The Science of How Your Digestive System Actually Works
Most gut health content skips the basics. Before you can fix something, you need to understand how it works. This cluster covers the real mechanics of digestion, from stomach acid and bile acids to motility and enzymes, grounded in physiology research rather than wellness trends.
Current Consensus
- The migrating motor complex (MMC) is a cyclical pattern of smooth muscle contractions that sweeps residual material through the small intestine between meals.
- Stomach acid production is regulated by gastrin, histamine, and acetylcholine, and hypochlorhydria has multiple established causes including aging, H. pylori infection, and chronic PPI use.
- Bile acids function as signaling molecules beyond fat digestion, activating FXR and TGR5 receptors to regulate metabolism, inflammation, and gut motility.
- The enteric nervous system contains approximately 500 million neurons and can operate independently of the central nervous system.
- Digestive enzyme supplementation has strong evidence for exocrine pancreatic insufficiency but limited evidence for general supplementation in healthy individuals.
Open Questions
- How to reliably diagnose mild to moderate hypochlorhydria in clinical practice without invasive testing.
- The long-term effects of chronic PPI use on nutrient absorption and microbiome composition beyond currently documented associations.
- Whether bile acid malabsorption is a primary condition or secondary to other GI disorders in most patients.
- The optimal meal spacing interval for MMC activation across different populations and conditions.
- How the enteric nervous system adapts to chronic motility disorders over time.
Articles on How Digestion Actually Works and SIBO
Each article includes cited sources, a medical review placeholder, and a clear distinction between what is established and what is still being studied.
Bile Acids: The Unsung Regulators of Your Gut
Bile acids do far more than help you digest fat. They act as signaling molecules that regulate gut motility, metabolism, and the microbiome. Bile acid malabsorption is also a commonly missed cause of chronic diarrhea.
Digestive Enzymes: What Your Body Makes, What Supplements Add, and Whether You Need Them
Your body produces a full suite of digestive enzymes. Supplements are a massive market, but the evidence for using them outside of diagnosed insufficiency is thin. Here is what we actually know.
Gut Motility: Why Some People Are Fast, Some Are Slow, and What Controls the Speed
Gut motility determines how fast food moves through your digestive tract. The enteric nervous system, interstitial cells of Cajal, and serotonin all play critical roles, and when motility goes wrong, functional GI conditions follow.
The Migrating Motor Complex: Your Gut's Built-In Cleaning Crew
The migrating motor complex is a repeating wave of contractions that sweeps your small intestine between meals. Here is how it works, what disrupts it, and why it matters for bloating, SIBO, and motility.
Stomach Acid: What It Does, What Happens When You Don't Make Enough, and What the Claims Get Wrong
The real science of stomach acid production, hypochlorhydria, and why the baking soda test and apple cider vinegar trends do not hold up. What actually causes low stomach acid and when to see a doctor.
Medical Disclaimer: The content in this section is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional before making changes to your health regimen. GLP1Gut is a tracking tool, not a medical device.