GI Nutrition & Gut Health 2 — Questions and Answers
Question 1: Which short-chain fatty acid produced by gut bacteria is the primary energy source for colonocytes?
- Acetate
- Propionate
- Butyrate (Correct answer)
- Succinate
Correct answer: Butyrate
Butyrate is the preferred energy substrate for colonocytes and plays a key role in maintaining colonic mucosal integrity.
Question 2: A patient with celiac disease must avoid which protein found in wheat, barley, and rye?
- Casein
- Gluten (Correct answer)
- Lactalbumin
- Zein
Correct answer: Gluten
Gluten triggers an immune-mediated inflammatory response in the small intestinal mucosa of celiac disease patients.
Question 3: What is the recommended daily fiber intake for adults according to the Dietary Guidelines for Americans?
- 10–15 grams
- 20–25 grams
- 25–38 grams (Correct answer)
- 45–55 grams
Correct answer: 25–38 grams
The Dietary Guidelines recommend 25 g/day for women and 38 g/day for men, with a general target of 25–38 g/day.
Question 4: Which vitamin requires intrinsic factor secreted by gastric parietal cells for intestinal absorption?
- Vitamin B6
- Vitamin B12 (Correct answer)
- Folate
- Vitamin C
Correct answer: Vitamin B12
Intrinsic factor binds vitamin B12 in the stomach, and the complex is absorbed in the terminal ileum.
Question 5: Lactase deficiency leading to lactose intolerance causes GI symptoms primarily through which mechanism?
- Mucosal inflammation
- Osmotic diarrhea and gas from bacterial fermentation (Correct answer)
- Increased gastric acid secretion
- Delayed gastric emptying
Correct answer: Osmotic diarrhea and gas from bacterial fermentation
Undigested lactose draws water into the colon osmotically and is fermented by bacteria, producing gas, bloating, and diarrhea.
Question 6: Which type of dietary fiber is most effective at lowering LDL cholesterol by binding bile acids in the gut?
- Insoluble fiber (cellulose)
- Soluble fiber (beta-glucan, psyllium) (Correct answer)
- Resistant starch
- Lignin
Correct answer: Soluble fiber (beta-glucan, psyllium)
Soluble fiber forms a viscous gel that binds bile acids, preventing their reabsorption and promoting cholesterol conversion to new bile acids.
Question 7: A patient on long-term proton pump inhibitor (PPI) therapy is at increased risk for deficiency of which nutrient?
- Vitamin A
- Calcium and magnesium (Correct answer)
- Vitamin K
- Zinc
Correct answer: Calcium and magnesium
Long-term PPI use reduces gastric acid needed for calcium and magnesium absorption, increasing fracture and hypomagnesemia risk.
GI Nutrition & Gut Health 2
Which short-chain fatty acid produced by gut bacteria is the primary energy source for colonocytes?