Free acid β-hydroxybutyrate supplementation does not ameliorate dextran sodium sulfate-induced colitis similar to ketogenic diet in male mice

High-fat, low-carbohydrate ketogenic diets have been found to alleviate experimental colitis in rodents. These diets lead to increased endogenous production and utilization of ketone bodies, such as β-hydroxybutyrate (BHB), and supplementation with exogenous ketones has arisen as a potential alternative to ketogenic diets. This study aimed to investigate how continuous high-dose feeding with free acid BHB influences experimental colitis compared to a ketogenic diet with the hypothesis that BHB would also alleviate the inflammation. We fed nine-week-old C57BL/6 J male mice for four weeks with one of three diets: a low-fat control diet, a ketogenic diet, or a low-fat diet supplemented with free acid R-BHB and then induced colonic inflammation with dextran sodium sulfate (DSS). We assessed macroscopic and histological changes in the colon, intestinal permeability to fluorescein isothiocyanate dextran, colonic mRNA expression of tight junction proteins and inflammatory markers, fecal calprotectin, and microbiota composition. While the ketogenic diet alleviated DSS-induced weight loss, macroscopic changes, and histological lesions, the BHB-supplemented diet did not have the same effect. The pre-DSS composition of the microbiota was drastically different between the diet groups which may partly explain the different outcomes. In conclusion, high-dose supplementation with free acid BHB may not produce the same benefits as ketogenic diet in the context of colonic inflammation. • Ketogenic diet (KD) protected from dextran sodium sulfate-induced colitis in mice • Protective effect was not recapitulated by β-hydroxybutyrate (BHB) supplementation • KD resulted in notably different fecal microbiota profile than BHB supplementation • Changes in microbiota may partly explain the different outcomes