A patient’s duodenal aspirate after a test meal shows low bicarbonate, low bile salts, but normal pancreatic enzyme concentrations. Predict the most likely pattern of nutrient absorption compared with normal:

• A. All macronutrients are absorbed at the same rate as normal because the small intestine rapidly synthesizes its own bicarbonate and bile salts to replace missing secretions on a minute-to-minute basis.
• B. Fat absorption increased dramatically because low bicarbonate enhances bile salt micelle stability and bile-independent passive diffusion becomes the dominant efficient pathway for lipid uptake.
• C. Protein absorption enhanced due to acidic activation of pancreatic proteases in the lumen combined with bile salt stimulation of peptide transporters in enterocytes, compensating for carbohydrate losses.
• D. Carbohydrate absorption nearly normal (amylase present), protein absorption moderately reduced if low pH inactivates proteases, and fat absorption markedly reduced because low bicarbonate inactivates lipase and low bile salts limit emulsification and micelle formation.

Answer: (D)