Academic journal article Journal of Health Population and Nutrition

Prevalence of Vitamin A Deficiency in South Asia: Causes, Outcomes, and Possible Remedies

Academic journal article Journal of Health Population and Nutrition

Prevalence of Vitamin A Deficiency in South Asia: Causes, Outcomes, and Possible Remedies

Article excerpt

INTRODUCTION

South Asia constitutes one-fifth of the world's population, and many of the nations have been severely affected by malnutrition. Vitamin A deficiency (VAD) has been established as a major determinant to deleteriously impact the health and economic status of populations in the lower-income South Asian countries, and it exists in poorer settings with economic deprivation. VAD is generally associated with decreased dietary intake of preformed vitamin A and its precursors, together with a high prevalence of infectious diseases, like measles, diarrhoea, and respiratory tract infections. Diets containing insufficient vitamin A lead to decreased serum vitamin A levels, resulting in various physiological implications, especially tissue development, metabolism, and resistance to infections. Severe VAD leads to xerophthalmia, the most common cause of preventable blindness among children (1,2).

Retinol (preformed vitamin A) exists in animal tissues, particularly liver and liver oil (cod liver oil), dairy products, and eggs; [beta]-carotene and its precursor are derived from plant-based foods. Economic and sociocultural determinants lead the world community to rely on plant sources for meeting vitamin A requirements in the form of pro-vitamin, [beta]-carotene, which is subsequently converted into retinol in the gut (3), and its activity is expressed in retinol activity equivalents (RAE): (1 RAE=1 [micro]g retinol, 12 [micro]g p-carotene).

Nearly 44-50% preschool children in South Asian regions were affected by severe VAD (2). Mortality owing to malnutrition and higher prevalence of VAD among neonates and children below 5 years of age in Bangladesh and India constituted one-third of the global mortality rate. Other estimates showed 1.02 billion people to be severely affected by micronutrient deficiencies globally, with vitamin A to be the most deficient nutrient in the body (4,5). Similar studies indicated that 85% of the total South Asian children with xerophthalmia reside in India (2). A significant increase in the magnitude of VAD among Indian women from 2001(5.9%) to 2011 (30.3%) was observed (6).

A study among pregnant women in five districts of Sri Lanka during 1988-1989 showed that 1.0% and 1.2% of women had night blindness and Bitot's spots respectively while 8.1% had low serum vitamin A (<20 [micro]g/dL) during early pregnancy (7). Women (10%-15%) were also observed to be night blind during their third month of pregnancy. Approximately 31% children endured visual loss associated with childhood factors, over 75% of which was attributed to VAD (8). In fact, most children (>90%) who go blind from vitamin A deficiency die; so, they are not even counted in surveys of the prevalence of childhood blindness. Almost 5.7 million children below 5 years of age were identified as vitamin A-deficient in Pakistan (2). Increased risk of blindness was assessed in North West Frontier Province of Pakistan (NWFP) among children aged 6 years or less (9,10), and 16% of the anaemic children in primary schools in Karachi, Pakistan, were shown to be vitamin A-deficient. The risk of VAD in Pakistan is around 70% in pregnant and lactating mothers (11-14).

Lower vitamin A levels were reported in the breastmilk of mothers with VAD; therefore, nursing mothers with VAD transferred relatively lower concentration of vitamin A to the infants through breastfeeding. Pregnant women with VAD generally restrict supply of normal amount of retinol to foetus in late pregnancy (15,16). Malnutrition among under-five children is estimated to be 41% in Bangladesh. Many programmes, like vitamin A supplementation, to eliminate VAD in Bangladesh showed promise but the impact may take time to cover the entire population (17).

Aetiology of vitamin A deficiency

Vitamin A is essentially required in the body to maintain visual system, sustain normal cellular differentiation, develop resistance against infections, and uphold epithelial integrity, red blood cell production, and reproduction. …

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