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

Abstract

The present study focused on whether serum extracellular superoxide dimutase (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 30 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 micromol/L. Subjects were divided into three groups by serum zinc concentrations: adequate (serum zinc >10.7 micromol/L), low (serum zinc 9.0-10.7 micromol/L), and very low (serum zinc <9.0 micromol/L) groups. A total of 50 subjects were selected from the three groups for analysis of EC-SOD activities. The EC-SOD activity of subjects increased with increasing serum zinc concentrations, and the activities of the three groups were significantly different as indicated by the Kruskal-Wallis test (p = 0.0239). Also, serum EC-SOD activities were significantly correlated with serum zinc concentrations (r = 0.289, p = 0.04). Serum EC-SOD activities, however, were not significantly correlated to the dietary zinc intakes. In conclusion, these results show that EC-SOD activities are decreased in subjects with low serum zinc concentrations and suggest that EC-SOD activity may be a functional indicator of zinc nutritional status in humans.

Zinc intake and status in middle-aged and older European subjects: the ZENITH study

“…In our population, we did not observe gender differences for Zn status, which is in line with the similar findings in a number of studies (Rukgauer et al, 1997;Paik et al, 1999;Diaz Romero et al, 2002). However, Schumacher et al (1994) reported a higher serum mean Zn concentration in female subjects.…”

“…Indeed, the mean daily Zn intakes reported here are higher than the intakes measured in a previous study older French men, using duplicate diets (Pelus et al, 1994). They were also higher than those measured from the Third National Health And Nutrition Examination Survey (NHANES), which showed that people older than 71 y (n ¼ 2623) had a mean dietary Zn intake (ie from food sources only) of 9.2 mg/day and the total daily Zn intake rose to 12.7 mg/day when Zn from supplements were accounted for (Paik et al, 1999). In middle-aged, but not in older, women Zn intake was lower compared to men (10.0574.48 mg/day vs 11.9773.11 mg/day, Po0.0001), reflecting gender-specific differences in dietary habits.…”

Introduction to the ZENITH study and summary of baseline results

“…These older European subjects for the most part had adequate Zn intakes. These data on European population are consistent with data from others studies carried out in the US, underlying similar habits in Zn intake in developed countries (Paik et al, 1999). The descriptive analysis showed also that there are only modest differences in the nutrient intake and vitamin nutritional status in the middle-aged and older inhabitants of the three European regions.…”

Extracellular superoxide dismutase (ecSOD) in vascular biology: an update on exogenous gene transfer and endogenous regulators of ecSOD

“…63,64 Although positive correlations between zinc levels and ecSOD activities were observed in the animal studies, such correlations have not been observed consistently in humans. Paik et al 65 reported that in healthy adult Koreans, ecSOD activity correlated positively with increasing serum zinc concentrations. Interestingly, SOD1 activity correlated negatively with zinc, which suggests that SOD1 and ecSOD are regulated differentially by this cation.…”