Zinc (Zn) absorption: Comparison of extrinsic label with intrinsic Zn in test meals.

BACKGROUND: Extrinsic labeling techniques for determining fractional absorption of Zn (FAZ) have never been adequately evaluated. OBJECTIVE: The objective of this study, part of a larger project, was to compare results for determination of FAZ_extrinsic from a variety of different total diets using our own extrinsic labeling technique with results for simultaneous determination of FAZ_intrinsic. DESIGN: FAZ was determined for 5 days in 23 adults (Female) while consuming a constant rotating diet based on habitual intake. Zn intake ranged from 5-33mg/d, median 7.6mg/d. For extrinsic labeling, ⁷⁰Zn tracer was administered gradually during the second half of each meal and absorption determined by our dual isotope tracer ratio (DITR) technique (⁶⁷Zn infused IV) and by fecal monitoring (FM). FmZ_intrinsic was calculated from the sum of net absorption of Zn and intestinal excretion of endogenous Zn. RESULTS: Mean ± SD FAZ by DITR, FM and intrinsic were 0.28±0.11, 0.30±0.11 and 0.31±0.15, respectively (ANOVA, p=0.229). CONCLUSION: Small, not statistically significant, differences were found between these 3 methods for determining FAZ. [ABSTRACT FROM AUTHOR]