Clinical Nutritionist CCN Gastrointestinal Health and Nutrition 2 — Questions and Answers
Question 1: Which enzyme initiates carbohydrate digestion in the oral cavity?
- Pepsin
- Pancreatic lipase
- Salivary amylase (Correct answer)
- Sucrase
Correct answer: Salivary amylase
Salivary amylase (ptyalin) cleaves alpha-1,4 glycosidic bonds in starch, beginning carbohydrate digestion before food reaches the stomach.
Question 2: Achlorhydria (absent stomach acid) most significantly impairs absorption of which nutrients?
- Fat-soluble vitamins A, D, E, K
- Iron and vitamin B12 (Correct answer)
- Calcium and phosphorus
- Water-soluble vitamins C and folate
Correct answer: Iron and vitamin B12
Gastric acid is required to reduce dietary iron from Fe3+ to the absorbable Fe2+ form and to release protein-bound B12 from food.
Question 3: The migrating motor complex (MMC) serves primarily as the intestinal 'housekeeper' by:
- Mixing chyme with digestive enzymes during meals
- Absorbing electrolytes from digested food
- Sweeping bacteria and undigested debris through the gut between meals (Correct answer)
- Regulating bile release from the gallbladder
Correct answer: Sweeping bacteria and undigested debris through the gut between meals
The MMC, which occurs during fasting, generates peristaltic waves that clear bacteria and debris from the small intestine, preventing bacterial overgrowth.
Question 4: The low-FODMAP diet is considered the most evidence-based dietary intervention for managing:
- Celiac disease
- Irritable bowel syndrome (IBS) (Correct answer)
- Crohn's disease
- Gastroparesis
Correct answer: Irritable bowel syndrome (IBS)
Multiple randomized controlled trials demonstrate that the low-FODMAP diet reduces IBS symptoms in approximately 50–75% of patients by limiting fermentable carbohydrates.
Question 5: Secretory IgA (sIgA) in the gut primarily functions to:
- Trigger inflammatory cytokine cascades
- Activate the complement system against bacteria
- Neutralize pathogens and prevent their adherence to intestinal mucosa (Correct answer)
- Directly lyse bacterial cell walls
Correct answer: Neutralize pathogens and prevent their adherence to intestinal mucosa
sIgA is the dominant mucosal antibody; it coats pathogens and toxins, preventing their adherence to the epithelium without inducing inflammation.
Question 6: Vitamin D deficiency is most prevalent among patients with inflammatory bowel disease (IBD) because of:
- Reduced dietary intake of fortified foods only
- Combination of malabsorption, reduced sun exposure, and chronic inflammation (Correct answer)
- Increased renal excretion caused by corticosteroid use
- Competitive inhibition by calcium supplementation
Correct answer: Combination of malabsorption, reduced sun exposure, and chronic inflammation
IBD patients suffer vitamin D deficiency through multiple mechanisms: fat malabsorption reduces uptake, illness limits outdoor activity, and inflammation alters vitamin D metabolism.
Question 7: Butyrate exerts its primary anti-inflammatory effect in colonocytes by:
- Stimulating NF-kB signaling pathways
- Activating pro-inflammatory cytokine release
- Inhibiting histone deacetylase (HDAC) enzymes (Correct answer)
- Reducing intestinal blood flow
Correct answer: Inhibiting histone deacetylase (HDAC) enzymes
Butyrate inhibits HDAC, an epigenetic mechanism that suppresses inflammatory gene transcription and promotes regulatory T-cell differentiation.
Clinical Nutritionist CCN Gastrointestinal Health and Nutrition 2
Which enzyme initiates carbohydrate digestion in the oral cavity?