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Prebiotics and Probiotics in Nonalcoholic Fatty Liver Disease

3/26/2019 11:15:46 AM

kimchiInflammation, microbiome balance tightly connected with liver health

Nonalcoholic fatty liver disease (NAFLD), the hepatic manifestation of metabolic syndrome, can progress to steatohepatitis (NASH), hepatic fibrosis, and liver failure. Along with the classic components of metabolic syndrome, the intestinal microbiome might also influence the pathogenesis of NAFLD. Increased intestinal inflammation and permeability are thought to allow the translocation of bacteria and bacterial-derived endotoxins, which stimulate an inflammatory cascade in hepatic tissue.

Microbial therapies, probiotics studied for potential to benefit liver

Microbial therapies that have been evaluated in patients with NAFLD include prebiotics (nondigestible starches that promote the growth of beneficial microorganisms), probiotics (live microorganisms), and synbiotics (a combination of both). It is thought that these microbial therapies might benefit NAFLD by limiting the proliferation of pathogens, modulating immune responses, and supporting intestinal health. To assess the available evidence for the role of microbial therapies in NAFLD, researchers conducted a systematic review and meta-analysis.
The meta-analysis included 25 studies, involving 1309 patients (59% men and 41% women). All of the studies were randomized, placebo-controlled trials of microbial therapies in patients with NAFLD, steatosis, liver fibrosis, or steatohepatitis. Study durations ranged from 2 weeks to 7 months. Prebiotic treatments included beta-glucan, psyllium husk, fructooligosaccharides (FOS), chicory inulin, and fiber extracts. Probiotic treatments included many different species, with Lactobacillus acidophilus being the most common and most studies supplementing multiple organisms. Synbiotics combined probiotics with FOS or inulin.

Microbial therapies aid weight management, liver enzyme levels

Analysis of the 3 treatment groups combined showed that microbial therapy significantly reduced body mass index (BMI) by a mean of 0.37 kg/m2, reduced alanine transaminase (ALT) by 6.85 U/L, reduced aspartate transaminase (AST) by 4.64 U/L, and reduced gamma-glutamyl transferase (GGT) by 7.86 U/L. Marginal decreases were observed for tumor necrosis factor-alpha (TNF-alpha) and hepatic cytokine c-reactive protein (CRP), but both failed to reach statistical significance.   
For lipid profiles, analysis of the 3 treatment groups combined showed that microbial therapy significantly reduced total cholesterol (TC) by 10.10 mg/dL, reduced low-density lipoprotein cholesterol (LDL-C) by 4.52 mg/dL, and reduced triglycerides (TG) by 10.14 mg/dL. Microbial therapy did not affect high-density lipoprotein cholesterol (HDL-C). 
Probiotics help manage BMI
Subgroup analyses found that prebiotics, probiotics, and synbiotics had similar effects on the outcomes described above (BMI, liver enzymes, inflammatory markers, and lipids) with a few exceptions. Synbiotics did not affect ALT, only synbiotics (but not prebiotics or probiotics) reduced TC, and only prebiotics (but not probiotics or synbiotics) reduced LDL-C.
Because of the limited number of studies and the wide variety of protocols used, it is not possible to draw conclusions about dosage, duration, or the type of microbial therapy that is most effective in patients with NAFLD. More research is needed, but the results of this meta-analysis show promise for a role of microbial therapy in NAFLD.
Loman BR, Hernández-Saavedra D, An R, Rector RS. Prebiotic and probiotic treatment of nonalcoholic fatty liver disease: a systematic review and meta-analysis. Nutr Rev. 2018; 76: 822-839.

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