Document Detail

Factors influencing the measurement of bioavailability, taking calcium as a model.
MedLine Citation:
PMID:  11285351     Owner:  NLM     Status:  MEDLINE    
For non-metabolizable supplemental nutrients, bioavailability is effectively equivalent to absorbability. Methods for measuring absorbability (balance, pharmacokinetic, tracer, urine increment, evoked physiological responses, and in vitro) are briefly characterized and their utility compared. When intrinsic labeling of a source is possible, tracer methods are generally the most accurate and precise, as well as often the least expensive. Factors influencing the measured end points of the various methods are described briefly. These include source factors such as pharmaceutic formulation, subject factors such as mucosal mass and the need status of the absorbing subject, and co-ingested factors such as other foods or food constituents. Extensive experience has shown that absorbability is difficult to predict from knowledge of the chemistry of the source, or even from the results of in vitro testing. Hence direct measurement of absorbability is essential to assure regulators and the general public that the source delivers what it promises.
R P Heaney
Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  The Journal of nutrition     Volume:  131     ISSN:  0022-3166     ISO Abbreviation:  J. Nutr.     Publication Date:  2001 Apr 
Date Detail:
Created Date:  2001-04-04     Completed Date:  2001-05-10     Revised Date:  2005-11-16    
Medline Journal Info:
Nlm Unique ID:  0404243     Medline TA:  J Nutr     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1344S-8S     Citation Subset:  IM    
Creighton University, Osteoporosis Research Center, Omaha, NE 68131, USA.
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MeSH Terms
Biological Availability*
Blood / metabolism
Calcium / pharmacokinetics
Radioactive Tracers
Urine / chemistry
Reg. No./Substance:
0/Radioactive Tracers; 7440-70-2/Calcium

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