Q) The principal energy source for colonocytes is:
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A. Glucose
B. Lactate
C. Butyrate
D. Long-chain fatty acids
✅ Answer: C. Butyrate
Butyrate is the primary fuel for colonocytes. It is a short-chain fatty acid (SCFA) produced by the colonic flora when fermenting complex carbohydrates. The colonic epithelium and luminal bacteria form a crucial symbiotic relationship where bacteria produce butyrate, which provides essential nutrition to the colonocytes.
Antibiotics disrupt this balance by reducing bacteria, leading to less butyrate, which negatively affects colonocyte function, often causing diarrhea.
🧠 Key Point: Butyrate, not glucose or lactate, is the key fuel for colonocytes, and its production relies on gut bacteria.
Teaching Points
- Short-chain fatty acids (SCFAs): butyrate, acetate, and propionate are produced by bacterial fermentation of dietary fiber.
- Butyrate provides ~70% of the energy requirements of colonocytes.
- It promotes mucosal integrity, anti-inflammatory effects, and epithelial repair.
- Reduced butyrate production is implicated in:
- Antibiotic-associated diarrhea
- Diversion colitis
- Inflammatory bowel disease
- High-fiber diets increase SCFA production and improve colonic health.
Why other options are incorrect
- A. Glucose — minimal utilization by colonocytes compared to SCFAs.
- B. Lactate — intermediate metabolite; not the primary fuel.
- D. Long-chain fatty acids — absorbed mainly in the small intestine.