Childhood obesity, dietary patterns and gut microbiota: a narrative review

Childhood obesity is an emerging and multifactorial public health challenge resulting from the interaction of genetic, metabolic, social, and cultural determinants. Dietary habits are particularly relevant, as they are central to the regulation of energy balance. Indeed, gut microbiota seems to be a target factor to prevent and treat obesity. This narrative review aims to evaluate the gut microbiota in children suffering from obesity, and to assess how different dietary patterns affect these children’s gut microbiota. A comprehensive literature review conducted through the PubMed database identified 20 studies on gut microbiota and obesity in children, and 15 studies on the impact of different diets (Vegetarian, Western, Mediterranean) on the gut microbiota, with bacterial taxa names updated to the latest 2024 nomenclature. The bacillota phylum appears to be increased in individuals with obesity, while the bacteroidota phylum, on the contrary, is decreased, resulting in an increased Bacillota/Bacteroidota (B/B) ratio in children leading with obesity. The Mediterranean diet has been shown to improve bacterial diversity and to reduce inflammation, contrary to the Western diet (WD). Vegetarian diets have been shown to be a beneficial way to promote Short Chain Fatty Acids (SCFA) production. Additional larger studies are needed to evaluate this issue, as differences in findings are observed, especially in pediatric population, when assessing the gut microbiota. Children with obesity show an increased bacillota and a decreased bacteroidota phylum. Pediatric subjects with obesity appear to have a higher bacillota/bacteroidota (B/B) ratio. The Mediterranean and Vegetarian diets enhance bacteria diversity, contrary to the Western diet.