Science Update

New review demonstrates the role of the gut microbiome and probiotics in nonalcoholic fatty liver disease

A couple weeks ago we examined the role of probiotics via the gut-liver axis in nonalcoholic fatty liver disease (NAFLD). Now, let’s explore this a bit more by looking at a new review just published in Nutrients, where researchers investigated the role of the gut microbiome and probiotics in NAFLD.

This review included 26 major randomized controlled trials using probiotics or synbiotics for NALFD/NASH (non-alcoholic steatohepatitis). These studies ranged from 20 to 200 individuals carried out over a period from 4 weeks to 1 year. Laboratory assessments included liver enzymes and anthropometric parameters. Some of the studies included cardiovascular risk factors such as C-reactive protein and lipid profiles as well as markers of insulin resistance. Most of the studies used probiotic formulations including multiple species; however, a few were conducted using a single strain.

In general, probiotic supplementation demonstrated a significant decrease in liver enzymes compared to placebo groups. In addition, probiotics were also shown to have a synergistic effect with metformin on liver enzymes in patients with NASH. Products that contained both prebiotics and probiotics demonstrated a similar effect as seen in the probiotic groups. On the other hand, one study showed a reduction in intrahepatic fat measured by MRI, but the improvement in liver enzymes did not reach clinical significance. It is important to note that liver enzymes can have high variability and do not always directly correlate with disease progression.

Five meta-analyses were also included in this review, all demonstrating that probiotics and synbiotics had a significant improvement on AST and ALT levels.

Several other studies have assessed probiotics with hepatic steatosis, fibrosis, and liver stiffness. Ultrasound imaging assessing these parameters have shown positive clinical outcomes with probiotics and synbiotics. There has also been some novel MRI testing that has demonstrated similar beneficial effects of probiotic supplementation.

Probiotics restore the gastrointestinal barrier function, modulate the immune system, and inhibit the proliferation of harmful bacteria. They have been shown to help reduce liver fat and improve liver enzymes. Probiotics are likely most effective by helping to prevent bacterial translocation and reducing the effects of the intestinal microbiota on the liver.

Individuals with NAFLD have established disease and higher nutrient demands than what could be obtained from the diet alone and, therefore, dietary supplements should be considered to help reduce the progression of the disease and improve liver function. Other nutrients to consider include delta and gamma tocotrienols, fish oil, coenzyme Q10, berberine, and milk thistle.

By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS

Source: Xie C and Halegoua-DeMarzio D. Role of Probiotics in Non-alcoholic Fatty Liver Disease: Does Gut Microbiotia Matter? Nutrients. 19 November 2019, 11(11), 2837.