Circulating endogenous retinoic acid concentrations among participants enrolled in a randomized placebo-controlled clinical trial of retinyl palmitate.

Author: Sedjo RL, Ranger-Moore J, Foote J, Craft NE, Alberts DS, Xu MJ, Giuliano AR

Author affiliation: H. Lee Moffitt Cancer Center & Research Inst., MRC 2 East Room 2067, 12902 Magnolia Drive, Tampa, FL 33612-9497, USA.

Publication date & source: 2004.11, Cancer Epidemiol Biomarkers Prev., 13(11 Pt 1):1687-92.

Retinoids have been studied extensively for their chemopreventive properties. The biological activity of retinoids is acquired through their conversion to retinoic acid (RA). Characterization of endogenous circulating RA concentrations after supplementation with vitamin A over longer time periods has not been done previously. Our investigation was conducted to determine whether vitamin A (retinyl palmitate) supplementation significantly increases circulating RA concentrations of all-trans-, 9-cis-, and 13-cis-RA. Using plasma samples from 41 participants enrolled in a randomized clinical trial of placebo, 25,000, 50,000, or 75,000 IU supplemental retinyl palmitate daily, high-performance liquid chromatography analyses were conducted for concentrations of three RA isomers. Seven plasma samples were analyzed for each participant over a 16-month period. Based on an intention-to-treat analysis, results obtained using linear mixed models showed that supplementation with retinyl palmitate statistically significantly increased concentrations of all three RA isomers from baseline levels. This study suggests that supplementation with retinyl palmitate is an effective means to increase circulating all-trans, 9-cis-, and 13-cis-RA concentrations among humans.

Indexes of Skin Care Research Abstracts by Subject Category Most Recent

Web SmartSkinCare.com

Home | About Us | Contact Us | Ask a Question | Resources

Copyright © 1999-2009 by Dr. G. Todorov / SmartSkinCare.com
Site Disclaimer | Copyright Certification