Copper absorption during and after hypokinesia in copper supplemented and unsupplemented healthy subjects

Abstract 

Measuring copper (Cu) absorption, and serum, urinary and fecal Cu levels during and after hypokinesia (HK) and Cu supplementation, the aim of this study was to determine whether Cu deposition could be depressed significantly more with or without Cu supplementation. Studies were conducted during 30 days pre-HK, 364 days HK and 30-days post-HK. A total of 40 male healthy volunteers 24.7 ± 4.8 years of age were chosen as subjects. They were divided into four groups: unsupplemented active control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented active control subjects (SACS), and supplemented hypokinetic subjects (SHKS). Hypokinetic subjects were limited to an average walking distances of 0.5 ± 0.1 km · day⁻¹for 364 days. Active control subjects were running average distances of 5.3 ± 1.2 km · day⁻¹ for 364 days. All SHKS and SACS consume daily 54.02 μmol copper sulfate (CuSO₄).

Copper absorption, serum Cu level, and urinary and fecal Cu excretion did not change in SACS and UACS compared with their pre-HK values. During HK, Cu absorption decreased significantly (P < 0.05) with time, whereas serum Cu level, urinary and fecal Cu excretion increased significantly (P < 0.05) with time in UHKS and SHKS compared with their pre-HK values and their respective active controls (SACS and UACS). During the post-HK period, Cu absorption increased significantly (P < 0.05), whereas serum Cu level and urinary and fecal Cu losses decreased significantly (P < 0.05) in hypokinetic subjects compared with their pre-HK and control values, and by day 30 approached the control values. However, during HK and post-HK respectively, Cu absorption decreased significantly (P < 0.05) and serum Cu level as well as urinary and fecal Cu losses increased significantly (P < 0.05) and Cu absorption increased significantly (P < 0.05) and serum Cu level and Cu excretion decreased significantly (P < 0.05) more in SHKS than UHKS.

Decreased Cu absorption with Cu depletion during HK showed decreased Cu deposition. Increased Cu absorption during the post-HK period demonstrated Cu depletion. The greater Cu changes in SHKS than UHKS, during HK and post-HK, showed that Cu deposition decreased more with than without Cu supplementation. We conclude that dissociation between Cu absorption and Cu depletion showed decreased Cu deposition as the main reason for Cu depletion during HK.

Keywords: Human nutrition, Copper absorption, Copper deposition, Copper depletion, Diminished movements, Sedentary population