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

Rebecca L. Sedjo, James Ranger-Moore, Janet A Foote, Neal E. Craft, David S Alberts, Min Jian Xu, Anna R. Giuliano

Research output: Contribution to journalArticle

20 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1687-1692
Number of pages6
JournalCancer Epidemiology Biomarkers and Prevention
Issue number11
Publication statusPublished - Nov 2004


ASJC Scopus subject areas

  • Epidemiology
  • Oncology

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