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Model to estimate labeled vitamin B12 in eggs for studies of food‐bound B12 absorption
Author(s) -
Johnson Heidi,
Garrod Marge,
Allen Lindsay
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.865.1
Subject(s) - vitamin b12 , excretion , absorption (acoustics) , chemistry , zoology , feces , cyanocobalamin , metabolism , kinetics , biochemistry , biology , ecology , physics , quantum mechanics , acoustics
About 25% of elderly in the US have impaired absorption for vitamin B12 from food. Study of this condition has been limited by lack of food that contain intrinsically labeled B12. Supplementation of laying hens with B12 increases B12 in eggs (Naber, 1993). However, relationships between B12 dose, transfer rates between tissues and B12 uptake into egg is unknown. To estimate vitamin B12 kinetics and transfer into eggs in a laying hen, a computer model of B12 metabolism was created based on experimental data from Denton et al. (1954) and Edwards (1967) representing 6 dose‐response treatments. The model has 5 state variables representing B12 in blood, gut, muscle, other tissues and eggs. Exchanges between state variables are based on mass action kinetics. Despite different experimental protocols and dosing schemes, predicted exchange rates of B12 between tissues were remarkably similar with fecal excretion 0.08 %/d, urinary excretion 0.15 %/d, absorption 0.1%/d, exchange between muscle and other tissues with blood 0.5 %/d, and uptake into eggs from 0.03 to 0.2 %/d. Model estimates of total 57 Co B12 absorbed, retained, and in eggs from Edwards (1967), and model estimates of μg B12/egg from Denton et al. (1954) were within 5% of data. Therefore the model can be used to estimate B12 enrichment of eggs using different dosing protocols, for use in human absorption studies.