Probiotics, prebiotics, synbiotics boost metabolism in NAFLD

Patients with nonalcoholic fatty liver disease (NAFLD) who take probiotics, prebiotics, or synbiotics (PPS) may have better energy metabolism, according to a recent study.

“The results showed that PPS regulation significantly improved the sugar and lipid metabolism indicators of NAFLD, and may have a negative impact on protein metabolism,” the researchers said.

“According to the results of this study, the PPS regulation method may reduce the levels of glucose, homeostatic model of insulin resistance, and insulin in NAFLD patients, and thus play a certain role in regulating the sugar metabolism level of patients,” they added.

A total of 29 randomized controlled trials were included in the meta-analysis, with a total cumulative sample of 2,110 NAFLD patients. Outcome measures included markers of energy metabolism, including glucose, insulin, total cholesterol, and high (HDL-C)- and low (LDL-C)-density lipoprotein cholesterol.

The Cochrane tool was used to assess the studies’ risk of bias. Papers were retrieved from the databases of CNKI, clinicaltrials.gov, PubMed, Embase, and the Cochrane Library.

Fifteen studies looked at the effect of PPS interventions on glucose. Pooled analysis revealed a significant decrease in these treatment arms as opposed to controls (standardized mean difference [SMD], –0.23, 95 percent confidence interval [CI], –0.45 to –0.01; p=0.04). [Front Public Health 2022;10:10:862266]

A similar effect was reported for insulin, as assessed by nine studies (SMD, –0.46, 95 percent CI, –0.76 to –0.16; p=0.002), and insulin resistance, according to eight studies (SMD, –0.47, 95 percent CI, –0.63 to –0.31; p<0.00001).

Moreover, the use of PPS led to significant improvements in lipid metabolism. This was characterized by a significant decrease in LDL-C (SMD, –0.57, 95 percent CI, –0.85 to –0.28; p<0.00001) and total cholesterol (SMD, –0.62, 95 percent CI, –0.87 to –0.36; p<0.00001) levels. No such impact, however, was reported for triglyceride (p=0.19) and HDL-C (p=0.95) concentrations.

The researchers also assessed the impact of the interventions on protein metabolism using the biomarker albumin. Pooled analysis of five studies showed a significant decrease in albumin (SMD, –0.34, 95 percent CI, –0.61 to –0.06; p=0.02) in the treatment arms vs controls.

“Considering the important role of intestinal microbiota in the process of protein synthesis and metabolism and the vital regulatory effect of microbial therapy on intestinal microbiota, PPS regulation may affect protein metabolism of NAFLD by regulating intestinal microbiota,” they said, adding that while PPS could be a potential treatment option for NAFLD, its effect on protein metabolism warrants further study and observation.

However, few studies have examined the interaction between microbial therapy and protein synthesis, and thus the present analysis is underpowered to draw strong conclusions on the matter.

Findings were robust to sensitivity analyses. Adjusting data processing according to preset indicators did not meaningfully change the obtained findings. In addition, funnel plots, qualified by Egger’s test, showed no publication bias.

Important study limitations include the small sample sizes of the included studies, some nonstandardized trial designs, and inconsistencies in bacterial strains and doses used. Further research is still needed to validate the PPS effects outlined in the present meta-analysis.