title: Bioavailability in humans of zinc from beef: intrinsic vs extrinsic labels.
abstract: Beef is a concentrated source of zinc. However, the bioavailability of Zn from beef has not been clearly established. It is also unclear whether there is a difference in absorption between intrinsic and extrinsic Zn. To address these questions, a calf was labeled with 65ZnCl2 and the meat was used as a source of intrinsically labeled beef. Twelve subjects were given a meal containing 100 g beef labeled either intrinsically or extrinsically with 65ZnCl2. Gamma-ray emissions, as determined by whole-body counting, were used to calculate Zn absorption. Absorption values were 20.9 +/- 5.5% from the extrinsic meal and 26.4 +/- 10.6% from the intrinsic meal, a difference that was not statistically significant (p greater than 0.05). Zn absorption was thus much less than the 40% assumed in establishing the 1980 Recommended Dietary Allowance for Zn. These results also indicate that extrinsic labels of Zn are valid markers of zinc absorption in beef.
authors.affiliation: Department of Food and Nutrition, North Dakota State University, Fargo 58105.
authors.forename: D D
authors.initials: DD
authors.lastname: Gallaher
authors.forename: P E
authors.initials: PE
authors.lastname: Johnson
authors.forename: J R
authors.initials: JR
authors.lastname: Hunt
authors.forename: G I
authors.initials: GI
authors.lastname: Lykken
authors.forename: M J
authors.initials: MJ
authors.lastname: Marchello
mesh_terms: D000328:Adult; D000818:Animals; D001682:Biological Availability; D002417:Cattle; D005260:Female; D006801:Humans; D008297:Male; D008460:Meat / Q000032:analysis*; D015032:Zinc / Q000032:analysis / Q000378:metabolism*
chemical_list: D015032:Zinc