Vitamin A and lung development.

Several lines of evidence suggest that vitamin A is involved in lung development. They are: 1) Dietary deficiency of the fat-soluble vitamin A results in squamous metaplasia of the tracheal and bronchial epithelium. 2) Infants with vitamin A deficiency have a high incidence of respiratory problems. 3) Levels of two intracellular proteins binding specifically retinol (vitamin A alcohol) and retinoic acid (vitamin A acid) change dramatically during perinatal lung development. 4) Prematurely born infants hospitalized for respiratory problems have low serum concentrations of retinol and retinol-binding protein. 5) Postnatal supply of vitamin A by parenteral alimentation may not be adequate, as large quantities of vitamin A are absorbed by the tubing. Careful assessment of vitamin A status in postnatal nutritional management of premature infants is desirable.