ZINC AND COPPER BALANCES IN HEALTHY ADULT MALES DURING AND AFTER 17 WK OF BED REST

The effects of long-term bed rest on zinc and copper balances were mea sured in seven healthy men. Volunteers aged 22-54 y (xBAR +/- SD, 34 /- 12 y), 168-185 cm in height (173 +/- 5 cm), and 64-86 kg in weight (74 +/- 9 kg) remained on a metabolic ward for 29 wk. Subjects were am bulatory during weeks 1-5, remained in continuous bed rest for weeks 6 -22, and were reambulated during weeks 23-29. Copper and zinc were mea sured in weekly urine and fecal composites. Dietary intakes provided ( xBAR +/- SD) 19.2 +/- 1.2 mumol Cu (1.22 +/- 0.08 mg), 211 +/- 11 mumo l Zn (13.81 +/- 0.72 mg), 25.2 +/- 1.2 mmol Ca (1011 +/- 46 mg), 1086 +/- 46 mmol N (15.21 +/- 0.65 g), and 48.1 +/- 1.4 mmol K (1489 +/- 44 mg)/d. Bed rest increased fecal zinc excretion and decreased zinc bal ance, whereas copper balance was unchanged. Reambulation decreased fec al zinc excretion and increased both zinc and copper balances. These r esults suggest that during long-term bed rest or space flight, individ uals will lose total body zinc and will retain more zinc and copper wh en they reambulate.