SELENIUM AND OXYGEN-METABOLIZING ENZYMES IN ELDERLY COMMUNITY RESIDENTS - A PILOT EPIDEMIOLOGIC-STUDY

Objective: To investigate the relationship of selenium and oxygen-deactivating enzymes with age in the elderly. Sample: The study sample consisted of volunteers recruited from the PAQUID study. This study is conducted in a representative sample of non-institutionalized individuals aged greater-than-or-equal-to 65 years living in Southwestern France; its main objective is to study longitudinally the incidence and risk factors of dementia. Methods: Plasma and erythrocyte selenium and activities of oxygen metabolizing enzymes in erythrocytes (GSH-Px, CuZn-SOD, and GSSG-RD) were measured in 239 volunteers (108 males and 131 females; mean age 73.7 years). Results: Plasma selenium (PSe) decreased significantly with age; a similar but non-significant trend was found for erythrocyte selenium (ESe). None of the enzyme activities showed a clear relationship with age. Women had significantly higher GSH-Px activities than men. For PSe levels lower than 77 ng/mL, there was a strong correlation between PSe and GSH-Px; above this value, the correlation decreased, suggesting that the selenium requirement for GSH-Px production had been satisfied. In this sample, CuZn-SOD was correlated negatively with GSH-Px (r = -0.18; P less-than-or-equal-to 0.01) and positively with GSSG-RD (r = +0.20; P less-than-or-equal-to 0.01). Conclusions: In individuals aged greater-than-or-equal-to 65 years, we found that blood selenium levels were negatively correlated with age. Our analysis of the relationship between selenium and GSH-Px activity suggests that low selenium values are associated with decreased GSH-Px activity.