Mucosal atrophy that accompanies bowel rest may result from the absence of which nutrient?

• A. Short-chain fatty acids
• B. Glutamine
• C. Glucose
• D. L-cysteine

Answer: (B)

Glutamine is the primary fuel for enterocytes and is essential for maintaining gut mucosal structure and function. When bowel rest occurs, luminal nutrients are withheld, and enterocytes rely on glutamine for energy to support cell proliferation and barrier integrity. Without adequate glutamine, the mucosa undergoes atrophy as the cells lose their energy source and regenerative capacity. Short-chain fatty acids help colonocytes but depend on luminal substrates and aren’t the direct driver of small-intestinal mucosal maintenance in bowel rest. Glucose provides general energy but isn’t specifically tied to preventing mucosal atrophy, and L-cysteine isn’t the key energy source for mucosal cells.