The potential of provitamin A-biofortified maize and sweet potato, and bambara groundnut for improving the nutritional status of rural communities in KwaZulu-Natal, South Africa.
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Date
2020
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Abstract
The double burden of malnutrition, under- and over-nutrition, is a serious health problem and a leading contributor to the global disease burden. Undernutrition presents as wasting, stunting, underweight and micronutrient deficiencies, such as vitamin A, iron and zinc, while over-nutrition presents as overweight, obesity and several non-communicable diseases. Children under the age of five years and pregnant women are the most affected by malnutrition, especially in rural areas. In developing countries, such as South Africa (SA), the major contributing factors to all forms of malnutrition are poverty, food and nutrition insecurity as well as the shift from traditional diets to more westernised diets. There have been several strategies employed in SA to alleviate malnutrition, especially vitamin A deficiency (VAD), yet it still remains a problem. Provitamin A (PVA)-biofortified crops could be used as a complementary strategy to address VAD; however, there are challenges of poor consumer acceptability. The poor acceptability of PVA-biofortified foods could be improved by combining them with other commonly consumed plant food items and animal food sources such as chicken to produce provitamin A-rich traditional dishes. However, animal food products can be unaffordable to many economically disadvantaged households, thus legumes could be used as an alternative and cheaper protein source. Bambara groundnut is an underutilised indigenous legume that is found in sub-Saharan Africa (SSA). It is a good source of protein and when consumed together with cooked starch-based products, it forms a complementary protein. Therefore, combining PVA-biofortified maize with bambara groundnut could contribute to improving the nutritional status of vulnerable population groups in SSA, including SA.
Cream-fleshed sweet potato (CFSP) (Ipomoea batata L.) is a commonly consumed crop in SA and would be ideal for PVA-biofortification to produce orange-fleshed sweet potato (OFSP). Unlike PVA-biofortified maize that showed poor consumer acceptability, OFSP has been found acceptable to consumers. The OFSP has a high PVA carotenoid concentration, therefore it could be used as a food-based approach to address VAD among the economically disadvantaged population groups who are usually at risk of VAD, particularly rural communities.
Research conducted on the nutritional composition and consumer acceptability of composite dishes made with PVA-biofortified maize and OFSP is limited, especially in SA. Furthermore, there is paucity of literature on the nutritional composition and consumer acceptance of bambara groundnut combined with cooked PVA-biofortified maize. Thus, this study
investigated the potential of PVA-biofortified maize and sweet potato, and bambara groundnut for improving the nutritional status of rural communities in KwaZulu-Natal (KZN), SA.
In order to formulate an effective food-based approach to address malnutrition, the nutritional status and dietary patterns of the target population group/s (communities) needed to be determined. Thus, the first study objective was to assess the nutritional status, using selected anthropometric indices and dietary intake methods, of four rural communities in KZN, who had been selected for investigating the proposed food-based nutrition approach. Purposive sampling generated a sample of 50 households each in four rural areas of KZN: Swayimane, Tugela Ferry and Umbumbulu and 21 households at Fountain Hill Estate. Anthropometric [height, weight, mid-upper arm circumference (MUAC), and waist circumference] and dietary intake data (repeated 24-hour recall and food frequency) were collected. The Food Finder 3 software of the Medical Research Council (MRC), SA, was used to analyse dietary intake data, and the Statistical Package for Social Sciences (SPSS, version 25) was used to analyse the other data sets. The Estimated Average Requirement (EAR) cut-point method was used to assess the prevalence of inadequate nutrient intake. The results of the study indicated that 17.9 % (n=7), 30.8% (n=12) and 15.5% (n=6) of the children under five years were underweight, stunted and overweight, respectively. According to the MUAC measurements, 20.5% (n=8) and 5.1% (n=2) of the children under five years had severe acute malnutrition (SAM) and moderate acute malnutrition (MAM), respectively. The Fisher’s Exact test showed that a significant proportion (37.5%; n=3) of those with a MUAC below 11.5 cm had a weight-for-height (WFH) Z-score below -3 standard deviation (SD) of the WHO child growth standards median, indicating severe malnutrition (p=0.046). The majority of the adult participants were either overweight (23.6%; n=76) or obese (29.5%; n=95), with a higher prevalence of overweight and obesity among females than males. According to the Binomial test, a significant number (67.0%; n=213) of adult participants had waist circumference measurements below 88 cm and 102 cm for females and males, respectively (p<0.05). The Chi-square test indicated that there was a significant relationship between gender and waist circumference (p<0.05). A significant proportion of adult males (92.9%; n=105) had a normal waist circumference and were not at risk of obesity-related diseases, whilst a significant proportion (p<0.05) of adult females (47.3%; n=97) were at risk of obesity-related diseases, such as diabetes, high cholesterol and hypertension. Adult participants that were underweight or had a normal body mass index (BMI) were not at risk of co-morbidities and obesity, whilst participants who were classified as obese class I, II and III had a high risk of co-morbidities (p<0.05).
Although not statistically significantly different, there was a higher prevalence of over-nutrition than undernutrition at all four research sites for females aged 16-35 years old. There was a significant relationship between BMI and the risk of having a clinically undesirable waist circumference (p<0.05). There was frequent consumption of food items high in carbohydrates (mainly the cereal grain foods), and low intake of micronutrients and fibre by most age groups. The food frequency results indicated that onion, phutu, brown bread, tomato, rice, apple, eggs and chicken were the most commonly consumed food items. Results of analysis by the EAR-cut point method indicated that, among most of the age groups, there was a high prevalence of inadequate intake of several nutrients, including dietary fibre, vitamins, including vitamin A and minerals, including zinc and iron.
The second study objective was to determine the effect of replacing white maize and CFSP with PVA-biofortified maize and OFSP, respectively, on the nutritional composition of traditional and indigenous dishes of KZN, SA. The phutu combinations were selected based on a survey conducted in four selected rural study sites in KZN to determine popular dishes in which maize was combined with other food items. Popular indigenous knowledge systems (IKS)-based recipes were collected to determine methods of preparing and processing white maize and CFSP into food products. Phutu (traditional crumbly porridge) was selected as the cooked maize meal dish, curried cabbage as a vegetarian dish and curried chicken as a meat dish. Curried bambara groundnut was selected as an alternative animal protein source. Grains of one PVA-biofortified maize variety and one white variety (control) was cooked into phutu. Both varieties of phutu were served with either curried cabbage, chicken or bambara groundnut. Two types of boiled sweet potato were used in the study; OFSP and CFSP (control). Composite dishes were prepared by combining either PVA-biofortified phutu or white phutu with other food items, separately, i.e. curried cabbage, curried chicken and curried bambara groundnut and the nutritional composition of the dishes were analysed. Generally, the proximate composition of the PVA-biofortified phutu composite dishes were not significantly different from those of white phutu composite dishes (controls) (p>0.05). However, the PVA concentration of PVA-biofortified phutu composite dishes was higher than that of the white phutu composite dishes (controls). The OFSP had a significantly lower protein concentration, but was significantly higher in other nutrients, including PVA relative to the CFSP (p<0.05).
The third investigation determined the effect of replacing white maize and CFSP with PVA-biofortified maize and OFSP, respectively, on the sensory properties and consumer acceptance of traditional and indigenous dishes of KZN, SA. The sensory acceptability of the composite
dishes and sweet potatoes was evaluated by 60 participants each from the two rural areas (Swayimane and Umbumbulu), using a five-point facial hedonic scale and a paired preference test. Focus group discussions (FGDs) were conducted with 56 participants recruited from the consumer panel to assess consumer perceptions about the composite dishes made with PVA-biofortified phutu and OFSP. The majority of the participants rated the composite dishes containing PVA-biofortified phutu as “good” and the acceptability of the composite dishes varied significantly (p<0.05). Compared to other age groups, the 50-59 year age group showed a higher preference for the white phutu and curried chicken composite dish, whereas the 30-39 year age group showed a higher preference for the PVA-biofortified phutu and curried chicken composite dish. The acceptability of OFSP and CFSP was similar. The FGDs indicated that participants had positive perceptions of the PVA-biofortified phutu when served with curried chicken or cabbage. However, they had mixed perceptions when served with curried bambara groundnut. The older FGD participants perceived that some of the composite dishes, such as phutu and curried bambara groundnut, would not be acceptable to younger consumers as they were not accustomed to bambara groundnut, especially its sensory attributes such as taste, texture and aroma. There were positive responses to the proposal to replace the CFSP with OFSP. Most of the FGD participants perceived the OFSP to be butternut due to its orange colour, sweet taste and visual appeal. The FGD participants expressed a willingness to grow and purchase the PVA-biofortified maize and PVA-biofortified OFSP, if planting materials were made available or if the two types of biofortified crops were available in the local markets for utilisation as staple foods.
The study findings show that under- and over-nutrition, and poor dietary diversity are prevalent in rural KZN. There was a low intake of several nutrients, including dietary fibre and several micronutrients. The study findings indicate that there is a need to increase the availability, accessibility, and utilisation of diverse foods through appropriate agricultural and nutritional interventions. Biofortification could be used as a complementary strategy to assist with the alleviation of VAD in SSA. Although, in several studies, PVA-biofortified foods have been found less acceptable compared to counterpart white maize foods, the PVA-biofortified foods investigated in this study were perceived positively by most of the participants. Overall, the study findings suggest that PVA-biofortified maize and OFSP can replace white maize and CFSP, respectively, in selected traditional dishes of the rural communities studied, to alleviate VAD. Further research should be conducted using a larger sample size, larger area and with
different PVA-biofortified maize food types and varieties of OFSP, to obtain results for large rural populations in all provinces of SA.
Description
Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.