Determinants of oxidative stress among indigenous populations in Northern Laos: Trace element exposures and dietary patterns.

OBJECTIVES: To investigate determinants of oxidative stress in an indigenous population, we examined associations of trace element exposures and dietary patterns with three oxidative stress-related biomarkers among indigenous populations in Northern Laos. METHODS: This cross-sectional study included 341 adults from three villages with different levels of modernization. We used three oxidative stress-related biomarkers: urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-isoprostane concentrations, which were measured using liquid chromatography-tandem mass spectrometry, and blood telomere lengths, which were measured using a quantitative polymerase chain reaction method. We used multilevel analysis to examine associations of urinary arsenic, cadmium, and selenium concentrations, their interaction terms, and wild-plant-food scores (principal component scores calculated from food consumption frequencies) with oxidative stress-related biomarkers. RESULTS: Urinary arsenic and cadmium concentrations were positively associated with urinary 8-isoprostane concentrations. Urinary selenium concentrations were positively associated with urinary 8-OHdG concentrations. Interaction terms ([arsenic or cadmium] × selenium) showed negative associations with urinary 8-OHdG and 8-isoprostane concentrations, respectively. Urinary cadmium concentrations were negatively associated with telomere lengths. Wild-plant-food scores did not exhibit associations with oxidative stress-related biomarkers. CONCLUSION: Our findings imply that exposure to arsenic and cadmium is associated with greater oxidative lipid damage, whereas selenium may attenuate arsenic-induced oxidative DNA damage and cadmium-induced oxidative lipid damage. Cadmium exposure may accelerate telomere attrition. Trace element exposure may be a determinant of oxidative stress among indigenous populations in Northern Laos.

Changes in oxidative stress levels during two weeks of smoking cessation treatment and their association with nutritional characteristics in Japanese smokers.

Although several experimental studies have reported that oxidative stress levels decrease during smoking cessation, how they change among general smokers has yet to be completely elucidated. In the present study, a total of 23 smokers who underwent smoking cessation treatment were observed for two-week changes in their levels of 8-OHdG and 8-isoprostane. Physical and nutritional characteristics were measured at the initial patient visit, and casual urine samples were collected at the initial visit and at a follow-up visit two weeks later. Oxidative stress was measured by a high performance liquid chromatography electrochemical detector, and the two-week difference in the levels of oxidative stress was assessed according to demographic and nutrient factors. Neither the urinary level of 8-OHdG nor that of 8-isoprostane decreased, although the cotinine level was decreased at two weeks. A Two-way repeated ANOVA revealed a significant interaction for fat intake by time for the change in the 8-OHdG level (P=0.03) and significant interactions for α-tocopherol intake (P=0.03), iron intake, and carbohydrate intake (P=0.03), all of which were time-dependent for the change in the 8-isoprostane level. The 8-OHdG level decreased among smokers with a high fat intake and was increased with a low fat intake. The 8-isoprostane levels were decreased among smokers with a high carbohydrate intake and increased with a low carbohydrate intake, decreased with a low iron intake and increased with a high iron intake and decreased with a low α-tocopherol intake and increased with a high α-tocopherol intake. Although the present study failed to observe a decrease in oxidative stress levels during the two-week smoking cessation period, we hypothesize that the intake levels of specific nutrients when initiating smoking cessation treatment may predict any subsequent changes in the oxidative stress levels.