Vitamin A is a generic term for a large number of related compounds. Retinol (an alcohol) and retinal (an aldehyde) are often referred to as preformed vitamin A. Retinal can be converted by the body to retinoic acid, the form of vitamin A known to affect gene transcription. Retinol, retinal, retinoic acid, and related compounds are known as retinoids. Beta-carotene and other carotenoids that can be converted by the body into retinol are referred to as provitamin A carotenoids. Hundreds of different carotenoids are synthesised by plants, but only about 10 % of them are provitamin A carotenoids. This book presents important new research in the field.Loessing, Ingrid T. is the author of 'Vitamin A New Research', published 2007 under ISBN 9781600216688 and ISBN 1600216684.