Effects of age and sex on copper absorption, biological half-life, and status in humans.

Healthy, free-living men and women aged 20-83 y (n = 127) were studied to determine the effects of age and sex on copper absorption, biological half-life (BH), and status. Copper absorption was greater in women (71%) than in men (64%) aged 20-59 y (P = 0.02), but did not differ in men and women aged 60-83 y. BH of 67Cu ranged from 13 to 33 d and differed between men and women aged 20-59 y (P = 0.006), but not between men and women aged 60-83 y. Plasma copper, enzymatic ceruloplasmin (Cp), and immunoreactive (RID) Cp were significantly higher in women than in men (P < 0.005), but superoxide dismutase (SOD) and in vitro 67Cu uptake by red blood cells did not differ. Plasma copper, RID Cp, and cytochrome oxidase in platelets and mononuclear cells were significantly affected by age (P < 0.005). Oral contraceptives elevated plasma copper, enzymatic Cp, and SOD activity but not copper absorption and BH in women aged 20-39 y. Copper intake from self-selected diets was 0.9-1.2 mg/d for women and 1.2-1.3 mg/d for men, but net copper absorption (micrograms Cu.kg body wt-1.d-1) did not differ. Thus, dietary copper intake requirements may differ between men and women.