Reduced Dietary Intake Of Carbohydrates By Obese Subjects Results In Decreased Concentrations Of Butyrate And Butyrate Producing Bacteria In Feces

Researchers studied how different levels of carbohydrate intake affect gut bacteria in 19 obese adults. Participants followed three diets in sequence: a maintenance diet with normal carbs (399g daily), then a high-protein medium-carb diet (164g carbs daily), and finally a high-protein very low-carb diet (24g carbs daily). Each diet phase lasted several weeks, and stool samples were analyzed to measure bacteria types and beneficial compounds they produce.

The study found that as carbohydrate intake decreased, levels of butyrate dropped dramatically - from 18mM on the normal diet to just 4mM on the very low-carb diet. Butyrate is a short-chain fatty acid that serves as fuel for colon cells and helps maintain gut barrier function. The researchers also observed significant decreases in specific beneficial bacteria, particularly Roseburia species and Eubacterium rectale, which are major butyrate producers in the gut.

While low-carb diets can be effective for weight loss and may improve insulin sensitivity, this research suggests they might have unintended consequences for gut health. The reduction in butyrate-producing bacteria could potentially impact colon health over time, since butyrate plays important roles in reducing inflammation and supporting the intestinal lining.

This research highlights the importance of considering gut microbiome health when choosing dietary approaches for weight management. In clinical practice, this suggests that patients following very low-carb diets might benefit from strategies to support beneficial gut bacteria, such as including fiber-rich, low-glycemic vegetables or considering targeted probiotic supplementation.