Vitamin A deficiency is a major health problem that affects around one third of children aged under five years. Vitamin A deficiency causes blindness in about 250,000–500,000 children from developing countries every year and the highest prevalence is in Southeast Asia and Africa. According to the Global Alliance for Vitamin A, several strategies should be encouraged to help manage this problem and some of these are described below.
- Breastfeeding should be encouraged as the only form of nourishing the new born.
- Women in the immediate post-partum period are advised to take high-dose supplementation.
- Vitamin a supplementation of children aged under five is encouraged.
- Vitamin A food fortification is being researched but is not currently adopted as an approach to deficiency.
Vitamin A deficiency can be either primary or secondary. Primary deficiency is seen in children and adults who do not consume enough foods rich in Vitamin A such as yellow/orange fruits and vegetables (mangoes, pumpkin) or animal sources such as liver. Babies who are weaned off breast milk too early are also at an increased risk of Vitamin A deficiency.
Secondary vitamin A deficiency occurs as a result of gastrointestinal abnormalities that lead to poor absorption of the vitamin available in food. Vitamin A is a fat-soluble vitamin meaning it is absorbed after it has dissolved in fats. A low-fat diet can therefore hinder the adequate absorption and use of vitamin A. Zinc deficiency may also disrupt the absorption and transport of vitamin A. Other factors related to secondary vitamin A deficiency include the abnormal production and release of bile, chronic exposure to cigarette smoke and chronic alcoholism.
Symptoms of Vitamin A deficiency
Vitamin A deficiency leads to some of the following symptoms
- Impaired vision, particularly in dim light (night blindness)
- A dryness of the eyes referred to as xerophthalmia
- Impaired immunity and susceptibility to infection
- Whitish lumps at the hair follicles due to hypokeratosis
- Squamous metaplasia of the normal epithelium in respiratory passages and the bladder leads to a keratinized and thickened epithelium.
Reviewed by Sally Robertson, BSc