Fasting and refeeding triggers specific changes in bile acid profiles and gut microbiota.
Level 5 - mechanism / opinion, no new human data
Animal research with no human data
PubMed 36682739 · doi:10.1111/1753-0407.13356
What was done
Mice were divided into three feeding conditions: fed ad libitum, fasted for 24 hours, or fasted for 24 hours and then refed for 24 hours. Bile acid profiles in plasma, feces, and liver were measured using ultraperformance liquid chromatography coupled to tandem mass spectrometry. Gut microbiota composition was analyzed via 16S rRNA gene sequencing. Expression of hepatic bile acid biosynthesis-related genes and ileal bile acid reabsorption-related genes was also measured.
What was found
The abstract reports directional changes without numerical values, confidence intervals, or p-values. In fasted mice compared with controls, unconjugated primary and secondary bile acids in plasma decreased, while plasma conjugated secondary bile acids, fecal unconjugated and conjugated bile acids, and liver unconjugated secondary bile acids increased. Expression of hepatic bile acid biosynthesis genes and ileal reabsorption genes decreased during fasting. Fasting increased Akkermansia, Parabacteroides, Muribaculum, Eubacterium coprostanoligenes, and Muribaculaceae, while decreasing Lactobacillus and Bifidobacterium. All bile acid, gene expression, and microbial shifts reversed after 24 hours of refeeding. Akkermansia abundance was negatively correlated with plasma unconjugated bile acids and glucose, and positively correlated with plasma conjugated secondary bile acids and fecal unconjugated bile acids.
Why it matters
The study shows that nutrient availability rapidly and reversibly remodels systemic bile acid distribution, host metabolic gene expression, and gut microbial structure.
Limits
The abstract provides no sample size, effect sizes, variance measures, or specific statistical test values. The study was conducted exclusively in a rodent model, limiting direct translation to human fasting physiology. Specific genes assayed for biosynthesis and reabsorption were not identified in the abstract.
Cited by
- supports A Nature paper showed that during fasting, the gut microbiome more actively converts bile into beneficial signaling molecules and short-chain fatty acids.