Biochemistry and Physiological Role

J L Napoli, University of California, Berkeley, CA, USA

© 2005 Elsevier Ltd. All rights reserved.

In 1913, E.V. McCollum isolated a yellow, fat-soluble substance from egg yolks that was critical for animal growth. He called it fat-soluble A, indicating the first isolated of several dietary microconsti-tuents emerging as obligatory for vertebrate life and health. Later, fat-soluble A was renamed vitamin A, derived from the terminology 'vital amine,' coined by Casmir Funk to describe these obligatory micronutrients.

Currently, the term vitamin A refers to the specific organic compound all-trans-retinol (atROH). atROH, however, does not have biological activity in its own right. Rather, it serves as a circulating substrate for metabolism into the compounds that fulfill the biological functions attributed to vitamin A. These metabolites include, but may not be limited to, 11-ds-retinal (11cROH) and all-trans--retinoic acid (atRA). The term 'retinoids' describes all compounds that support vitamin A activity, both naturally occurring and synthetic, including atROH. Figure 1 illustrates the structures of key carotenoids and retinoids.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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