Zinc measurements during hypokinesia and zinc supplementation in determining zinc retention during hypokinesia in normal subjects

Abstract

Measuring zinc (Zn) retention, Zn balance, serum, fecal and urinary Zn levels with and without Zn supplementation, the aim of this study was to show if hypokinesia (HK) could contribute to the smaller Zn retention and consequently to the development of Zn imbalance. Studies were conducted during 30 days pre-HK and 364 days HK. Forty male normal individuals 23. 8 ± 5.0 years of age were chosen as subjects. They were equally divided into four groups: unsupplemented active control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented active control subjects (SACS) and supplemented hypokinetic subjects (SHKS). All SHKS and UHKS were walking average distances of 0.5 km.day-l, while SACS and UACS were running average distances of 9.1 km.day-l. All SHKS and SACS consume daily 30 mg Zn. Zinc retention decreased significantly (p < 0.05) with time, while Zn imbalance, serum Zn level, fecal and urinary Zn excretion increased significantly (p < 0.05) with time in SHKS and UHKS compared with their pre-HK values and the levels in their respective active controls (SACS and UACS). However, Zn retention decreased significantly (p < 0.05) more with time, while Zn imbalance, and Zn levels in serum, feces and urine increased significantly (p < 0.05) more with time in SHKS than UHKS. Conversely, Zn retention, Zn balance, serum Zn level, urinary and fecal Zn excretion did not change in SACS and UACS compared with their pre-HK control values. Significant increase of Zn losses with Zn imbalance and Zn supplementation may demonstrate decreased Zn retention. Significantly higher Zn loss in SHKS than UHKS may demonstrate that Zn is wasted more with than without Zn supplementation. It was concluded that dissociation between Zn loss from the body and Zn imbalance may demonstrate the presence of decreased Zn retention as the mechanism of development of Zn depletion during prolonged HK.