Current dietary zinc intake has a greater effect on fractional zinc absorption than does longer term zinc consumption in healthy adult men.
BACKGROUND
No studies have examined the independent effects of current and longer-term dietary zinc intakes on zinc absorption.


OBJECTIVE
We determined the effects of current compared with longer-term zinc intake on fractional zinc absorption (FZA).


METHODS
We studied 9 men whose usual zinc intakes were >11 mg/d. FZA was measured at baseline, depletion (0.6 mg Zn/d for 1 wk and 4 mg Zn/d for 5 wk), and repletion (11 mg Zn/d for 4 wk with 20 mg supplemental Zn/d for first 7 d). During 2 successive days after each dietary period, subjects consumed either adequate-zinc meals (11 mg Zn/d) with a zinc stable isotope tracer for 1 d, followed by low-zinc meals (4 mg Zn/d) with zinc tracer, or vice versa. Five days after oral dosing, a zinc tracer was infused intravenously. FZA was measured with the use of a modified double isotope tracer ratio method with urine samples collected on days 5-7 and 10-12 of absorption studies.


RESULTS
Plasma and urinary zinc did not vary by dietary period. Mean FZA was greater from low-zinc meals than from adequate-zinc meals (60.9% +/- 13.8% compared with 36.1% +/- 8.9%; P < 0.0001), whereas mean total absorbed zinc was greater from adequate-zinc meals than from low-zinc meals (3.60 +/- 0.91 compared with 2.48 +/- 0.56; P < 0.0001), regardless of the longer-term dietary period.


CONCLUSIONS
FZA was inversely related to current zinc intake, but there was no detectable effect of longer-term dietary zinc. If longer- term zinc intake does modify FZA, such changes are smaller than those caused by current zinc intake, or they occur only after more severe zinc depletion.
Chung
Carolyn S
CS
Children's Hospital of Oakland Research Institute, Oakland, CA, USA.
Stookey
Jodi
J
Dare
Doris
D
Welch
Ross
R
Nguyen
Tuan Q
TQ
Roehl
Raimund
R
Peerson
Janet M
JM
King
Janet C
JC
Brown
Kenneth H
KH
D000328:Adult; D001682:Biological Availability; D018592:Cross-Over Studies; D004032:Diet; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior; D006801:Humans; D007201:Indicator Dilution Techniques; D007408:Intestinal Absorption / Q000187:drug effects; D007553:Isotope Labeling; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D015032:Zinc / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D015033:Zinc Isotopes
D015033:Zinc Isotopes; D015032:Zinc