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 Table of Contents  
Year : 2018  |  Volume : 25  |  Issue : 1  |  Page : 13-16

Prevalence of Vitamin A deficiency among under-five children in South-Western Nigeria

1 Department of Paediatrics, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria
2 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria
3 Department of Paediatrics and Child Health, Obafemi Awolowo University, Ile-Ife, Nigeria

Date of Web Publication17-Apr-2018

Correspondence Address:
Dr. Olufunmilola O Abolurin
Department of Paediatrics, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/npmj.npmj_20_18

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Background and Aim: Vitamin A deficiency (VAD) constitutes a major nutritional concern in developing countries. It contributes significantly to the morbidity and mortality of under-five children and can result in impaired resistance to infection as well as increased risk of death. The aim of this study was to determine the prevalence of VAD among Southwestern Nigerian children. Methods: Apparently healthy children aged between 6 months and 5 years were recruited for the study. Their serum retinol levels were determined by high-performance liquid chromatography. Results: Of the 170 children studied, nine (5.3%) had VAD, although none had severe VAD. The prevalence of VAD did not show statistically significant variation with age (P = 0.159), sex (P = 1.000), social class (P = 0.740), immunisation status (P = 0.197) or nutritional status (P = 0.090). Conclusion: The prevalence of VAD among Nigerian children appears to have reduced, compared with previous reports; however, further studies are required to assess the current national prevalence, so as to design programmes that can achieve further reduction in the proportion of children affected.

Keywords: Nigeria, Under-five children, Vitamin A deficiency

How to cite this article:
Abolurin OO, Adegbola AJ, Oyelami OA, Adegoke SA, Bolaji OO. Prevalence of Vitamin A deficiency among under-five children in South-Western Nigeria. Niger Postgrad Med J 2018;25:13-6

How to cite this URL:
Abolurin OO, Adegbola AJ, Oyelami OA, Adegoke SA, Bolaji OO. Prevalence of Vitamin A deficiency among under-five children in South-Western Nigeria. Niger Postgrad Med J [serial online] 2018 [cited 2023 Jan 31];25:13-6. Available from: https://www.npmj.org/text.asp?2018/25/1/13/230196

  Introduction Top

Adequate nutrition is essential for the well-being of children. Micronutrient deficiencies constitute a matter of critical concern among children worldwide but most especially in developing countries.[1],[2] Vitamin A is an essential micronutrient that is important for growth, development, immunocompetence and good vision. It is required for differentiation and restoration of the epithelial tissues in the body as well as normal functioning of the immune system.[3],[4] Vitamin A deficiency (VAD) constitutes a major nutritional concern in the poor communities of the developing world. It is a major contributor to the morbidity and mortality of under-five children and can result in impaired resistance to infection as well as increased risk of death.[3],[5],[6] VAD children who have developed clinical signs are 3–12 times more likely to die than their non-deficient counterparts.[7],[8]

Vitamin A supplementation has been shown to reduce the risk of death in under-five children by about 23%–30%.[5],[9],[10] Guaranteeing a high coverage of supplementation is therefore critical, not only to eliminating VAD as a public health problem but also as a central element of the child survival agenda. It is recommended that all under-five children living in high-risk areas be made to receive high-dose supplements every 6 months to promote substantial reduction in childhood mortality.[5],[11] Indeed, Vitamin A supplementation has been incorporated into the current immunisation schedule in Nigeria by the National Programme on Immunization (NPI), with two doses being given, 6 months apart, during infancy. Vitamin A supplements are also given during some of the National Immunization Days (NIDs), with the aim of further increasing the coverage of supplementation. These interventions are expected to bring about a reduction in the prevalence of VAD among Nigerian children.

The present study was carried out to determine the prevalence of VAD among under-five children in Ilesa, Osun State, Nigeria. The study was expected to generate additional information on the burden of VAD in our community and possibly shed some light on the impact of the various Vitamin A supplementation programmes that have been put in place. The study outcome might also justify advocating for an increase in the current coverage of Vitamin A supplementation, as well as the need to promote modification of children's diet with a view to increasing the Vitamin A content.

  Methods Top

Ethical clearance for the study was obtained from the Ethics and Research Committee of the Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile-Ife, Nigeria, on 17 September, 2015 (protocol number ERC/2014/05/13). The study was commenced in October 2015 and completed in March 2016. It was a descriptive cross-sectional study, which was conducted at the under-five welfare clinic of the Wesley Guild Hospital (WGH), Ilesa, Osun State, Nigeria. The WGH is one of the units of the OAUTHC, Ile-Ife, Osun state, Nigeria.

One hundred and seventy children between the ages of 6 and 59 months, who were apparently healthy, were recruited consecutively into the study. The study population comprised mostly of children who presented for immunisation but also those who came for routine blood tests like haemoglobin genotype and those for minor surgical procedures like herniotomy. Children below the age of 6 months were not included in the study because, according to the WHO, they are not considered a useful group for VAD screening in areas where breastfeeding predominates for at least 4–6 months.[12] Those whose parent(s)/caregiver refused to give consent were also excluded from the study. Children who had ingested Vitamin A supplements within the previous 4 weeks, including those given at immunisation clinic and during NIDs, were also excluded from the study since recent Vitamin A ingestion could cause a transient rise in serum retinol level following absorption of the supplement.[13] History of ingestion of supplements was obtained from the parent(s)/caregivers and the immunisation cards. A written informed consent was obtained from the parent(s) or the accompanying guardian of each of the study participants.

The children were classified into those from high and low social class based on the occupation and level of education of their parents.[14] Children who had received all the recommended immunisations for their age according to the NPI were classified as having complete immunisation, while those who had missed one or more doses were classified as having incomplete immunisation. Anthropometric measurements were obtained, following which the nutritional status of each child was assessed using the WHO child growth standards in the form of Z-scores.[15] Approximately 2.5 mL of blood was collected from each child for retinol assay. The cost of the investigation was borne by the researchers and all materials used were provided at no cost to the participants. Blood samples were collected into plain bottles, and the serum was obtained by centrifugation of the blood at 3000 revolutions/min for 10 min using a clinical macrocentrifuge.

Serum retinol levels were determined by reversed-phase high-performance liquid chromatography (HPLC), using retinyl acetate as an internal standard. The analysis was performed on an Agilent 1100 series ® HPLC machine (Agilent Technologies, Palo Alto, USA) fitted with a quaternary pump and a diode array UV detector. Children who had serum retinol levels below 20.0 μg/dl (0.70 μmol/L) were considered to have VAD, while values <10.0 μg/dl (0.35 μmol/L) were classified as severe VAD. Data analysis was done using the Statistical package for the social sciences software for windows version 17.0 (IBM SPSS Inc., Chicago, IL). Means were compared using the independent samples t-test (t), while proportions were compared using the Pearson's Chi-square test (χ2). The likelihood ratio test or Fisher's exact test was applied to Chi-square analysis as applicable in tables where over 20% of the cells had expected counts <5.[16] Probability values P < 0.05 were accepted as statistically significant.

  Results Top

The ages of the children ranged from 6 to 59 months with a mean of 16.8 ± 9.0 months. [Figure 1] shows the age distribution of the children. Eighty-nine (52.4%) children were male, while 81 (47.6%) were female. One hundred and one (59.4%) were from the low social class, while 69 (40.6%) were from high social class. Four (2.4%) had incomplete immunisation for age, while the remaining 166 (97.6%) were appropriately immunised for age. The prevalence of underweight, stunting and wasting among the study population was 10 (5.9%), 22 (12.9%) and 4 (2.4%), respectively.
Figure 1: Age distribution of the children

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The children had a mean serum retinol level of 1.33 ± 0.38 μmol/L, with values ranging from 0.50 to 2.25 μmol/L. Nine (5.3%) were VAD, but none had severe VAD. There was no statistically significant difference in the prevalence of VAD between children aged ≤24 months and those older than 24 months (P = 0.159). Male children did not differ significantly from the females in their prevalence of VAD (P = 1.000). Six (5.9%) of those from low social class and three (4.3%) of those from high social class had VAD. The prevalence of VAD did not show statistically significant variation with social class (P = 0.740). One (25.0%) of the four incompletely immunised children had VAD, while 8 (4.8%) of those whose immunisation status was appropriate for age had VAD. The difference was also not statistically significant (P = 0.197).

The difference in the prevalence of VAD between children who were underweight (2/10; 20.0%) and those who were not (7/160; 4.4%) was not statistically significant (P = 0.090). Similarly, there was no statistically significant relationship between VAD and stunting as 2 (9.1%) of the 22 children with stunting had VAD, compared with 7 (4.7%) of the 148 children without stunting (P = 0.329). Furthermore, none of the four children who had wasting was VAD, whereas 9 (5.4%) of the 166 without wasting had VAD. The difference was, however, not statistically significant (P = 1.000).

  Discussion Top

The prevalence of VAD in the present study (5.3%) was lower than the prevalence reported by Adelekan et al.[17] (11.3%) from a previous study carried out in a neighbouring community of the present study location. Like in the present study, none of the children studied by Adelekan et al.[17] had severe VAD. The fact that the locations of the two studies were within the same vicinity may suggest that the prevalence of VAD is reducing in the area; however, the earlier study had a much higher prevalence of undernutrition and was a community-based study. Furthermore, differences in the methods of retinol analysis may account for some of the differences as the spectrophotometric method, which was used in the earlier study, may not estimate retinol content as efficiently as the HPLC method.[18]

The prevalence of VAD in the present study was also lower than the prevalence previously reported by Akinyinka et al.[19] (31.6%), Oso et al.[20] (74.6%) and Uzoechina et al.[21] (16.4%), in other parts of the country, as well as the national prevalence reported by Ajaiyeoba [22] (28.1%) and Maziya-Dixon et al.[23] (29.5%). Furthermore, the absence of severe VAD among the children studied may be of significance considering the fact that Akinyinka et al.,[19] Oso et al.[20] and Uzoechina and Okoro [21] reported prevalence of 6.2%, 26.8% and 9.2%, respectively, while Ajaiyeoba [22] and Maziya-Dixon et al.[23] reported the national prevalence of 7.0% and 4.7%, respectively, for severe VAD. These may mean that the prevalence of VAD among Nigerian children is taking a downwards trend.

The administration of Vitamin A supplements during routine childhood immunisation and NIDs might have contributed to reduction in the prevalence of VAD among Nigerian children. However, the suspected reduction would require further validation by carrying out the present-day research on the prevalence of VAD in more regions of the country. The current national prevalence can then be determined and compared with the previous values, which were obtained >10 years ago. The Vitamin A supplementation programmes in the country should be kept alive and further strengthened so as to reach all children, thereby rescuing them from the effects of VAD, with the ultimate goal of reducing the country's under-five mortality rate. Vitamin A-rich food items should also be given regularly to children so as to reduce their risk of VAD.

VAD may not always be apparent, thereby manifesting as a form of 'hidden hunger'.[24] Although a correlation has been established between VAD and protein malnutrition,[3],[25] the present study did not establish a significant relationship between VAD and undernutrition. Similarly, Adelekan et al.[17] did not observe any significant relationship between VAD and anthropometric indices. Thus, a child that appears to be well nourished may be deficient in Vitamin A if adequate amounts of the vitamin are not provided in his/her diet.

  Conclusion Top

The prevalence of VAD among Nigerian children appears to have reduced significantly; however, further studies are required to assess the current national prevalence, so as to design programmes that can achieve further reduction in the proportion of children affected.

Limitation of the study

The influence of the Vitamin A content of diets taken by the children on their Vitamin A status was not assessed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Haskell MJ, Islam MA, Handelman GJ, Peerson JM, Jones AD, Wahed MA, et al. Plasma kinetics of an oral dose of [2H4]retinyl acetate in human subjects with estimated low or high total body stores of Vitamin A. Am J Clin Nutr 1998;68:90-5.  Back to cited text no. 13
Oyedeji GA. Socioeconomic and cultural background of hospitalized children in Ilesa. Niger J Paediatr 1985;13:111-8.  Back to cited text no. 14
World Health Organization. WHO Child Growth Standards: Methods and Development. Geneva: World Health Organization; 2006.  Back to cited text no. 15
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Adelekan DA, Fatusi AO, Fakunle JB, Olotu CT, Olukoga IA, Jinadu MK, et al. Prevalence of malnutrition and Vitamin A deficiency in nigerian preschool children subsisting on high intakes of carotenes. Nutr Health 1997;12:17-24.  Back to cited text no. 17
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Akinyinka OO, Usen SO, Akanni A, Falade AG, Osinusi K, Ajaiyeoba IA, et al. Vitamin A status of pre-school children in Ibadan (South West Nigeria), risk factors and comparison of methods of diagnosis. West Afr J Med 2001;20:243-8.  Back to cited text no. 19
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Uzoechina ON, Okoro BA. Serum Vitamin A levels of pre-school children in a Nigerian rural community. Ann Trop Paediatr 1994;14:157-61.  Back to cited text no. 21
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Maziya-Dixon BB, Akinyele IO, Sanusi RA, Oguntona TE, Nokoe SK, Harris EW, et al. Vitamin A deficiency is prevalent in children less than 5 y of age in Nigeria. J Nutr 2006;136:2255-61.  Back to cited text no. 23
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