Research Article

Provitamin a Yellow Cassava: A key Strategy to Alleviating Vitamin A Deficiency in the Tropics

Olarewaju M Oluba

Department of Biological Sciences, Food Safety and Toxicology Research Unit, Landmark University, Nigeria

Submission: October 26, 2018;Published: March 22, 2019

*Corresponding author: Olarewaju M Oluba, Department of Biological Sciences, Food Safety and Toxicology Research Unit, Environment and Technology Research Cluster, College of Science and Engineering, Landmark University, P.M.B. 1001, Omu Aran, Kwara State, Nigeria

How to cite this article: Olarewaju M Oluba. Provitamin a Yellow Cassava: A key Strategy to Alleviating Vitamin A Deficiency in the Tropics. Nutri Food Sci Int J. 2019. 8(4): 555742 DOI: 10.19080/NFSIJ.2019.08.555742.

Abstract

The significance of biofortification β-Carotene-biofortified cassava produced through plant breeding as a sustainable agronomic approach to alleviate vitamin A deficiency. VAD is observed to be prevalent in tropical regions of the world where cassava is a staple crop and forms a major component of the daily food intake Therefore, cassava biofortification intervention focused on alleviating VAD in rural areas has advantages over supplementation and fortification because the provitamin A biofortified yellow cassava can provide a sustainable source of β-carotene, a potent precursor of vitamin A which is easily converted to retinol in vivo in humans thus improving their vitamin A status. It is hope that with the much-needed support from governmental and donor agencies as well as increase research attention, the provitamin A biofortified cassava remains a viable alternative in addressing VAD in the tropics.

Keywords:Vitamin A deficiency; Biofortification; Provitamin A yellow cassava

Introduction

Vitamin A deficiency disease (VAD) remains a public health challenge in developing countries. VAD primarily affects preschool children and women with an estimated 3.3 million preschool children in Africa affected each year. Reports have shown that over 10% of affected children become either partially or totally blind [1-4]. The requirement for vitamin A in women increases in pregnancy, and at present over 20 million pregnant women in developing countries are vitamin A deficient. Approximately 6 million vitamin A-deficient women show clinical signs of night blindness and close to 600,000 mortality cases in pregnancy have been attributed to VAD annually [4,5]. Vitamin A deficiency (VAD) impairs human vision and damages the immune, respiratory, and reproductive systems. Consequently, individuals suffering from VAD are characterized by weak immune systems and are at a more considerable risk of dying from measles, diarrhoea or malaria [6].

Vitamin A plays a fundamental role in supporting growth, reproduction, and embryonic development, as well as in regulating cell differentiation and proliferation, and maintains an important function in the immune system. Vitamin A is an essential nutrient in mammalian nutrition. It occurs in several forms including retinol, retinal, retinoic acid and the provitamin A carotenoids (Figure 1). These variable forms of vitamin A are collectively called retinoids. In the process of vision, retinal combines with the protein opsin to form rhodopsin which is the light-absorbing molecule [7]. In plants, vitamin A occurs as provitamin A carotenoids (precursors of retinol), which are converted into retinol in vivo. There are over 600 naturally occurring carotenoids of which only 3 are important precursors of vitamin A in humans. These include, α-carotene, β-carotene and β-cryptoxanthin [8]. β-carotene, aside being the most abundant carotenoid in foods, is nutritionally the most potent precursor of vitamin A [9]. These provitamin A carotenoids are found in green leafy vegetables (including spinach, amaranth; yellow vegetables including pumpkins, squash, and carrots; and yellow and orange non-citrus fruits including mangoes, apricots, and papaya [1].

Mammals lack the capacity to synthesize vitamin A de novo thus the daily requirement by the body to meet physiological needs and functions must be obtained from the diets. However, low intake vitamin A could result in vitamin A-deficiency with its attendant health implications [3].

Several intervention strategies have been advanced to addressing the devastating consequences of VAD in children and women [10]. As part of these efforts, the yellow-fleshed provitamin A-biofortified cassava was introduced recently as a sustainable strategy to increasing the dietary intake of vitamin A especially in rural communities where supplementation has not been successful. The provitamin A cassava cultivars have been genetically modified using the traditional plant breeding tools to accumulate high levels of pro-vitamin A and other pro-vitamin A carotenoids [6,11-13]. These new cassava varieties are 25% higher in β-carotene and are capable of providing up to 40% of vitamin A recommended daily allowance (RDA) for children who are vulnerable to VAD [10,14,15]. It has also been established that provitamin A biofortified cassava is capable of retaining a large proportion of its provitamin A content and thus providing 100% more β-carotene than the indigenous white sweet cassava (unpublished data) (Figure 1).

Since its introduction in 2005 in Nigeria, efforts have been geared towards aggressive advocacy and education by extension workers on the nutritional and health benefits of these new cassava varieties. Stem cuttings of the provitamin A cassava varieties are distributed freely to local farmers. It is hope that this approach will offer a cost-effective, renewable means to reduce micronutrient deficiencies as opposed to vitamin A supplementation [12]. Overall, biofortification is expected to have a far-reaching health implication across the different strata of the society, including children and women who are most susceptible to VAD [10].

Results on the experimental validation of the effectiveness of provitamin A cassava in improving the vitamin A status of volunteers have been impressive. In a study by Talsma et al. [17] daily consumption of β-carotene biofortified cassava fed as porridge to Kenyan schoolchildren with marginal vitamin A status was observed to produce modest increase in serum retinol concentration and large increases in β-carotene concentration compared with children fed white cassava. However, increase research attention is required to bring to limelight the potential nutritional and health-promoting attributes of this novel cassava varieties

In conclusion, provitamin A biofortified cassava offers a feasible and viable strategy of improving the vitamin A status of VAD of the poor and vulnerable women and children in very remote rural communities in the tropical regions of the world where cassava is a staple crop and forms a major component of the daily food intake.

References

1. FAO/WHO (2005) Codex Standard for Sweet Cassava. Codex Standard 238-2003. Food and Agriculture Organization and World Health Organization of the United Nations, Rome, Italy.
2. Bowley A (2008) Alliances against hunger. Editorial Nutriview 4. p. 2
3. Arlappa N, Balakrishna N, Laxmaiah A, Raghu P, Rao VV (2011) Prevalence of vitamin A deficiency and its determinants among the rural pre-school children of Madhya Pradesh, India. Ann Hum Biol 38(2): 131-136.
4. World Health Organization (2014) UNICEF Trends in maternal mortality: 1990 to 2013: estimates by WHO, UNICEF, UNFPA, The World Bank and the United Nations Population Division: executive summary.
5. Failla ML, Chitchumronchokchai C (2005) In vitro models as tools for screening the relative bioavailabilities of provitamin A carotenoids in foods. International Food Policy Research Institute, Washington, DC, USA.
6. De Moura FF, Miloff A, Boy E (2015) Retention of provitamin A carotenoids in staple crops targeted for biofortification in Africa: cassava, maize and sweet potato. Crit Rev Food Sci Nutr 55(9): 1246-1269.
7. Sugihara M, Buss V, Entel P, Elstner M, Frauenheim T (2002) 11-cis-retinal protonated Schiff base: influence of the protein environment on the geometry of the rhodopsin chromophore. Biochemistry 41(51):15259-66.
8. Ching LS, Mohamed S (2001) Alpha-tocopherol content in 62 edible tropical plants. J Agric Food Chem 49(6): 3101-3105.
9. Teixeira EM, Carvalho MR, Neves VA, Silva MA, Arantes-Pereira L (2014) Chemical characteristics and fractionation of proteins from Moringa oleifera Lam. leaves. Food Chem 147: 51-4.
10. Bouis HE, Hotz C, McClafferty B, Meenakshi JV, Pfeiffer WH (2011) Biofortification: A new tool to reduce micronutrient malnutrition. Food Nutr Bull 32(Suppl 1): S31-S40.
11. Sayre R, Beeching JR, Cahoon EB, Egesi C, Fauquet C, et al. (2011) The BioCassava plus program: biofortification of cassava for sub-Saharan Africa. Ann Rev Plant Biol 62: 251-272.
12. Pfeiffer WH, McClafferty B (2007) HarvestPlus: breeding crops for better nutrition. Crop Sci 47: S88 -S105.
13. La Frano MR, Woodhouse LR, Burnett DJ, Burri BJ (2013) Biofortified cassava increases β-carotene and vitamin A concentrations in the TAG-rich plasma layer of American women. Br J Nutr 110(2): 310-320.
14. Oluba OM, Oredokun‐Lache AB, Odutuga AA (2018) Effect of vitamin A biofortification on the nutritional composition of cassava flour (gari) and evaluation of its glycemic index in healthy adults. J Food Biochem 42(4): e12450.
15. Oluba OM, Oredokun‐Lache AB (2018) Nutritional composition and glycemic index analyses of vitamin A‐biofortified maize in healthy subjects. Food Sci Nutr 6(8): 2285-2292.
16. Bai C, Twyman RM, Farré G, Sanahuja G, Christou P, et al. (2011) A golden era-pro-vitamin A enhancement in diverse crops. In Vitro Cell Develop Biology-Plant, 47(2): 205-221.
17. Talsma EF, Brouwer ID, Verhoef H, Mbera GN, Mwangi AM, et al. (2015) Biofortified yellow cassava and vitamin A status of Kenyan children: a randomized controlled trial. Am J Clin Nutr 103(1): 258-267.