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Pure Appl. Chem., 2012, Vol. 84, No. 2, pp. 325-333

Published online 2011-12-29

Studies on variation in fecal reactive oxidative species generation in free-living populations in Guatemala

Mónica N. Orozco1*, Noel W. Solomons1, Claudia Arriaga1, Liza Hernández1, Raquel Campos1, María José Soto1 and Klaus Schümann2

1 Center for the Studies of Sensory Impairment, Aging, and Metabolism (CeSSIAM), 17a Avenida 16-89 (interior) Zona 11, Guatemala City, Guatemala
2 Research Center for Nutrition and Food Science, Technische Universität München, Gregor-Mendel-Strasse 2, Freising-Weihenstephan, Germany

Abstract: Among the factors associated with the risk of colorectal cancer and other large bowel diseases are gender, with women having lower incidence than men, and free-radical mediated oxidation. Dietary fiber has been attributed a protective role in human gastro-intestinal health. The main aim of this study was to determine the degree of association between dietary fiber consumption and fecal free-radical production in healthy rural and urban Guatemalan women, moreover, to look for associations between gender and fecal reactive oxidative species (ROS) basal production, a marker of in situ colonic free-radical-based oxidation. For this purpose, we assessed the dietary fiber consumption, using two 24-h recalls, in urban and rural females, and compared the baseline data, i.e., of iron-supplement-free periods, in three previous studies. Two of these trials quantified the fecal ROS generation as total hydroxylated products resulting from free-radical attack on salicylic acid along with residual non-heme iron content in stool samples from 27 Fe-replete men. The third study assessed the same variables in 20 rural and 20 urban women, all consuming their respective habitual diets. The average fiber consumption for females was more than double in the rural group than in the urban population. As for the average ROS responses, a 2.5-fold difference was observed between men and women, with men having the higher concentrations of total hydroxylated products. This difference was sex-linked, unaffected by statistically significant differences in dietary fiber intake, nor by different concentrations of residual fecal non-heme iron between rural and urban women. The difference in background ROS production between men and women suggests a gender-related influence on intraintestinal oxidation that may protect women from harmful effects of dietary oxidants, such as iron.