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Independent effects of Zn intake and Zn status on fractional zinc absorption (FZA) in adult men
Author(s) -
Chung Carolyn Sue,
Dare D,
Peerson J M,
King J C,
Brown K H
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a628-c
Subject(s) - zinc , zoology , dosing , urine , chemistry , medicine , oral administration , endocrinology , biology , organic chemistry
The DRI assumes FZA to be constant when estimating dietary Zn needs, regardless of Zn intake or status. We assessed the independent effects of Zn intake and status on FZA in adult men. Nine men (aged 28–50 yrs, BMI 21–26, usual dietary Zn intake >11 mg/d) were studied 3 times: 1) at baseline; 2) after 1 wk on a liquid diet of 0.6 mg Zn/d and 5 wks on a low Zn diet (LoZ, 4 mg Zn/d); and 3) after 4 wks on an adequate zinc diet (AdZ, 11 mg Zn/d) with supplemental Zn (20 mg/d) given for the first 7d. At the end of each period, subjects consumed a day of 3 AdZ test meals with oral tracers of 67 Zn (total 1.1 mg 67 Zn/d) followed by a day of 3 LoZ test meals with oral tracers of 70 Zn (total 0.4 mg 70 Zn/d) or vice versa, depending on diet period. Five days after oral dosing, 0.5 mg 70 Zn was given IV. Urine collected d 3–5 and d 8–10 after oral dosing was analyzed by ICPMS for 67:66 and 70:66 Zn ratios. FZA was estimated using a modified dual isotope tracer ratio method. Mean FZA was greater from LoZ meals than from AdZ meals (61 ± 14 % vs 36 ± 9 %, p<0.0001), regardless of diet period. Mean combined FZA of test meals decreased from the LoZ to the final AdZ period (53 ± 20 % vs 44 8 ± 16 %, p= 0.04). Plasma Zn concentration did not change by diet period. In summary, current Zn intake markedly affects FZA and is independent of smaller changes in FZA due to chronic zinc intake. Supported by NCBA and GCRC at SFGH, NCRR, NIH (grant MO1‐RR00083‐43).