Chapter 2- Literature review
2.1. Introduction
2.1.4 VAD remediation strategies and their shortcomings
As a strategy for combating VAD, dietary diversification aims at increasing production and consumption of vitamin A-rich foods, ensuring its bioavailability in the diet and making vitamin
23 A-rich foods available and accessible to populations in need. This can be achieved by behaviour change that aims at improving communication through social marketing and nutrition education, horticultural approaches e.g. home food gardens and ways of retaining vitamin A content of food by examining the preparation and cooking methods (Faber and Wenhold 2007). Dietary diversification has been successful in reducing VAD in South Africa, because of increased consumption of foods rich in vitamin A through home gardening together with awareness campaigns in affected areas (Faber et al. 2009). However, in poor rural consumers, dietary diversity is inhibited by the availability of resources at household level and seasonality of certain foods such as fruits and vegetables e.g. vitamin A intake among Kenyan pre-school children from low-income rural households considerably differed between post-harvest and lean months (Dary and Mora 2002). Dietary diversity has also been identified as a different and expensive strategy to maintain on a large scale (Faber et al. 2009).
2.1.4.2 Vitamin A supplementation
Vitamin A supplementation is another strategy used for combating VAD. It involves the provision of vitamin A capsules containing retinol, which is stored in the liver and is released, slowly in sufficient quantity to sustain vitamin A requirements for six months (Meenakish et al.
2009). A dose of 50 000 International Units (IU) is recommended for infants less than six months of age, 100 000 IU for infants six to 11 months of age and 200 000 IU for children aged 12 months to five years (DOH 2012). In areas where VAD is a health problem WHO recommends that children between six to 59 months should receive supplementation.
Supplementation is the fastest way of controlling VAD in individuals or population groups that vulnerable. Supplementation also reduces child mortality by improving gut integrity thereby reducing diarrhoeal episodes and susceptibility to infections (WHO 2011).
There is however recurrent of VAD if supplementation is used for a long period of time The supplementation programme carried out in 103 priority countries has shown a coverage stagnated at 58%, with high annual fluctuation (WHO 2011). Some side effects associated with supplementation include headache, nausea and vomiting among children aged six to 59 months,
24 although the symptoms disappear within 24 hr of infant or child receiving the supplement (WHO 2011). The sustainability of supplementation has also been questioned. This is in support of a study conducted by van Stuijvenberg et al. (2011) which concluded that the blanket approach of administering vitamin A may not be appropriate for all areas of the country, even if the community is malnourished and poverty-stricken. Although the global cost of vitamin A capsule has been estimated to be $US0.10, logistics and distribution cost makes the cost of the capsule to be more expensive, at $US1.00 (Nestle et al. 2006).
2.1.4.3 Vitamin A fortification
Several food vehicles including vegetables oil, margarine, milk and other dairy products, cereal flours, sugar, infant formulas, and complementary foods for children have been used for fortification with vitamin A. Vitamin A is fat soluble hence high fatty foods can easily be fortified with vitamin A (Sherwin et al. 2012). Vitamin A fortification does also not require the target groups to change their dietary behaviours as in dietary diversification. However, to get the required level of vitamin A, it needs to be consumed in adequate amounts by a large proportion of the target individuals. In 2013, VAD in South African children less than five years of age decreased by 20% on a national level as a result of vitamin A fortification (Shisana et al. 2013).
The retinol concentrations of children aged 6-59 months fed with vitamin A fortified milk and cereal was found to be higher than those fed non-fortified milk and cereal (Eichler et al. 2012).
However, vitamin A fortification has limitations due to low accessibility of commercially vitamin A-fortified foods to poor people in rural areas (Faber and Wenhold 2007; Nestel et al.
2006). In South Africa the fortification of maize meal with seven micronutrients including vitamin A, faces the challenge of low compliance by food manufacturers with the SA regulations as well as poor adherence to the WHO recommendations. Food fortification also changes the sensory characteristics of food, which may pose a challenge on the consumer acceptance of these foods. Bioavailability of food is reduced because of food fortification (Papathakis and Pearson 2012).
25 2.1.4.4 Biofortification of staple crops with provitamin A carotenoids
Biofortification of staple crops with PVA carotenoids is currently being evaluated as a complementary strategy to address VAD in SSA (Tanumihardjo 2008). It is achieved by either agronomic, convectional or transgenic breeding (Saltzman et al. 2013). Currently, the HarvestPlus Challenge Programme has a biofortification programme in place that makes use of conventional breeding of staples crops such as maize, cassava, sweet potato and plantain with PAV carotenoids (Bouis et al. 2011b). Biofortification efforts are showing successes in improving the vitamin A status of the poor rural populations in several countries e.g. orange fleshed sweet potato (OFSP) have been shown to be efficacious and effective at improving the vitamin A status of children in Mozambique, Uganda and Nigeria (Low et al. 2007; Hotz et al.
2012). PVA-biofortified crops are not associated with vitamin A toxicity due to the body’s ability to convert carotenoids to vitamin A as needed (Stevens and Winter-Nelson 2008). In plant breeding, biofortification is one-time investment as the investment pays by yielding micronutrient rich crops. Varieties bred for one country can also be evaluated and used in other countries which multiples the benefits of the initial investment. It has been reported that the ongoing expenses for monitoring and maintaining these crops, are far lower than the initial costs of the crops (Bouis et al. 2011). Biofortification is also scientifically viable as well as cost effective because once the crop has been biofortified the cost of biofortification are far lower than industrial fortification or supplementation (Mayer et al. 2008).
Biofortified crops are however unable to deliver a high quantity of macronutrients as compared to vitamin A capsules as well as industrially vitamin A-fortified foods (Saltzman et al. 2013).
Biofortification also results in an alteration of the sensory characteristics of the crop thereby presenting a challenge with consumer acceptance of the crop (Muzhingi et al. 2008). It was also predicted by the HarvestPlus Programme that it will take a decade for biofortified crops to be adopted in the Global South due to obstacles such as individual property rights, public and government acceptance and safety issues. As a result of these obstacles, transgenic approaches to biofortified crops are costly and take significant amounts of time before being released to
26 farmers in many countries (Meenakshi et al. 2012). The next section discusses the importance of maize as a human food in SSA.