Influence of Lactobacillus casei Shirota supplementation, insulin resistance and diet on gut microbiota, gut permeability and bile acid profile in patients with metabolic syndrome

Background: Metabolic syndrome (MetS) is associated with disturbances in gut microbiota. In animal models, modulation of gut microbiota by probiotic supplementation is possible. However, data in humans are scarce and controversial.

Aim: To study whether probiotic supplementation, insulin resistance (IR) or diet impact on gut microbiota composition, gut barrier integrity and inflammation or bile acid profile in MetS.

Methods: In a single-centre, prospective, randomised controlled pilot study, 28 subjects with MetS received either Lactobacillus casei Shirota (LcS) for 12 weeks (n = 13) or no LcS (n = 15). Data were compared to healthy controls (n = 16). Gut microbiota composition was characterised from stool using 454 pyrosequencing of 16S rRNA genes. Serum bile acids were quantified by tandem mass spectrometry. Zonulin and Calprotectin were measured in serum and stool by ELISA. A food frequency questionnaire was used to measure eating habits.

Results: Bacteroidetes/Firmicutes ratio was significantly higher in healthy controls compared to MetS but was not influenced by LcS. LcS supplementation lead to enrichment of Parabacteroides. IR was associated with higher abundance of Bacteroides and Sutterella and lower abundance of Ruminococcus. Zonulin and Calprotectin were increased in MetS stool samples but not influenced by LcS, IR or high fat consumption. Serum bile acids were similar to controls and not influenced by LcS supplementation or IR. High fat consumption resulted in lower levels of water-soluble bile acids.

Conclusions: LcS administration was associated with subtle microbiota changes at genus level. High fat consumption but not LcS supplementation or IR seems to impact on bile acid profile.