Adherence to a freshwater fish-based diet helps regulate gut microbiota and its metabolites, suggesting benefits in people with non-alcoholic fatty liver disease (NAFLD), a study finds.
On the other hand, consuming a similar total of animal protein and fat from alternating freshwater fish and red meat does not appear to be dangerous in the dietary management of NAFLD patients.
“[T]his 84-day randomized controlled pilot study in participants with NAFLD showed that the freshwater fish diet induced greater improvement in fatty liver disease and other metabolic phenotypes by regulating the gut microbiota and its metabolites compared to alternating freshwater fish and red meat based diet, independent of weight change,” the researchers said.
Using computer-generated random number assignment by a researcher not involved in this study, 34 NAFLD patients with fatty liver disease ≥10% were randomized to the fish group (F) or the fish and meat group (F/M) alternately. The fat content of the liver and the intestinal microbiota and its metabolites were then measured.
Patients in group F had a significantly greater absolute reduction in hepatic steatosis at the end of the intervention than those in group F/M (‒4.89% vs. ‒1.83%; p=0.032). [Am J Gastroenterol 2022;117:1621-1631]
Sixteen secondary endpoints were also assessed: body weight, waist circumference, body mass index, fasting blood glucose, fasting insulin, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase, total cholesterol, low density lipoprotein cholesterol , high density lipoproteins cholesterol, triglycerides, interleukin-6, tumor necrosis factor-α, C-reactive protein and ferritin.
Of these, seven improved in the F group, including alanine aminotransferase and gamma-glutamyl transferase, which was higher than in the F/M group. Notably, alternating consumption of freshwater fish and red meat in the diet did not worsen NAFLD.
Additionally, significantly greater changes in Faecalibacterium, short-chain fatty acid, and unconjugated bile acid enrichment and depletion of
Prévotelle 9 and conjugated bile acids were noted in group F versus group F/M.
A growing body of evidence suggests the important role played by the gut microbiota in the onset and development of diabetes, obesity, cardiovascular disease and NAFLD. [Nature 2012;490:55-60]
“Therefore, we explored the potential involvement of the gut microbiota in mediating the enhancement of NAFLD induced by dietary freshwater fish. In group F, the abundance of
Faecalibacterium increased as the abundance of Escherichia Shigella and
Prévotelle 9 decreased at the end of the intervention,” the researchers said.
“However, these results should be considered preliminary and large-scale controlled studies are needed to confirm these results,” they noted.
Besides the gut microbiota, several metabolites produced by commensal bacteria have been suggested to influence the pathogenesis and progression of NAFLD. [Gut 2019;68:359-370]
“Gut macrobiotic-related metabolites, including short-chain fatty acids (SCFAs), amino acid catabolites, and butyric acids (Bas), regulate fatty liver and inflammation by signaling from their homologous receptors “, said the researchers. “We therefore attempted to clarify the metabolites (i.e. SCFAs and BAs) that potentially mediate the beneficial impact of dietary freshwater fish consumption on NAFLD.”