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Healthy postmenopausal women adapt to reduce zinc absorption in response to zinc supplementation
Author(s) -
Beiseigel Jeannemarie M.,
Klevay Leslie M.,
Hunt Janet R.
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.20.5.a985
Subject(s) - zinc , absorption (acoustics) , chemistry , zoology , medicine , endocrinology , blood plasma , postmenopausal women , biochemistry , biology , materials science , organic chemistry , composite material
To assess adaptation to chronic Zn supplementation, Zn absorption was measured in healthy, postmenopausal women fed a low‐Zn diet (3‐6 mg Zn/d) with 9, 27, or 42 mg Zn/d added with meals for 22 wk (n=6, 5, or 5, respectively). The diet contained 1.1 mg Cu. 65 Zn labeled meals fed for 1 d at wks 0, 8, and 16 were followed by serial whole body counting to measure Zn absorption. Plasma Zn, Cu, and blood lipids were measured throughout the 22 wk of the study. Repeated measures and mixed‐models ANOVAs assessed changes in absorption and biochemical parameters, respectively. For women supplemented with 9, 27, or 42 mg Zn, respectively, initial differences in absorption (4.6 a , 8.9 b , and 9.2 b mg/d; p<0.01), were no longer significant at 8 wk (5.4 a , 5.9 a , and 7.0 a ; NS), and were negligible by 16 wk (5.0 a , 4.8 a , and 4.8 a ; NS) (pooled SE = 0.7). Despite adaptations in absorption, plasma Zn increased with 27 mg (61 ± 15 vs. 81 ± 12 μg/dL, for 0 vs. 22 wk, p<0.05) and 42 mg added Zn (72 ± 11 vs. 106 ± 34 μg/dL; p<0.0001) but not with 9 mg added Zn (77 ± 3 vs. 80 ± 4 μg/dL, NS). Zn supplementation did not significantly change plasma Cu or blood lipids. The nearly complete adaptation in Zn absorption after 16 wk, with an elevation in plasma Zn that persisted through 22 wk, suggests that Zn distribution or excretion did not adapt to equilibrate plasma Zn within this time. The absorptive adaptation suggests no benefit of Zn intakes greater than 12–15 mg/d. However, it is unclear whether the sustained increase in plasma Zn, resulting from early differences in absorption without apparent excretion, represents a benefit or detriment.