Cross‐sectional comparisons of gut microbiome and short‐chain fatty acid levels among children with varied weight classifications

Abstract

Summary Background Limited studies associate changes in microbiota composition and metabolites among children and adolescents with obesity. Decreases in compositional diversity, increases in the proportion of Firmicutes and Bacteroidetes (F/B ratio) and increases in short‐chain fatty acids (SCFAs) have been proposed as contributing factors in the pathophysiology of obesity. Objectives The aim of the current study was to characterize the faecal microbiota composition, diversity, F/B ratio and SCFA levels in different weight categories (lean, overweight, obesity classes 1‐3) of children ages 5 to 12 years. Methods We collected and processed 83 samples from different weight categories (27.7% lean, 11% overweight, 15%, 17% and 17% of obesity classes 1, 2, and 3, respectively). Microbiota content was determined by sequencing the V4 region of the 16S rRNA gene, and SCFA content was analyzed. Results Microbiota compositions showed no significant differences in diversity or F/B ratios between weight categories. However, a relative abundance of Proteobacteria and lack of Verrucomicrobia were demonstrated when comparing severe obesity to the leaner groups. Faecal butyrate, propionate and isopentanoate concentrations increased progressively with weight category demonstrating significance in the class 3 obesity group. Conclusions Our results show that severe childhood obesity in our study population was associated with changes in gut microbiome composition correlated to previously reported cardiometabolic disease states in obesity. Increased SCFA levels correlate with obesity‐related microbiome metabolic function without a reduction in diversity characterized at a phyla level. Further characterization of these specimens at a species level and longitudinal studies are needed to elucidate these relationships.

Roles of gut microbiota and metabolites in overweight and obesity of children

“…The abundance of Verrucomicrobia is relatively low in the human gut microbiota. However, recent research has shown that the abundance of Verrucomicrobia was low in obese children ( 38 , 39 , 60 ), and it has vital benefits. Hence, it is a potential probiotic against metabolic inflammation and obesity ( 61 ).…”

“…The concentration of SCFAs in obese children is low ( 106 ), however, some studies have shown high levels of acetate, propionate, butyrate, and isovalerate in obese children ( 31 , 38 , 99 ), which are positively correlated with BMI z-scores ( 31 ). Despite the potential benefits of SCFAs, the overall function of SCFAs in pediatric overweight/obesity remains unclear.…”

Fecal microbiota relationships with childhood obesity: A scoping comprehensive review

“…Therefore, it has become essential to analyze maternal, prenatal, infant, and childhood interactions that could impact infant's health 19 . Childhood obesity is accompanied by shifts in the composition of fecal microbiota with differences between obese and non‐children with obesity (Table 1), 20 which may be accompanied by changes in short‐chain fatty acid levels, potentially associated to the abundance of Proteobacteria 21 or involving fat distribution features in children 22 …”

“…18 Therefore, it has become essential to analyze maternal, prenatal, infant, and childhood interactions that could impact infant's health. 19 Childhood obesity is accompanied by shifts in the composition of fecal microbiota with differences between obese and non-children with obesity (Table 1), 20 which may be accompanied by changes in shortchain fatty acid levels, potentially associated to the abundance of Proteobacteria 21 or involving fat distribution features in children. 22 These studies have shown that those children presenting overweight or obesity had a similar microbial profile to each other, being different from the gut microbiota in children with normal-weight as reported in a Chinese pediatric population.…”

Composition and Functions of the Gut Microbiome in Pediatric Obesity: Relationships with Markers of Insulin Resistance

“…However, it remains unclear whether these microbial imbalances were a causal factor in the development of obesity. Moreover, many studies have profiled the gut microbiota of children and adolescents using 16S rRNA gene amplicon sequencing to compare taxonomic composition across weight status [ 41 , 42 , 43 , 44 ], but only a few have explored the associations between markers of insulin resistance and gut microbiome functions [ 36 , 37 , 38 , 45 , 46 ]. None of these studies have used shotgun metagenomics, which is a more robust approach allowing researchers to catalogue all genes present in a sample, identify the taxonomic composition at a species level resolution, and characterize the functional potential of the gut microbiome [ 47 ].…”