Vitamin A deficiency

Introduction

What is Vitamin A Deficiency?

Vitamin A deficiency is a surprisingly major health problem worldwide. It is most prevalent in children and expectant women. It is the world leading cause of preventable blindness in children. It compromises immunity and increases the risk of disease and death from severe infections. It is a significant contributor to maternal and child mortality.

According to the World Health Organisation, an estimated 250 million preschool children are Vitamin A deficient and it is likely that in Vitamin A-deficient areas a substantial proportion of pregnant women are Vitamin A-deficient. An estimated 250,000 to 500,000 Vitamin A-deficient children become blind every year, half of them dying within 12 months of losing their sight

For children, lack of Vitamin A causes severe visual impairment and blindness, and significantly increases the risk of severe illness, and even death, from such common childhood infections as diarrhoeal disease and measles. 

For pregnant women in high-risk areas, Vitamin A deficiency occurs especially during the last trimester when demand by both the unborn child and the mother is highest. The mother's deficiency is demonstrated by the high prevalence of night blindness during this period. The impact of Vitamin A deficiency on mother-to-child HIV transmission needs further investigation

Vitamin A has two functions in the body:

• In the eye to allow for night-vision or for seeing in dim-light circumstances.
• In the body for regulating the development of various tissues, such as the cells of the skin, and the lining of the lungs and intestines. Vitamin A is important during embryological development, since without the fertilized egg cannot develop into a foetus. 

Overall, it is crucial for a healthy immune system.

Causes of Vitamin A deficiency

• Primary Vitamin A deficiency is usually caused by prolonged dietary deprivation. 
• Secondary Vitamin A deficiency tends to happen in:
  • alcoholics
  • people with chronic liver conditions such cirrhosis 
  • people with diseases that affect the intestine's ability to absorb fat. Examples of such diseases are chronic diarrhoea, celiac disease (chronic nutritional disorder), cystic fibrosis, and cholestasis (bile-flow failure or interference). 
  • It may also occur after intestinal surgery. 
  • Vitamin A deficiency is common in prolonged protein-energy malnutrition not only because the diet is deficient but also because Vitamin A storage and transport is defective. 

Symptoms of Vitamin A deficiency

• Eye symptoms
• Rough, dry skin 
• Growth retardation in children 
• Vulnerability to infections such as urinary tract and respiratory infections 

Night blindness: This is the earliest symptom of Vitamin A deficiency. It is the result of difficulty for the eyes to adjust to dim light. Affected individuals are unable to distinguish images in low levels of illumination. People with night blindness have poor vision in dim light or/darkness, but see normally when adequate light is present.

When to see a doctor

Prevention and treatment

Prevention and Treatment

• Eat diet rich in Vitamin A. Liver is the richest animal source. In plants it is in the form of carotenoids like beta-carotene, best found in yellow and dark green crops. (see table).
• Food fortification: can be done with wheat, milk or even sugar but this is a costly process. Margarine and oil are the ideal food vehicles for Vitamin A fortification. 
• Supplements: this is the approach taken by most developing countries. Some have incorporated Vitamin A supplementation to their immunization schedule. Giving the supplements up to five years of life. It is usually given in oral form. It is affordable and readily acceptable amongst most communities. 

Remember a Vitamin A deficiency in lactating mothers will produce breast milk with low levels of Vitamin A. Maternal supplementation benefits both mother and breast-fed infant: high dose Vitamin A supplementation of the breast-feeding mother in the first month after delivery can provide the breast-fed infant with an appropriate amount of Vitamin A through breast milk. However, high-dose supplementation of pregnant women should be avoided because it can cause miscarriage and birth defects. 

How much Vitamin A do you need?

Recommended Dietary Allowance (RDA) for Vitamin A as Preformed Vitamin A (Retinol Activity Equivalents) 

Vitamin A rich foods

Treatment

The treatment for Vitamin A Deficiency related problems involves giving high dose Vitamin A (usually available as retinyl palmitate) either orally or through injection.

In children with complicated measles, Vitamin A can shorten the duration of the disorder and reduce the severity of symptoms and risk of death.

Prognosis

The prognosis for correcting night blindness is excellent. 

Xerophthalamia can be corrected with Vitamin A therapy. Ulcerations, tissue death, and total blindness, caused by severe Vitamin A deficiency, cannot be treated with Vitamin A.

Review Process

1: First edition: Dr. Mukuhi Nganga, 2009
2: Review and update: Alice Ndong February 2012

Information Source Links

• Human Vitamins requirement; Report of Joint FAO - WHO expert Consultation 2002 ( Bangkok Thailand)
• Balch Phylis A. and and Balch James F.; Prescription fro Nutritional healing, 3^rd Edition.
• Lee V, Ahmed F, Wada S, et al. (2008): Extent of vitamin A deficiency among rural pregnant women in Bangladesh. PUBLIC HEALTH NUTR. Jun 12 2008;1-6.
• D'Souza RM, D'Souza R (2002):. Vitamin A for treating measles in children. COCHRANE DATABASE SYST REV;(1):CD001479.