Digestive Health and the Gut Microbiome
What the exam tests
This domain covers digestive physiology, enzyme and acid function, motility, the gut microbiome, dysbiosis, food intolerances, low-FODMAP nutrition, and the gut-brain axis.
Core rules
- Digestion begins with cephalic-phase signals; gastric acid and pepsin start protein breakdown; pancreatic enzymes and bile complete fat, protein, and carbohydrate digestion; brush-border enzymes finish disaccharide digestion.
- The colon ferments fiber and resistant starch into short-chain fatty acids, especially butyrate, which nourish colonocytes.
- Microbiome diversity is associated with fiber variety, fermented foods, and plant exposure; probiotic effects are strain-specific.
- Low-FODMAP is a three-phase protocol: restriction, reintroduction, and personalization; it is not a permanent diet.
- Red flags for referral include unintentional weight loss, anemia, blood in stool, persistent vomiting, and new symptoms after age 50.
Worked example
A client reports bloating and gas after meals. Reasoning: clarify timing (immediate versus 30-90 minutes), stool pattern, recent antibiotics, diet recall, and red flags. If symptoms are consistent with fermentable carbohydrate intolerance, a structured low-FODMAP trial with a qualified dietitian and symptom diary is reasonable, followed by reintroduction to identify triggers. Do not label it "candida" without evidence.
Traps
- Treating every digestive symptom as dysbiosis.
- Keeping clients on low-FODMAP indefinitely.
- Recommending probiotics without matching strain and indication.
- Missing red flags that require medical care.