Gut Health — Intermediate Guide

Intermediate Gut Health

Digestive System Fundamentals

DIGESTION STEP BY STEP:
  Mouth: chewing + amylase (starts starch digestion)
         Tip: chew 20–30 times per bite — aids entire digestion
  
  Stomach: HCl (pH 1.5–3.5) + pepsin (protein digestion)
            Churning for 2–4 hours → chyme
            Acid sterilises food, activates enzymes
  
  Small intestine (6–7 metres):
    Duodenum: pancreatic enzymes + bile emulsify fats
    Jejunum: primary nutrient absorption
    Ileum: B12 and bile acid absorption
    Villi + microvilli: massive surface area = ~250 sqm
  
  Large intestine (colon, 1.5 metres):
    Water absorption
    Bacterial fermentation of undigested fibre
    Short-chain fatty acid production
    Formation and storage of faeces

COMMON DIGESTIVE DISORDERS:

  IBS (Irritable Bowel Syndrome):
    Functional disorder — no structural damage
    Subtypes: IBS-C (constipation), IBS-D (diarrhoea), IBS-M (mixed)
    Triggers: stress, certain foods (FODMAPs), hormonal changes
    Affects ~15% of global population
  
  GERD (Acid Reflux):
    Lower oesophageal sphincter weakness → acid reflux
    Triggers: large meals, lying down after eating, obesity, caffeine, alcohol
    Management: elevate head of bed, small frequent meals, avoid triggers
  
  Constipation:
    <3 bowel movements/week, hard stools, straining
    Causes: low fibre, dehydration, sedentary, medications (iron, opioids)
    Management: increase fibre gradually, hydration, activity, squat position

TIPS FOR BETTER DIGESTION:
  Eat slowly — 20 minutes for satiety signals
  Stay upright 2–3 hours after eating
  Warm water/herbal tea aids motility
  Exercise regularly — improves gut transit
  Manage stress — gut-brain axis is real
  Sleep 7–9 hours — gut microbiome follows circadian rhythm

Revision Notes

DIGESTION ORDER: mouth (amylase) → stomach (HCl+pepsin) → small intestine (absorb) → colon (ferment)
STOMACH: pH 1.5-3.5 | sterilises food | activates pepsin | 2-4hr retention
SMALL INTESTINE: primary absorption | 250sqm surface area via villi
COLON: water absorption + fibre fermentation + SCFA production
IBS: functional | no damage | triggers: stress/FODMAPs | 15% population
GERD: LES weakness | small meals | upright after eating | elevate head