Malnutrition is Associated With Altered Gut Microbial Functions in 13-Year-Old Brazilian Children

OBJECTIVES: Under- and over-nutrition are increasingly present in low- and middle-income settings, leading to a double burden of malnutrition at a population or individual level. The gut microbiota may affect host's health via dietary component degradation for energy provision and maintenance of a homeostatic gut environment. This relationship may reshape during adolescence, corresponding to the last step of gut microbiota maturation, yet remains under-investigated. The objective of the work was to assess if gut microbial functions vary with body mass index-for-age and height-for-age z-scores (BMIZ, HAZ) in adolescents and if they are influenced by sex and pubertal stage. METHODS: 340 13-year-old children (53% males) with no antibiotic use within the last 6 weeks from the 2004 Pelotas Birth Cohort, Brazil, were stratified using WHO cutoffs for BMIZ (wasting (n = 11); normal (n = 251); overweight/obese (n = 78)) and HAZ (stunting (n = 10); normal (n = 330)). Tanner staging was used to assess pubertal development (1 (n = 12); 2–4 (n = 212); 5 (n = 116)). Fecal microbiota was assessed via Illumina MiSeq (16S rRNA gene sequencing) and functions were inferred with PICRUSt2 and MetaCyc. Data were analyzed via DESeq2 in R. RESULTS: 340 pathways were identified and 19 were differently represented (q-value < .05) according to BMIZ but not HAZ. Between overweight/obese and normal, these included 16 pathways important for energy metabolism and production of various metabolites such as Preq(0); sex and pubertal stage accounted for differential representation of 8 of them. Using the wasting category as a comparator, 4 pathways related to vitamin B12 synthesis/salvage (accounted for by sex and pubertal stage) and sugars utilization were differentially represented in normal and overweight/obese categories. CONCLUSIONS: These findings suggest that the functional potential of the adolescent gut microbiota is altered with BMIZ and may be a target, with sex and pubertal stage consideration, for interventions aimed at sustaining adolescent health. FUNDING SOURCES: Joannah and Brian Lawson Centre for Child Nutrition, University of Toronto, Canada, CONACyT scholarship, Wellcome Trust, World Health Organization, National Support Program for Centers of Excellence, Brazilian National Research Council, Brazilian Ministry of Health, Children's Pastorate.