Impact of the ketogenic diet on human gut

Background The classic ketogenic diet (KD) is an normocaloric dietary protocol with a high intake of fats (85-90% of energy), which is used as a therapy for drug-resistant epilepsies and type 1 glucose transporter deficiency syndromes (GLUT1-DS). It is known that specific dietetic patterns can influence the composition of the intestinal microbiota; in particular, it was shown that KD is associated with various pro-inflammatory changes in the microbiota. Aim To verify the impact of KD on the intestinal microbiota, through the evaluation of: intestinal bacterial composition, markers of bacterial metabolism (short chain fatty acids, SCFA), toxicity of faecal water. Materials and Methods Faecal samples were collected in 12 patients with GLUT1-DS or drug-resistant epilepsy (KD) and in matched healthy subjects (CTR); additionally, in 7 patients samples were collected also before the dietary treatment. The bacterial composition was evaluated by analysis of Next Generation Sequencing and Real-Time PCR. SCFAs were measured by gas-chromatography. Toxicity of faecal water was assessed by Trypan Blue (cytotoxicity) and Comet Assay (genotoxicity). Results The microbiota composition of KD patients was significantly different than CTR, especially for a different Firmicutes /Bacteroidetes ratio. SCFA decreased significantly during a KD, as well as the level of genotoxicity of faecal water. Conclusions This study confirmed the impact of KD on the intestinal microbiota, highlighting the need for further research to avoid long-term adverse effects and optimize therapy.