Vitamin A is essential for eye health and the proper functioning of the immune system. It is found in foods such as milk, liver, eggs, red and orange fruits, red palm oil and green leafy vegetables, although the amount of vitamin A readily available to the body from these sources varies widely. In developing areas of the world, where vitamin A is largely consumed in the form of fruits and vegetables, daily per capita intake is often insufficient to meet dietary requirements. Inadequate intakes are further compromised by increased requirements for the vitamin as children grow or during periods of illness, as well as increased losses during common childhood infections. As a result, vitamin A deficiency is quite prevalent in the developing world and particularly in countries with the highest burden of under-five deaths.
While most people know that vitamin A deficiency (VAD) can lead to blindness – it is in fact the leading cause of preventable childhood blindness – many are unaware that even before blindness occurs, vitamin A-deficient children face a 23 per cent greater risk of dying from ailments such as measles, diarrhoea or malaria. Although many countries have not been able to assess the true level of deficiency because of technical and financial constraints, the World Health Organization (WHO) indicates that, vitamin A deficiency still remains a significant public health problem at the global level. An estimated 33 per cent (190 million) of preschool-age children and 15 per cent (19 million) pregnant women do not have enough vitamin A in their daily diet, and can be classified as vitamin A deficient. Furthermore, another 5.2 million preschool-age suffer from clinical VAD. The highest prevalence and numbers are found among countries of sub-Saharan Africa and South East Asia where more than 40 per cent of preschool-age children are estimated to be vitamin A deficient. Recent WHO estimates indicate that vitamin A deficiency is a clinical problem in 45 countries, and a sub-clinical problem in 122 countries. The map below illustrates the global prevalence of vitamin A deficiency. More information on the prevalence of vitamin A deficiency is available from the World Health Organization's Micronutrient Deficiency Information System.
Global prevalence of vitamin A deficiency
Countries and areas with survey data and regression-based estimates: Preschool-age children
Source: WHO, Global Prevalence of Vitamin A Deficiency in Populations at Risk, 2009.
The 1990 World Summit for Children set the goal of virtual elimination of vitamin A deficiency and its consequences, including blindness, by the year 2000. This goal was also endorsed at the Policy Conference on Ending Hidden Hunger in 1991 and the 1992 International Conference on Nutrition and the UN General Assembly's Special Session on Children in 2002. The critical role of vitamin A for child health and immune function also makes control of deficiency a primary component of child survival efforts, and therefore critical to the achievement of Millennium Development Goal 4: to reduce child mortality, with a two-thirds reduction in under-five mortality by the year 2015.
Programmes to prevent and control vitamin A deficiency enhance a child's chances of survival, reduce the severity of childhood illnesses, ease the strain on health systems and hospitals, and contribute to the well-being of children, their families and communities. Three major deficiency control strategies currently exist, all meant to complement ongoing public health measures for the prevention and control of infectious diseases.
In view of the challenges to rapid and large-scale implementation of food-based interventions, supplementation is currently the primary strategy to control vitamin A deficiency and among the key interventions for improving the survival of young children. Countries carrying out two annual rounds of vitamin A supplementation reaching at least 80 per cent coverage among children 6–59 months (considered "effective coverage") are on track to meet international development goals. Concurrently, efforts will be needed in order to achieve equitable coverage by ensuring that the remaining 20 per cent and at-risk populations within countries are fully protected. Coverage at this threshold will ensure the full child survival benefit of vitamin A supplementation, which will be critical to attaining Millennium Development Goal 4. While guidelines do not yet exist for the phase-out of supplementation, it is expected that priority countries will need to continue vitamin A supplementation at effective coverage levels for the foreseeable future in order to realize international goals for child survival and vitamin A–deficiency control while improving dietary approaches and infectious disease control.
WHO, Global Prevalence of Vitamin A Deficiency in Populations at Risk: WHO global database on vitamin A deficiency, WHO, Geneva, 2009.