Oxidative Stress and Its Relationship With Market Integration and Pathogen Exposure Among Indigenous Shuar Children of Amazonian Ecuador

Objectives: Oxidative stress (OS) plays a key role in human aging and lifelong health. Problematically, little attention has been given to OS during childhood or outside of wealthy, industrialized populations. This limits understanding of the lifestyle and environmental factors that may drive global variation in childhood OS. Here, we present multifaceted urinary OS data from Indigenous Shuar children of Amazonian Ecuador to examine how children's OS is influenced by: (1) broad differences in market integration (MI; rural vs. peri-urban living); (2) household-level predictors of pathogen exposure; and (3) physiological measures of pathogen burden (immune activity) and adversity (cortisol). Methods: Anthropometrics, household questionnaire data, and biospecimens (urine and finger-prick dried blood spots) were collected cross-sectionally from rural (n = 43) and peri-urban (n = 34) Shuar children, ages 4–12 years. 8-hydroxy-2′-deoxyguanosine (8-OHdG; a measure of oxidative damage) and total antioxidant capacity were measured in urine, and the overall oxidative stress index (OSI) was calculated. Predictors of OS were assessed using regression models. Results: Peri-urban Shuar children had, on average, 45% lower OSI than rural children (p = 0.002). Household pathogen exposure variables, including lack of running water and a greater number of resident individuals, predicted greater child OS (multiple p < 0.05). Children's physiological measures of pathogen burden (circulating total immunoglobulin E) and adversity (urinary cortisol) similarly predicted greater OS (multiple p < 0.05). Conclusions: These findings suggest that MI, including its impact on pathogen exposure and physiology, is an important driver of global variation in childhood OS and related disparities in phenotype and health.