A metabolite study demonstrated that indolepropionate was only detectable in the plasma of conventionally housed mice and not germ-free mice.18 One known function of indolepropionate is its ability to bind and activate Pregnane X receptor (PXR) which leads to improved intestinal barrier function and reduction of enterocyte tumor necrosis factor-α (TNF-α), two features that are abnormal in patients with NAFLD.42 Additionally, indolepropionate has strong correlations with human obesity and fatty liver disease. This evidence concerns the gene NR1I2 and obesity due to melanocortin 4 receptor deficiency.