Changes in dietary zinc and copper affect zinc-status indicators of postmenopausal women, notably, extracellular superoxide dismutase and amyloid precursor proteins
Cd. Davis et al., Changes in dietary zinc and copper affect zinc-status indicators of postmenopausal women, notably, extracellular superoxide dismutase and amyloid precursor proteins, AM J CLIN N, 71(3), 2000, pp. 781-788
Background: Zinc is an essential trace element for human health and well-be
ing; however, methods currently available for the assessment of zinc status
in humans are unsatisfactory.
Objective: The objective was to critically evaluate the use of various indi
cators of zinc status in humans in a controlled metabolic ward study.
Design: Indicators of zinc status were measured in 25 healthy postmenopausa
l women aged 64.9 +/- 6.7 y. After a 10-d equilibration period, volunteers
consumed a diet with either a low (1 mg/d; II = 12) or a high (3 mg/d; n =
13) copper content based on a total energy content of 8.4 MJ. They received
the same amount of copper throughout the study. Both groups were fed the b
asal diet (3 mg Zn/d) with no zinc supplement for one 90-d period, and the
diet supplemented with 50 mg Zn/d for another 90-d period.
Results: Zinc supplementation significantly increased (P < 0.0001) extracel
lular but not erythrocyte superoxide dismutase activity. This increase was
more apparent when subjects were fed the low-copper diet. Zinc supplementat
ion in combination with the low-copper diet significantly decreased (P < 0.
01) amyloid precursor protein expression in platelets. Other indicators of
zinc status that were significantly elevated after zinc supplementation wer
e as follows: plasma zinc and free thyroxine concentrations and mononuclear
5'-nucleotidase activity.
Conclusion: The measurement of serum extracellular superoxide dismutase act
ivity may be useful as a marker for the functional assessment of zinc statu
s in humans.