- Vitamin A deficiency is a significant public health concern, particularly in developing countries, where it is a leading cause of preventable blindness in children and contributes to increased morbidity and mortality from infections.
- Vitamin A, a fat-soluble vitamin, plays a vital role in vision, immune function, epithelial cell integrity, growth, and reproduction. It exists in two main forms: preformed vitamin A (retinol and retinyl esters, found in animal sources like liver, dairy, and fish) and provitamin A carotenoids (such as beta-carotene, found in orange and green leafy vegetables), which the body converts into active vitamin A.
- The most well-known and early sign of vitamin A deficiency is night blindness (nyctalopia)—difficulty seeing in low-light conditions—due to impaired production of rhodopsin, a visual pigment in the retina. If the deficiency persists, it can progress to more serious ocular manifestations, collectively known as xerophthalmia, which includes conjunctival and corneal dryness, Bitot’s spots (foamy accumulations on the conjunctiva), and eventually corneal ulceration and keratomalacia, a softening of the cornea that can lead to irreversible blindness.
- Beyond the eyes, vitamin A is essential for maintaining the integrity of mucous membranes in the respiratory, gastrointestinal, and genitourinary tracts. Deficiency weakens these barriers and impairs immune responses, increasing susceptibility to infections, especially measles, pneumonia, and diarrhea in children. In fact, vitamin A deficiency is associated with higher child mortality rates, and supplementation has been shown to significantly reduce deaths in high-risk populations. In adults, deficiency may present as dry skin, poor wound healing, and reproductive issues.
- Vitamin A deficiency arises from inadequate dietary intake, especially in populations with limited access to animal-based foods or vitamin A-rich produce. It is often exacerbated by malabsorption disorders (such as celiac disease, Crohn’s disease, or chronic diarrhea), fat malabsorption, or liver disorders that impair storage and metabolism of the vitamin. Infants and young children, pregnant and lactating women, and individuals with chronic illness are at particular risk.
- Diagnosis is primarily clinical, based on history and signs such as night blindness and xerophthalmia, but can be confirmed by low serum retinol levels. However, these levels may be affected by infection and inflammation. In severe cases, eye examination may reveal classic features of advanced ocular disease.
- Treatment involves high-dose vitamin A supplementation, particularly in children with deficiency symptoms or in areas with endemic deficiency. The World Health Organization (WHO) recommends large, periodic doses for children under five years of age in high-risk regions. For individuals with malabsorption, parenteral (injectable) vitamin A may be necessary. Prevention strategies include promoting breastfeeding, dietary diversification, food fortification, and public health education. In many countries, staple foods such as cooking oil, sugar, or flour are fortified with vitamin A to combat deficiency.
