QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Heaney, R. P. Search for Related Content PubMed PubMed Citation Articles by Heaney, R. P.

---

Supplement

Factors Influencing the Measurement of Bioavailability, Taking Calcium as a Model¹

Creighton University, Osteoporosis Research Center, Omaha, NE 68131

²To whom correspondence should be addressed. E-mail: rheaney{at}creighton.edu

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.

KEY WORDS: • bioavailiability • absorbability • calcium • pharmaceutics • isotopic tracers • net absorption • gross absorption

This article has been cited by other articles:

				E. A Yetley Multivitamin and multimineral dietary supplements: definitions, characterization, bioavailability, and drug interactions Am. J. Clinical Nutrition, January 1, 2007; 85(1): 269S - 276S. [Abstract] [Full Text] [PDF]

				J. F. Haro, C. Martinez, G. Ros, and M. L. Vidal Note: Stability of Calcium Bioaccessibility and Sensory Parameters During the Storage of Fortified Juices Food Science and Technology International, August 1, 2006; 12(4): 281 - 285. [Abstract] [PDF]

				J. L. Rosado, M. Diaz, A. Rosas, I. Griffit, and O. P. Garcia Calcium Absorption from Corn Tortilla Is Relatively High and Is Dependent upon Calcium Content and Liming in Mexican Women J. Nutr., November 1, 2005; 135(11): 2578 - 2581. [Abstract] [Full Text] [PDF]

				K. H. Thompson and C. Orvig Boon and Bane of Metal Ions in Medicine Science, May 9, 2003; 300(5621): 936 - 939. [Abstract] [Full Text] [PDF]

				S. Herman, I. J Griffin, S. Suwarti, F. Ernawati, D. Permaesih, D. Pambudi, and S. A Abrams Cofortification of iron-fortified flour with zinc sulfate, but not zinc oxide, decreases iron absorption in Indonesian children Am. J. Clinical Nutrition, October 1, 2002; 76(4): 813 - 817. [Abstract] [Full Text] [PDF]