A retinol isotope dilution equation predicts both group and individual total body vitamin A stores in adults based on data from an early postdosing blood sample

Michael H. Green, Jennifer Lynn Ford, Joanne Balmer Green, Philip Berry, Alan V. Boddy, Anthony Oxley, Georg Lietz

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Background: Retinol isotope dilution (RID) is used to determine vitamin A total body stores (TBS) after an oral dose of a vitamin A stable isotope. The generally accepted prediction equation proposed by Olson's group in 1989 (Furr et al. Am J Clin Nutr 1989;49:713-6) includes factors related to dose absorption and retention, isotope equilibration in plasma compared with stores, catabolism during the mixing period, and the optimal time for measuring plasma isotope enrichment. Objectives: The objectives were 1) to develop a modified RID equation and identify an earlier sampling time for predicting TBS and 2) to improve prediction in individuals as well as groups. Methods: To develop amodifiedRIDequation, weused results ofmodel-based compartmental analysis [the Simulation, Analysis and Modeling software (WinSAAMversion 3.0.8; http://www. WinSAAM.org)] of plasma [13C10]retinol kinetic data from32 previously studied, healthy young adults of European ancestry who hadmoderate vitamin A intakes and who ingested 2.95mmol [13C10]retinyl acetate. Results: We examined the time dependence of factors in the prediction equation related to absorption/retention (Fa) and isotope equilibration (S) and determined that 4 or 5 d postdosing was the optimal sampling time. TBS calculated by the equation TBS = Fa x S x (1/SAp), where SAp is plasma retinol specific activity (fraction of dose/μmol), were highly correlated with model-predicted TBS (r = 0.95 and 0.96 for 4 and 5 d, respectively; P < 0.001); predictions for individuals were also highly correlated (Rs = 0.94 and 0.94; P < 0.001). Conclusion: The equation TBS ≈ 0.5 3 (1/SAp) accurately predicted vitamin A TBS in this group of 32 healthy young adults and its individualmembers with the use of data from 1 blood sample taken 4 d after isotope administration.

Original languageEnglish (US)
Pages (from-to)2137-2142
Number of pages6
JournalJournal of Nutrition
Volume146
Issue number10
DOIs
StatePublished - 2016

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Fingerprint Dive into the research topics of 'A retinol isotope dilution equation predicts both group and individual total body vitamin A stores in adults based on data from an early postdosing blood sample'. Together they form a unique fingerprint.

Cite this