Role of anaerobic bacteria in the metabolic welfare of the colonic mucosa in man.
Level 5 - mechanism / opinion, no new human data
Ex vivo physiological laboratory study using isolated human colonocytes
PubMed 7429343 · doi:10.1136/gut.21.9.793
What was done
Isolated epithelial cell suspensions (colonocytes) were prepared from human operative specimens of the ascending colon (n = 7) and descending colon (n = 7). Researchers measured respiration and the percentage of oxygen consumption attributable to physiological respiratory fuels: the short-chain fatty acid n-butyrate (produced by anaerobic bacteria) as well as glucose and glutamine, tested individually and in combination.
What was found
When n-butyrate was the sole substrate, it accounted for 73% of oxygen consumption in the ascending colon and 75% in the descending colon; with 10 mM glucose added, these proportions were 59% and 72%, respectively. Glucose oxidation alone accounted for 85% of oxygen consumption in the ascending colon but only 30% in the descending colon. In the presence of 10 mM n-butyrate, glucose oxidation dropped to 41% in the ascending colon and 16% in the descending colon. Aerobic glycolysis was detected in both regions.
Why it matters
This study provides foundational direct evidence that human colonocytes—particularly in the distal colon—preferentially utilize anaerobic bacterial fermentation products (n-butyrate) over circulating vascular glucose as their primary respiratory fuel.
Limits
The findings derive entirely from isolated cell suspensions in an ex vivo system, which may not fully mimic in vivo multi-substrate availability or intact tissue kinetics. The sample size was small (7 specimens per colonic site), and patient characteristics or underlying surgical indications were not reported in the abstract.
Cited by
- supports Butyrate is the primary metabolic fuel source for colonocytes.