title: Vitamin A and infancy. Biochemical, functional, and clinical aspects.
abstract: Vitamin A is a very intriguing natural compound. The molecule not only has a complex array of physiological functions, but also represents the precursor of promising and powerful new pharmacological agents. Although several aspects of human retinol metabolism, including absorption and tissue delivery, have been clarified, the type and amounts of vitamin A derivatives that are intracellularly produced remain quite elusive. In addition, their precise function and targets still need to be identified. Retinoic acids, undoubtedly, play a major role in explaining activities of retinol, but, recently, a large number of physiological functions have been attributed to different retinoids and to vitamin A itself. One of the primary roles this vitamin plays is in embryogenesis. Almost all steps in organogenesis are controlled by retinoic acids, thus suggesting that retinol is necessary for proper development of embryonic tissues. These considerations point to the dramatic importance of a sufficient intake of vitamin A and explain the consequences if intake of retinol is deficient. However, hypervitaminosis A also has a number of remarkable negative consequences, which, in same cases, could be fatal. Thus, the use of large doses of retinol in the treatment of some human diseases and the use of megavitamin therapy for certain chronic disorders as well as the growing tendency toward vitamin faddism should alert physicians to the possibility of vitamin overdose.
authors.affiliation: Department of Pediatric, Medical School, Second University of Naples, Naples, Italy.
authors.forename: Silverio
authors.initials: S
authors.lastname: Perrotta
authors.forename: Bruno
authors.initials: B
authors.lastname: Nobili
authors.forename: Francesca
authors.initials: F
authors.lastname: Rossi
authors.forename: Daniela
authors.initials: D
authors.lastname: Di Pinto
authors.forename: Valeria
authors.initials: V
authors.lastname: Cucciolla
authors.forename: Adriana
authors.initials: A
authors.lastname: Borriello
authors.forename: Adriana
authors.initials: A
authors.lastname: Oliva
authors.forename: Fulvio
authors.initials: F
authors.lastname: Della Ragione
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002648:Child; D002675:Child, Preschool; D004063:Digestion; D005314:Embryonic and Fetal Development; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007408:Intestinal Absorption; D007774:Lactation; D018673:Nutrition Policy; D009751:Nutritional Requirements; D009752:Nutritional Status; D011247:Pregnancy; D011248:Pregnancy Complications; D014801:Vitamin A / Q000008:administration & dosage / Q000009:adverse effects / Q000502:physiology*; D014802:Vitamin A Deficiency
chemical_list: D014801:Vitamin A