Impact of a carbohydrate-rich diet on gut microbiota composition and enterococcal dynamics

Abstract

Excessive consumption of refined carbohydrates from processed foods is increasingly associated with intestinal dysbiosis and metabolic disturbances. The present study aimed to evaluate the impact of a carbohydrate-rich diet, using processed white bread as the main source, on the dynamics of enterococci in comparison with beneficial bacteria (bifidobacterial and lactobacilli) and opportunistic Escherichia coli in an experimental animal model. Laboratory rats were divided into control (standard diet) and experimental groups (highcarbohydrate diet), and intestinal bacterial counts were assessed at baseline, after 5, 10, and 15 days of dietary intervention, and following a 7-day recovery period. Microbial populations were quantified and expressed as log CFU/g. The high-carbohydrate diet induced a significant reduction in enterococci (up to 21%) and bifidobacteria (up to 22.2%), accompanied by a moderate decrease in lactobacilli and an increase in E. coli populations during the early phase of intervention. Restoration of the standard diet partially or completely reestablished microbial balance. These findings suggest that processed carbohydrate excess disrupts intestinal microbial homeostasis, highlighting the sensitivity of enterococci to dietary carbohydrate shifts and supporting their potential commensal role in gut ecosystem stability.