Not medical advice. I am a software engineer, not a physician. This page documents my own protocol and the research I read while building it. Talk to a qualified clinician before changing your supplementation, diet or any treatment. Lab reference ranges quoted here vary by laboratory and by individual.
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The gastrointestinal tract is far more than a digestion tube. It houses approximately 70% of the immune system, contains over 500 million neurons (the enteric nervous system), and harbors roughly 38 trillion bacteria — a community collectively known as the gut microbiome. Disruptions to this ecosystem manifest not only as digestive symptoms (bloating, gas, reflux, constipation) but also as systemic issues: skin conditions, mood disorders, autoimmunity, and impaired nutrient absorption that undermines every other health goal.
Key insight: Gut health operates on three layers: (1) adequate digestive enzyme and acid production to break food down, (2) an intact intestinal barrier to prevent undigested proteins and endotoxins from entering the bloodstream, and (3) a diverse, balanced microbiome to regulate immunity and produce essential metabolites like short-chain fatty acids.
Digestion begins in the stomach, where hydrochloric acid (HCl) activates pepsinogen into pepsin for protein breakdown and kills ingested pathogens. Stomach acid production declines with age: by 60, many people produce 25–35% less HCl than at 25. Low stomach acid (hypochlorhydria) causes incomplete protein digestion, poor mineral absorption (especially iron, calcium, magnesium), and bacterial overgrowth in the small intestine (SIBO). Betaine HCl supplementation restores acid levels, while comprehensive enzyme blends (protease, lipase, amylase, cellulase) ensure complete macronutrient breakdown in the duodenum.
The intestinal lining is a single layer of epithelial cells held together by tight junction proteins (claudins, occludin, zonulin). When these junctions loosen — due to chronic stress, NSAIDs, alcohol, processed food, or dysbiosis — the barrier becomes permeable ("leaky gut"), allowing lipopolysaccharides (LPS) and food antigens to enter systemic circulation and trigger low-grade chronic inflammation. L-Glutamine is the primary fuel source for enterocytes (intestinal epithelial cells). A landmark study by Rao and Samak (2012) demonstrated that glutamine supplementation preserves tight junction integrity and reduces intestinal permeability under stress conditions.
Rao, R. K., & Samak, G. (2012). Role of glutamine in protection of intestinal epithelial tight junctions. J Epithel Biol Pharmacol, 5(Suppl 1-M7), 47-54. PMID: 28440323
The gut microbiome is a metabolically active organ. Beneficial bacteria (Lactobacillus, Bifidobacterium) produce short-chain fatty acids (SCFAs) — butyrate, propionate, acetate — that nourish colonocytes, regulate immune tolerance, and maintain barrier integrity. Probiotic supplementation introduces beneficial strains, while prebiotic fibers (inulin, FOS, beta-glucan) selectively feed them. Oat fiber is particularly valuable as a source of beta-glucan, which is fermented into butyrate by colonic bacteria. Berberine, a plant alkaloid, has demonstrated antimicrobial properties against pathogenic bacteria while sparing beneficial strains, making it useful for rebalancing a dysbiotic gut.
Hill, C., et al. (2014). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol, 11(8), 506-514. PMID: 24912386
The following supplements address all three layers of gut health: enzymatic digestion, barrier repair, and microbiome support. For full dosing and timing details, see the Supplement Stack article.
| Supplement | Role | Timing | Link |
|---|---|---|---|
| Super Enzymes | Broad-spectrum enzyme blend (protease, lipase, amylase) for complete macronutrient breakdown | With meals (lunch & dinner) | Stack → |
| Multi Enzymes | Plant-based enzyme complex for carbohydrate and fiber digestion | With meals | Stack → |
| Betaine HCl | Restores stomach acid for protein digestion and mineral absorption | With protein-rich meals | Stack → |
| L-Glutamine | Primary fuel for enterocytes, repairs tight junctions, reduces permeability | Fasted (AM) or between meals | Stack → |
| Probiotics | Introduces beneficial Lactobacillus and Bifidobacterium strains | With breakfast | Stack → |
| Prebiotic Fiber (inulin/FOS) | Selectively feeds Bifidobacterium and promotes SCFA production | With breakfast or dinner | Stack → |
| Oat Fiber | Beta-glucan source, fermented into butyrate by colonic bacteria | With breakfast | Stack → |
| Berberine | Antimicrobial against pathogenic bacteria, supports microbiome rebalancing | With meals (2–3x/day) | Stack → |
Betaine HCl caution: Do not take Betaine HCl if you have active gastric ulcers or are taking NSAIDs. Start with one capsule per protein-rich meal and increase gradually. A warm/burning sensation indicates you have exceeded your dose — reduce by one capsule.
Roberfroid, M., et al. (2010). Prebiotic effects: metabolic and health benefits. Br J Nutr, 104(Suppl 2), S1-S63. PMID: 20695770
Gut dysfunction often hides behind nonspecific symptoms. These lab tests help identify inflammation, malabsorption, and systemic effects of poor gut health. See the Preventive Lab Tests guide for reference ranges and ordering details.
| Test | What It Measures | Frequency | Link |
|---|---|---|---|
| CRP (C-Reactive Protein) | Systemic inflammation marker — elevated CRP may indicate gut-driven immune activation and increased intestinal permeability | Every 6 months | Details → |
| Urinalysis | Screens for urinary tract health, protein leakage, and pH — indirect marker of systemic acid-base balance influenced by gut function | Annually | Details → |
| Vitamin B12 | Absorption marker — B12 requires intrinsic factor and adequate stomach acid for absorption; low levels suggest hypochlorhydria or ileal dysfunction | Annually | Details → |
| Iron Panel (serum iron, TIBC, ferritin, saturation) | Iron absorption depends on stomach acid and duodenal health; low iron despite adequate intake suggests malabsorption | Every 6 months | Details → |
The B12–iron connection: If both B12 and iron are low despite adequate dietary intake, the most likely culprit is impaired stomach acid production. Betaine HCl and digestive enzymes often resolve both deficiencies by restoring proper digestion and absorption.
A December 2025 Harvard study published in Cell Metabolism discovered that certain molecules produced by gut bacteria travel to the liver and directly regulate energy metabolism, with these metabolites varying based on diet, genetics, and microbiome composition. Separately, University of Utah researchers identified Turicibacter, a specific gut bacterium that improves metabolic health and reduces weight gain on high-fat diets; people with obesity tend to have less Turicibacter. Large-scale shotgun metagenomic studies (2025-2026) have identified a reproducible type 2 diabetes-associated microbiome signature characterized by depletion of short-chain fatty acid-producing taxa and enrichment of pro-inflammatory opportunistic microorganisms.
Emerging research in 2026 on gut microbiota circadian rhythms shows that gut bacteria exhibit robust circadian oscillations synchronized with host metabolic cycles. Disruption of these microbial rhythms (from irregular meal timing, shift work, or jet lag) is increasingly recognized as a contributor to obesity and metabolic syndrome, adding "when you eat" to the list of factors influencing gut health alongside "what you eat."
ScienceDaily (2025). Harvard gut discovery could change how we treat obesity and diabetes. ScienceDaily