Subclinical vitamin A deficiency: a potentially unrecognized problem in the United States
Vitamin A deficiency in its subclinical form is a world health problem in young children. The problem is probably under recognized in the United States and other developed countries who do not normally consider their citizens to be malnourished. Lack of a simple screening test to measure subclinical deficiency adds to this problem. Consequently, focused dietary assessment of vitamin A intake by a Food Frequency Questionnaire (FFQ) is a necessary component of health care maintenance, especially for toddlers and preschool age children. Dietary counseling and vitamin supplementation for high risk children is a necessary health promotion intervention.
Vitamin A deficiency is one of the world's top five major malnutrition problems estimated to affect more than 124 million children worldwide (Fuchs, Ausayakhum, Ruckphaopunt, Tansuhaj, & Suskind, 1994; Rumore, 1993; Underwood & Olson, 1993). Vitamin A deficiency is known to occur in developing countries, most commonly in children under 5 years of age (Rumore, 1993; Humphrey, West, & Sommer, 1992; West, et al., 1988). Vitamin A deficiency has long been identified as the leading cause of pediatric blindness in the world (Solon, 1986; Sommer, 1982; West, Howard & Sommer, 1989), but recently, vitamin A has also been recognized for its importance in promoting overall health and survival of children (Olson, 1993; Ross, 1992; Semba, 1994, Underwood, 1994).
Young children in developed countries, such as the United States, are also susceptible to vitamin A deficiency if their dietary intake of this essential vitamin is inadequate. Children, especially in the toddler and preschool age groups, should be screened for adequate intake of vitamin A rich foods as part of their well child care. A vitamin A food frequency questionnaire and risk assessment tool has been developed for clinical practice and target populations in the United States at highest risk for subclinical vitamin A deficiency identified by history or clinical findings.
The Role of Vitamin A in Health and Illness
Vitamin A is essential for maintaining the integrity of the epithelial tissues, particularly the surface linings of the eye, respiratory, urinary, and intestinal tracts-areas where most bacteria enter the body (Olson, 1993; Ross, 1992; Sommer, 1982). Due to the eye's sensitivity, the first clinically apparent warning signs of vitamin A deficiency are dry conjunctive (xerophthalmia) and an inability to see in dim light (night blindness) (Maberly, Trowbridge, Yip, Sullivan, West, 1994; Sommer, 1994). Although the number of children clinically affected has declined over the last decade, these children represent only a fraction of those whose health and survival is compromised by an inadequate vitamin A status (Bates, 1993; World Health organization, 1992). Worldwide, the World Health organization (WHO) estimates 70 to 80 million more children are subclinically vitamin A deficient.
Vitamin A deficiency, in subclinical forms, increases children's susceptibility to infection, reduces physical growth, and decreases the possibility of survival from serious illness (Sommer, 1994; Underwood, 1994). Recent epidemiologic studies in developing countries have identified a relationship between subclinical vitamin A deficiency and higher rates of morbidity and mortality from common infectious diseases such as...
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