Zinc absorption adapts to zinc supplementation in postmenopausal women.
OBJECTIVE
To determine if human Zn absorption adapts to chronic high Zn intakes.


METHODS
Zn absorption was measured at 0, 8, and 16 wk in healthy postmenopausal women who consumed controlled diets with approximately 5 mg Zn from food, supplemented to 14 (n = 6), 32 (n = 3), or 47 (n = 3) mg Zn/d for 22 wk. Zn absorption for 1 day was determined by (65)Zn-labeling of meals and whole body scintillation counting.


RESULTS
At wk 0, less Zn was absorbed from diets with 14, compared with 32 or 47 mg/d (4.6, 8.7, and 10.3 mg/d, respectively; pooled SE = 0.9; p < 0.05). These differences were not apparent at wk 8 (5.4, 5.8, 6.4; NS) and became negligible by wk 16 (5.0, 5.0, 5.1; NS). Plasma Zn concentrations were unaffected. The results are consistent with a saturation response model of Zn absorption.


CONCLUSIONS
Within several weeks, postmenopausal women biologically adapted to absorb a relatively uniform amount of 5 mg Zn/d when controlled, Zn-supplemented diets supplied consistent Zn intakes between 14 and 47 mg/d.
Beiseigel
Jeannemarie M
JM
US Department of Agriculture, ARS, GFHNRC, University of North Dakota, PO Box 9034, Grand Forks, ND 58202-9034, USA.
Klevay
Leslie M
LM
Johnson
LuAnn K
LK
Hunt
Janet R
JR
D000222:Adaptation, Physiological; D000368:Aged; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008875:Middle Aged; D017698:Postmenopause / Q000378:metabolism*; D015032:Zinc / Q000008:administration & dosage / Q000493:pharmacokinetics*
D015032:Zinc