Digestive System
Your second brain. The digestive system is a 30-foot tube that breaks down food, absorbs nutrients, and eliminates waste. But it's much more— it houses 70% of your immune system and produces most of your serotonin. Gut health is total health.
Key Organs
Mouth
Digestion starts here. Chewing breaks food. Salivary amylase begins carb breakdown.
Stomach
Acid bath (pH 1.5-3.5). Protein digestion begins. Kills pathogens. Churns food.
Small Intestine
Main absorption site. 20 feet long. Villi increase surface area. Most nutrients absorbed here.
Large Intestine
Water absorption. Microbiome home. Stool formation. 5 feet long.
Liver
Makes bile. Processes nutrients. Detoxification. Largest internal organ.
Pancreas
Digestive enzymes. Bicarbonate to neutralize acid. Also makes insulin.
The Gut Microbiome
What It Is
Trillions of bacteria, fungi, viruses. More cells than human cells. 2-5 pounds of microbes.
Diversity Matters
More species = better health. Variety of fibers. Different fermented foods.
What They Do
Make vitamins, train immunity. Produce neurotransmitters. Digest fiber.
Short-Chain Fatty Acids
Butyrate, propionate, acetate. From fiber fermentation. Feed gut lining.
Gut-Brain Axis
Vagus nerve connection. Microbes affect mood. "Second brain" concept.
Dysbiosis
Imbalanced microbiome. Linked to many diseases. Antibiotics, diet, stress cause it.
Supporting Digestion
Chew Thoroughly
Digestion starts in mouth. 20-30 chews per bite. Signals stomach. Often overlooked.
Stomach Acid
Often too low, not too high. Apple cider vinegar, betaine HCl. Protein digestion needs acid.
Digestive Enzymes
Lipase, protease, amylase. Supplement if needed. With meals. Helps breakdown.
Bile Support
For fat digestion. Bitter foods stimulate. Ox bile supplements. Gallbladder function.
Fiber
Feeds microbiome. Both soluble and insoluble. 25-35g daily. Most don't get enough.
Probiotics
Beneficial bacteria. Fermented foods or supplements. Strain-specific benefits.
Common Digestive Issues
GERD/Reflux
Often low acid, not high. LES dysfunction. Diet, timing, weight matter.
IBS
Functional disorder. Gut-brain axis. Low FODMAP may help. Stress connection.
SIBO
Bacteria in wrong place. Bloating, malabsorption. Breath test diagnoses. Treat and prevent.
Leaky Gut
Intestinal permeability. Tight junctions open. Systemic inflammation. Heal the lining.
Constipation
Water, fiber, magnesium. Motility issues. Thyroid connection. Movement helps.
Food Intolerances
Not allergies. Enzyme deficiencies. Elimination diet identifies. Common: gluten, dairy.