Inclusion of Vitamin A intake data provides improved compartmental model-derived estimates of vitamin a total body stores and disposal rate in older adults

Michael H. Green, Jennifer Lynn Ford, Joanne Balmer Green

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Background: Sampling times and study duration impact estimates of kinetic parameters and variables including total body stores (TBS) and disposal rate (DR) when compartmental analysis is used to analyze vitamin A kinetic data. Objective: We hypothesized that inclusion of dietary intake (DI) of vitamin A as an additional input would improve confidence in predictions of TBS and DR when modeling results appear to indicate that studies are not long enough to accurately define the terminal slope of the plasma retinol isotope response curve. Methods: We reanalyzed previously published data on vitamin A kinetics monitored over 52 d in 7 US and 6 Chinese adults (means: 56 y, BMI 26.6 kg/m2, 38% males), adding an estimate for vitamin A intake [2.8 μmol/d (mean RDA)] as an input during application of the Simulation, Analysis and Modeling software. Results: Use of a model with 1 extravascular compartment (1 EV), as in the original analysis, resulted in predictions of vitamin A intake that were higher than physiologically reasonable; inclusion of intake data in a model with 2 extravascular compartments (2 EV DI) resulted in more realistic estimates of intake and DR. Specifically, predictions of DR by the 2 EV DI (versus 1 EV) model were 2.10 compared with 12.2 μmol/d (US) and 2.21 compared with 5.13 μmol/d (Chinese). Predictions of both TBS [2056 compared with 783 μmol (US) and 594 compared with 219 μmol (Chinese)] and days of vitamin A stores [981 compared with 64 d (US) and 269 compared with 43 d (Chinese)] were higher using the new approach. Conclusions: Inclusion of vitamin A intake as additional data input when modeling vitamin A kinetics can compensate for less-than-optimal study duration, providing more realistic predictions of vitamin A TBS and DR. This approach advances the application of compartmental analysis to the study of vitamin A and, potentially, other nutrients.

Original languageEnglish (US)
Pages (from-to)1282-1287
Number of pages6
JournalJournal of Nutrition
Volume149
Issue number7
DOIs
StatePublished - Jan 1 2019

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Vitamin A
Vitamins
Sampling Studies
Time and Motion Studies
Isotopes
Software
Food

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

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title = "Inclusion of Vitamin A intake data provides improved compartmental model-derived estimates of vitamin a total body stores and disposal rate in older adults",
abstract = "Background: Sampling times and study duration impact estimates of kinetic parameters and variables including total body stores (TBS) and disposal rate (DR) when compartmental analysis is used to analyze vitamin A kinetic data. Objective: We hypothesized that inclusion of dietary intake (DI) of vitamin A as an additional input would improve confidence in predictions of TBS and DR when modeling results appear to indicate that studies are not long enough to accurately define the terminal slope of the plasma retinol isotope response curve. Methods: We reanalyzed previously published data on vitamin A kinetics monitored over 52 d in 7 US and 6 Chinese adults (means: 56 y, BMI 26.6 kg/m2, 38{\%} males), adding an estimate for vitamin A intake [2.8 μmol/d (mean RDA)] as an input during application of the Simulation, Analysis and Modeling software. Results: Use of a model with 1 extravascular compartment (1 EV), as in the original analysis, resulted in predictions of vitamin A intake that were higher than physiologically reasonable; inclusion of intake data in a model with 2 extravascular compartments (2 EV DI) resulted in more realistic estimates of intake and DR. Specifically, predictions of DR by the 2 EV DI (versus 1 EV) model were 2.10 compared with 12.2 μmol/d (US) and 2.21 compared with 5.13 μmol/d (Chinese). Predictions of both TBS [2056 compared with 783 μmol (US) and 594 compared with 219 μmol (Chinese)] and days of vitamin A stores [981 compared with 64 d (US) and 269 compared with 43 d (Chinese)] were higher using the new approach. Conclusions: Inclusion of vitamin A intake as additional data input when modeling vitamin A kinetics can compensate for less-than-optimal study duration, providing more realistic predictions of vitamin A TBS and DR. This approach advances the application of compartmental analysis to the study of vitamin A and, potentially, other nutrients.",
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Inclusion of Vitamin A intake data provides improved compartmental model-derived estimates of vitamin a total body stores and disposal rate in older adults. / Green, Michael H.; Ford, Jennifer Lynn; Green, Joanne Balmer.

In: Journal of Nutrition, Vol. 149, No. 7, 01.01.2019, p. 1282-1287.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Ford, Jennifer Lynn

AU - Green, Joanne Balmer

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N2 - Background: Sampling times and study duration impact estimates of kinetic parameters and variables including total body stores (TBS) and disposal rate (DR) when compartmental analysis is used to analyze vitamin A kinetic data. Objective: We hypothesized that inclusion of dietary intake (DI) of vitamin A as an additional input would improve confidence in predictions of TBS and DR when modeling results appear to indicate that studies are not long enough to accurately define the terminal slope of the plasma retinol isotope response curve. Methods: We reanalyzed previously published data on vitamin A kinetics monitored over 52 d in 7 US and 6 Chinese adults (means: 56 y, BMI 26.6 kg/m2, 38% males), adding an estimate for vitamin A intake [2.8 μmol/d (mean RDA)] as an input during application of the Simulation, Analysis and Modeling software. Results: Use of a model with 1 extravascular compartment (1 EV), as in the original analysis, resulted in predictions of vitamin A intake that were higher than physiologically reasonable; inclusion of intake data in a model with 2 extravascular compartments (2 EV DI) resulted in more realistic estimates of intake and DR. Specifically, predictions of DR by the 2 EV DI (versus 1 EV) model were 2.10 compared with 12.2 μmol/d (US) and 2.21 compared with 5.13 μmol/d (Chinese). Predictions of both TBS [2056 compared with 783 μmol (US) and 594 compared with 219 μmol (Chinese)] and days of vitamin A stores [981 compared with 64 d (US) and 269 compared with 43 d (Chinese)] were higher using the new approach. Conclusions: Inclusion of vitamin A intake as additional data input when modeling vitamin A kinetics can compensate for less-than-optimal study duration, providing more realistic predictions of vitamin A TBS and DR. This approach advances the application of compartmental analysis to the study of vitamin A and, potentially, other nutrients.

AB - Background: Sampling times and study duration impact estimates of kinetic parameters and variables including total body stores (TBS) and disposal rate (DR) when compartmental analysis is used to analyze vitamin A kinetic data. Objective: We hypothesized that inclusion of dietary intake (DI) of vitamin A as an additional input would improve confidence in predictions of TBS and DR when modeling results appear to indicate that studies are not long enough to accurately define the terminal slope of the plasma retinol isotope response curve. Methods: We reanalyzed previously published data on vitamin A kinetics monitored over 52 d in 7 US and 6 Chinese adults (means: 56 y, BMI 26.6 kg/m2, 38% males), adding an estimate for vitamin A intake [2.8 μmol/d (mean RDA)] as an input during application of the Simulation, Analysis and Modeling software. Results: Use of a model with 1 extravascular compartment (1 EV), as in the original analysis, resulted in predictions of vitamin A intake that were higher than physiologically reasonable; inclusion of intake data in a model with 2 extravascular compartments (2 EV DI) resulted in more realistic estimates of intake and DR. Specifically, predictions of DR by the 2 EV DI (versus 1 EV) model were 2.10 compared with 12.2 μmol/d (US) and 2.21 compared with 5.13 μmol/d (Chinese). Predictions of both TBS [2056 compared with 783 μmol (US) and 594 compared with 219 μmol (Chinese)] and days of vitamin A stores [981 compared with 64 d (US) and 269 compared with 43 d (Chinese)] were higher using the new approach. Conclusions: Inclusion of vitamin A intake as additional data input when modeling vitamin A kinetics can compensate for less-than-optimal study duration, providing more realistic predictions of vitamin A TBS and DR. This approach advances the application of compartmental analysis to the study of vitamin A and, potentially, other nutrients.

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