Short communication: Effect of supplementation with Lactobacillus casei Shirota on insulin sensitivity, beta-cell function, and markers of endothelial function and inflammation in subjects with metabolic syndrome-A pilot study

Based on animal studies, intake of probiotic bacteria was suggested to improve insulin sensitivity by reducing endotoxinemia and inflammation. The objective of this study was to determine the effects of supplementation with the probiotic strain Lactobacillus casei Shirota (LcS) over 12 wk on insulin sensitivity, beta-cell function, inflammation, and endothelial dysfunction parameters in subjects with metabolic syndrome. In a randomized-controlled study, 30 subjects with metabolic syndrome either received Lactobacillus casei Shirota 3 times daily for 12 wk or served as controls with standard medical therapy. Fasting blood samples were taken and a 75-g oral glucose tolerance test was performed to derive indices for insulin sensitivity and beta-cell function. In addition, parameters to assess endothelial function and inflammation markers were determined. Even though the insulin sensitivity index significantly improved after 3 mo of probiotic supplementation (0.058 +/- 0.021 vs. 0.038 +/- 0.025), the change was not significantly different compared with the control group. No improvements were seen in additional indices of insulin sensitivity (quantitative insulin sensitivity check index, insulin sensitivity by oral glucose tolerance test, and homeostasis model assessment for insulin resistance) and beta-cell function (first and second phase insulin secretion, and homeostasis model assessment for beta-cell function). Probiotic supplementation resulted in a significant reduction in soluble vascular cell adhesion molecule-1 (sVCAM-1) level (1,614 +/- 343 vs. 1,418 +/- 265 ng/mL). No significant changes in parameters used to assess low-grade inflammation or endothelial dysfunction were observed. Intake of LcS for 12 wk in subjects with metabolic syndrome did not improve insulin sensitivity, beta-cell function, endothelial function, or inflammation markers in this trial.