| Facts About Vitamin A and Carotenoids | |
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When can vitamin A deficiency occur?
Vitamin A deficiency rarely occurs in the United States, but it is still a major public health problem in the developing world. It is most often associated with protein/calorie malnutrition and affects over 120 million children worldwide (8). It is also a leading cause of childhood blindness. In countries where immunization programs are not widespread and vitamin A deficiency is common, millions of children die each year from complications of infectious diseases such as measles. (8).
Signs of vitamin A deficiency
Signs of vitamin A deficiency include night blindness, dry skin, and decreased resistance to infections. In ancient Egypt it was known that night blindness could be cured after eating liver, which was later found to be a rich source of vitamin A (1). Vitamin A deficiency contributes to blindness by making the eye very dry, damaging the cornea of the eye (referred to as xerophthalmia), and promoting damage to the retina of the eye (24). Extremely dry skin, dry hair, sloughing off of skin, and broken fingernails are other common signs of vitamin A deficiency.
Vitamin A deficiency also decreases resistance to infections (1, 10). When there is not enough vitamin A, cells lining the lung lose their ability to remove disease-causing microorganisms. This may contribute to the pneumonia associated with vitamin A deficiency (9).
There is increased interest in subclinical forms of vitamin A deficiency, described as low storage levels of vitamin A that do not cause overt deficiency symptoms. This mild degree of vitamin A deficiency may increase children's risk of developing respiratory and diarrheal infections, decrease growth rate, slow bone development, and decrease likelihood of survival from serious illness (8, 25, 26).
Children living in the United States who are considered to be at increased risk for subclinical vitamin A deficiency include:
- toddlers and preschool age children
- children living at or below the poverty level
- children with inadequate health care or immunizations
- children living in areas with known nutritional deficiencies
- recent immigrants or refugees from developing countries with high incidence of vitamin A deficiency or measles, and
- children with diseases of the pancreas, liver, intestines, or with inadequate fat digestion/absorption (8).
As a result of the worldwide significance of vitamin A deficiency in children, the World Health Organization (WHO) and the United Nations International Children's Emergency Fund (UNICEF) issued joint statements about vitamin A and children's health. Both agencies recommend vitamin A administration for all children diagnosed with measles in communities where vitamin A deficiency is a serious problem and where death from measles is greater than 1%. In 1994, the American Academy of Pediatrics recommended vitamin A supplementation for children 6 to 24 months of age hospitalized with measles and for hospitalized children older than 6 months who are considered to be at high-risk for subclinical vitamin A deficiency (27).
Next page > Who needs vitamin A supplements and is there a risk with too much? > Page 1, 2, 3, 4, 5, 6
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