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Biohydrogenation of cholesterol as an index of bacterial 7 alpha-dehydroxylase activity
Insights
Fecal steroid analysis reveals bacterial activity increases with age in children, approaching adult patterns. Gastrointestinal issues like shigellosis and castor oil challenge decrease this activity, while traveler
Area of Science:
- Gastroenterology
- Microbiology
- Biochemistry
Background:
- Fecal steroid composition reflects gut microbial activity.
- Bile acid and neutral sterol metabolism are influenced by age and health status.
Purpose of the Study:
- To investigate changes in fecal steroid composition across different age groups.
- To assess the impact of various gastrointestinal conditions on fecal steroid profiles.
- To explore the relationship between fecal steroids and bile acid metabolism.
Main Methods:
- Gas liquid chromatography was used to analyze fecal steroid compositions.
- 82 human subjects of diverse ages and gastrointestinal states were studied.
- Bacterial activities on bile acids and neutral sterols were quantified.
Main Results:
- Bacterial steroid metabolism increased with age in infants and children, reaching adult levels by age four.
- Acute shigellosis and castor oil administration reduced fecal steroid metabolism in adults.
- Traveler's diarrhea from toxigenic Escherichia coli did not significantly alter fecal steroid profiles.
- Strong negative correlations were found between 7α-dehydroxylation of cholic acid and fecal cholesterol (r = -0.921) and lithocholic acid production and fecal cholesterol (r = -0.739).
Conclusions:
- Fecal steroid analysis provides insights into age-related changes in gut microbial activity.
- Gastrointestinal infections and challenges significantly impact fecal steroid metabolism.
- Neutral steroid analysis serves as a reliable indicator of 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 activities 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 associated with toxigenic Escherichia 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 7 alpha-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 less than 0.001). The correlation between the production of lithocholic acid and the percentage cholesterol was also good (r = -0.739, p less than 0.001). Analysis of neutral steroids may be a good index of intraluminal bile acid metabolism.