Why is fat digestion considered limited in the mouth and stomach compared with the small intestine?

• A. Because lingual and gastric lipases denature at neutral pH encountered in the small intestine, so they are only active after bile salts decrease the pH again to re-activate them.
• B. Because the stomach actively absorbs most fatty acids there, leaving little substrate for intestinal digestion; the small intestine is primarily responsible for water and electrolyte handling rather than lipid processing.
• C. Because mechanical peristalsis in the stomach completely prevents enzyme–substrate contact for lipases, and pancreatic enzymes are synthesized in the mouth to be delivered via saliva later into the colon.
• D. Because lingual and gastric lipases contribute only modest hydrolysis and effective large-droplet emulsification requires bile released into the small intestine for pancreatic lipases to access substrates efficiently.

Answer: (D)