Racial and demographic differences in selenium status: report from the Southern Community Cohort Study

A10

Selenium has been implicated in a variety of cancers, key among them being prostate, colon, esophageal, and gastro-intestinal cancers. Selenium, an essential micronutrient for humans, is widely distributed in tissues and fluids of the body in different forms, making measurement and interpretation of selenium status difficult. The purpose of this study was to examine the impact of demographic and lifestyle factors on selenium status.
 Assays of blood selenium were conducted for 396 individuals randomly selected from the Southern Community Cohort Study (SCCS) database (n = over 60,000 enrolled). These individuals were primarily low-income adults recruited from community health centers located in the Southeastern region of the United States. The sample was 50% African American and 50% white, and also evenly divided by gender. Selenium status was assessed in three ways: 1) Plasma selenium (measured fluorometrically) , 2) Selenoprotein-P (measured by radioimmunoassay/ELISA) and 3) Glutathione peroxidase activity (GPX; measured by the rate of oxidation of NADPH by glutathione peroxidase).
 Linear regression analyses revealed that there were racial, gender, and age group differences for Selenoprotein-P levels. Significantly (p<.01) lower levels of Selenoprotein-P were found among African Americans compared to whites, participants age 40-49 compared to those older, and among females compared to males. For plasma selenium measured fluorometrically, similar age effects were seen, and participants who currently smoked had lower levels of selenium compared to those who were former smokers (p<.001) and non-smokers (p<.001), but racial and gender differences were not significant. GPX levels were unaffected by demographic and lifestyle factors.
 The results suggest that the impact of demographic and lifestyle factors vary depending on the way selenium was measured. Further research is planned within the SCCS to evaluate the capabilities of the selenium biomarkers for predicting cancer incidence and mortality.
 Supported by NCI R01 CA92447 (SCCS)