title: Vitamin a: history, current uses, and controversies.
abstract: Vitamin A is required for the proper functioning of many important metabolic and physiologic activities, including vision, gene transcription, the immune system and skin cell differentiation. Both excessive and deficient levels of vitamin A lead to poor functioning of many human systems. The biologically active form, retinoic acid, binds to nuclear receptors that facilitate transcription that ultimately leads to it's physiological effects. Retinoids are derivatives of vitamin A that are medications used to treat acne vulgaris, psoriasis, ichthyosis (and other disorders of keratinization), skin cancer prevention as well as several bone marrow derived neoplasias. Systemic retinoids are teratogenic and have to be prescribed with caution and close oversight. Other potential adverse events are controversial. These include the relationship of retinoid derivatives in sunscreens, their effects on bone mineral density, depression and suicidal ideation and inflammatory bowel disease. These controversies will be discussed in detail.
authors.affiliation: Section of Dermatology, Department of Surgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA. Michael.Shane.Chapman@hitchcock.org
authors.forename: M Shane
authors.initials: MS
authors.lastname: Chapman
mesh_terms: D000152:Acne Vulgaris / Q000139:chemically induced / Q000188:drug therapy; D001842:Bone and Bones / Q000378:metabolism; D002454:Cell Differentiation; D003863:Depression / Q000139:chemically induced; D005260:Female; D006801:Humans; D007057:Ichthyosis / Q000139:chemically induced / Q000188:drug therapy; D015212:Inflammatory Bowel Diseases / Q000139:chemically induced; D008297:Male; D018673:Nutrition Policy; D011565:Psoriasis / Q000139:chemically induced / Q000188:drug therapy; D012176:Retinoids / Q000009:adverse effects / Q000378:metabolism / Q000627:therapeutic use; D012737:Sex Factors; D012867:Skin / Q000378:metabolism; D059020:Suicidal Ideation; D013473:Sunscreening Agents / Q000009:adverse effects; D014212:Tretinoin / Q000008:administration & dosage / Q000009:adverse effects; D014801:Vitamin A / Q000008:administration & dosage / Q000378:metabolism / Q000502:physiology*; D014815:Vitamins / Q000008:administration & dosage
chemical_list: D012176:Retinoids; D013473:Sunscreening Agents; D014815:Vitamins; D014801:Vitamin A; D014212:Tretinoin