Linking gut redox to human microbiome

Uncontrolled oxidative stress has been associated with many diseases and aging. We previously report an increased gut redox and depletion of the anaerobic microbiome in severe acute malnutrition. Here, we extended the analysis to test if this link could be generalized by including individuals with various age and dietary status. Seventy individuals (children and adults, French and African, healthy individuals and teenagers with anorexia nervosa, marasmus and kwashiorkor) were included. Fecal redox potential was measured using a simple redox probe. v3v4 16S gene targeted metagenomics was used to characterize the microbiota. The Metagenomic Aerotolerant Predominance Index (MAPI) was defined as the natural logarithm of the ratio of the relative abundance of aerotolerant on strict anaerobic species. This index is easily understandable (MAPI > 0: aerotolerant predominance, MAPI < 0: anaerobic predominance), can be calculated for any metagenome and follows a normal distribution among our 70 included individuals. Fecal redox potential (mV) and the Metagenomic Aerotolerant Predominance Index were dose-dependently related (linear regression, p < .001). This link, if confirmed, will allow humans to take care of their microbiome and prevent, treat and/or alleviate gut redox associated chronic diseases by (i) controlling the concentration of reactive species in the gut by avoiding behavior associated with uncontrolled oxidative stress (alcoholism,…) in the gut and using reduced water, and (ii) by improving gut anti-oxidant capacities by an adequate diet rich in nutrients allowing the human gut to maintain a very low redox potential in the gut as a key for homeostasis.