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Biohydrogenation of cholesterol as an index of bacterial 7α-dehydroxylase activity
C T Huang1, M M Levine2, W E Woodward2
1Section of Nutrition and Gastroenterolory, Department of Pediatrics, Baylor College of Medicine, 77030, Houston, TX.
Insights
Fecal steroid analysis reveals significant age-related changes in gut bacteria
Area of Science:
- Microbiology
- Gastroenterology
- Biochemistry
Background:
- Gut microbiota plays a crucial role in metabolizing bile acids and neutral sterols.
- Age and gastrointestinal status significantly influence fecal steroid composition.
- Understanding these changes is vital for diagnosing and managing various gastrointestinal conditions.
Purpose of the Study:
- To investigate the impact of age and gastrointestinal status on fecal steroid profiles.
- To correlate specific fecal steroid transformations with host health conditions.
- To establish neutral steroid analysis as an indicator of bile acid metabolism.
Main Methods:
- Gas liquid chromatography was employed to analyze fecal steroid compositions.
- Data from 82 human subjects of diverse ages and health statuses were collected.
- Statistical analyses were performed to determine correlations between steroid ratios and clinical parameters.
Main Results:
- Bacterial activity on fecal steroids increases with age in infants and children, approaching adult patterns by age four.
- Adults with acute shigellosis or castor oil challenge showed decreased bacterial activity on fecal steroids.
- Traveller's diarrhea associated with toxigenic Escherichia coli did not significantly alter fecal steroid profiles.
- A strong positive correlation was found between 7α-dehydroxylation of cholic acid and fecal cholesterol percentage (r=0.921, p<0.001).
- A significant negative correlation was observed between lithocholic acid production and fecal cholesterol percentage (r=-0.739, p<0.001).
Conclusions:
- Fecal steroid profiles exhibit distinct developmental trajectories influenced by age.
- Gastrointestinal infections and challenges can alter fecal steroid metabolism.
- Neutral steroid analysis serves as a reliable index for assessing intraluminal bile acid metabolism.
Abstract:
Fecal steroid compositions of 82 human subjects of various ages and diets and gastrointestinal status were examined by gas liquid chromatography. Progressive increases in bacterial activities on both bile acids and neutral sterols were observed with the advance of age in infants and children. The patterns in the 4-year-olds approached those observed in adults. Bacterial activites on fecal steroids were found to be decreased in adult subjects with acute shigellosis and in those challenged by castor oil. In contrast, no significant changes in fecal steroid profiles were observed in the subjects with traveller's diarrhea assoicated with toxigenicEscherichia coli. The effects of diarrhea on fecal steroids of infants under 1(1/2) years were less consistent than those of adults. However, a close relationship was observed between the degree of 7α-dehydroxylation of cholic acid (expressed as the ratio of deoxycholic to the sum of deoxycholic and cholic acids) and the percentage of cholesterol in the feces (r= 0.921, p<0.001). The correlation between the production of lithocholic acid and the percentage cholesterol was also good (r=-0.739, p<0.001). Analysis of neutral steroids may be a good index of intraluminal bile acid metabolism.
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