Serum extracellular superoxide dismutase activity as an indicator of zinc status in humans

The present study focused on whether serum extracellular superoxide dimutas e (EC-SOD) activity can be used as a functional indicator of marginal zinc deficiency in humans. Subjects in this study were 444 healthy adults over 3 0 yr of age living a normal rural life in Kyunggi province, Korea. The mean dietary zinc intake of subjects obtained from one 24-h recall was 6.41 +/- 4.35 mg and the average serum zinc concentration of the subjects was 11.06 +/- 2.44 mu mol/L. Subjects were divided into three groups by serum zinc c oncentrations: adequate (serum zinc > 10.7 mu mol/L), low (serum zinc 9.0-1 0.7 mu mol/L), and very low (serum zinc < 9.0 mu mol/L) groups. A total of 50 subjects were selected from the three,groups for analysis of EC-SOD acti vities. The EC-SOD activity of subjects increased with increasing serum zin c concentrations, and the activities of the three groups were significantly different as indicated by the Kruskal-Wallis test (P = 0.0239). Also, seru m EC-SOD activities were significantly correlated with serum zinc concentra tions (r = 0.289, p = 0.04). Serum EC-SOD activities, however, were not sig nificantly correlated to the dietary zinc intakes. In conclusion, these res ults show that EC-SOD activities are decreased in subjects with low serum z inc concentrations and suggest that EC-SOD activity may be a functional ind icator of zinc nutritional status in humans.