed that 2.7% (n=2) and 14.3% (n=3) of participants had low serum retinol levels in the EG and CG, respectively. At endline, serum retinol increased in 5.5% (n=3) of participants in the EG and 4.5% (n=1) in the CG. Low Hb levels were found in 19.2% (n=14) of participants in the EG and 32.1% (n=9) in the CG. At endline, Hb levels increased in 3.7% (n=2) and 9.0% (n=2) of participants in the EG and CG, respectively. Conclusion: Despite the numerous efforts to improve the nutritional status of children, a high prevalence of malnutrition still exists in South Africa. Consumption of the OFSP yoghurt made a small contribution to dietary vitamin A intake for some participants and iron intake levels did not increase from baseline to endline. The intervention period was too short to show an impact on anthropometric measurements such as stunting. The socio-demographic profile indicated that participants were predominantly from low-income households, and deprived of some essential sanitation services. Other issues in the current study population included overcrowding and high unemployment, with some households running out of money to buy food. The diet of the participants, was sub-optimal for optimum growth. Malnutrition, presented through micronutrient deficiencies, stunting, overweight and obesity, co-exist in this vulnerable population.