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Volumetric Dilution, Rather Than Sequestration Best Explains the Low Vitamin D Status of Obesity
Author(s) -
Drincic Andjela T.,
Armas Laura A.G.,
Diest Eileen E.,
Heaney Robert P.
Publication year - 2012
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1038/oby.2011.404
Subject(s) - vitamin d and neurology , cholecalciferol , medicine , obesity , vitamin , linear regression , endocrinology , vitamin d deficiency , body weight , body mass index , mathematics , statistics
Vitamin D status is known to be poor in obese individuals; there is no consensus as to the reason. Cross‐sectional study of the relation between serum 25‐hydroxyvitamin D (25(OH)D) concentration and body size in the baseline data from unsupplemented adults entering two study cohorts in our research unit, N = 686. Regression analyses of body size variables against serum 25(OH)D concentration, using both linear and hyperbolic models. The fit to a hyperbolic model of 25(OH)D against body weight completely removed the obesity‐related component of inter‐individual variability in serum 25(OH)D concentration. The hyperbolic fit using total body weight was significantly better than any linear model, and specifically better than any using BMI. Dilution of ingested or cutaneously synthesized vitamin D in the large fat mass of obese patients fully explains their typically low vitamin D status. There is no evidence for sequestration of supplemental or endogenous cholecalciferol. Vitamin D replacement therapy needs to be adjusted for body size if desired serum 25(OH)D concentrations are to be achieved.