Dietary Zinc Protects Against Increases of MDA and r-GTP by Lead: Biological Monitoring for Environmental Surveillance

Abstract

P-147 Introduction: Lead has been reported to induce a variety of diseases including cancer through the production of oxidative stress. Malondialdehyde (MDA) and r-glutamyl transpeptidase (r-GTP) are oxidative stress markers and zinc is a major antioxidant found in food. Therefore, we hypothesized that blood lead as a biomarker of environmental lead exposure increases the levels of MDA and r-GTP as oxidative stress indicators and dietary zinc intake protects against increases of MDA and r-GTP produced by blood lead. Methods: In this study, we measured the levels of lead and r-GTP in blood and MDA in urine to evaluate the effects of blood lead and dietary zinc intake on MDA and r-GTP levels in 387 non-occupationally exposed women drawn from Biological Monitoring for Environmental Surveillance (BIOMES). In addition, we calculated the zinc intake using the information obtained from dietary questionnaire including basic characteristics such as age and smoking history. Results: When effects of blood lead and dietary zinc intake on MDA and r-GTP levels were estimated separately, the MDA and r-GTP levels showed positive relationship with blood lead level (MDA, regression coefficient = 0.1729, P = 0.0016; and r-GTP, regression coefficient = 0.1544, P = 0.0782, respectively) and negative relationship with dietary zinc intake (MDA, regression coefficient = - 0.1151, P = 0.0395; and r-GTP, regression coefficient = −0.0498, P = 0.4976, respectively). These effects were also shown after being adjusted for age, smoking status, and alcohol consumption (lead and MDA, regression coefficient = 0.1536, P = 0.0091; lead and r-GTP, regression coefficient = 0.2002, P = 0.0299; zinc and MDA, regression coefficient = −0.1101, P = 0.0560; and zinc and r-GTP, regression coefficient = −0.0490, P = 0.5386, respectively). We made lead/zinc ratio as a new exposure indicator because of potential of lead and zinc competition and then estimated the effect of lead/zinc ratio on MDA and r-GTP levels. Lead/zinc ratio showed positive relationship with MDA and r-GTP levels (MDA, regression coefficient = 0.1390, P = 0.0003; and r-GTP, regression coefficient = 0.0959, P = 0.0913, respectively). This effect was also shown after being adjusted for age, smoking status, and alcohol consumption (MDA, regression coefficient = 0.1314, P = 0.0011; and r-GTP, regression coefficient = 0.1193, P = 0.0531, respectively). Discussion and Conclusions: Our results suggest that blood lead as a biomarker of environmental lead exposure and dietary zinc intake play a role on the regulation of the levels of MDA and r-GTP, oxidative stress indicators.