Central Theory of UC/Proctitis

This page is the evolving causal model for Paul’s UC/proctitis. It should be updated every time we digest sources. The goal is not to defend one pet theory; the goal is to converge on a practical, testable explanation of why the disease happens, why it starts distally, why Paul’s pattern begins with mucus/constipation, and what levers could plausibly produce durable healing/remission.

Concise running takeaways are maintained in Proctitis. The highest-signal findings are maintained in Proctitis. The highest-priority unresolved questions are maintained in Proctitis. Every major digest should promote durable insights to key-insights.md, strongest numerical/mechanistic findings to top-research-insights.md, and newly sharpened unresolved questions to key-open-questions.md with source links and evidence labels.

Working thesis v1.4

Paul’s UC/proctitis may be best modeled as a local distal mucus-barrier + epithelial energy/redox + microbial ecology failure that becomes self-reinforcing through immune activation, motility changes, and systemic liver/lipid inflammation — rather than as a purely abstract autoimmune attack.

After UC Causal Mechanism Digest 001, UC Causal Mechanism Digest 002, UC Causal Mechanism Digest 003, UC Causal Mechanism Digest 004, UC Causal Mechanism Digest 005, and UC Causal Mechanism Digest 006, UC Causal Mechanism Digest 007, UC Causal Mechanism Digest 008, UC Causal Mechanism Digest 009, UC Causal Mechanism Digest 010, UC Causal Mechanism Digest 011, UC Central Theory Scite Validation Pass, and Non-IgE Dairy Hypersensitivity Digest, the leading causal nodes are:

1. Mucus phosphatidylcholine/barrier failure — PC-rich mucus appears central to keeping microbiota away from mucosa; UC may involve low mucus PC and impaired transport. This is a core causal candidate, but PC intervention evidence is formulation-specific and now mixed after negative/mixed LT-02 trials.
2. Colonocyte mitochondrial energy/redox vulnerability — UC biopsies show marked impairment of mitochondrial acetoacetyl-CoA thiolase and increased hydrogen peroxide formation, suggesting a reversible redox-linked butyrate-oxidation bottleneck may be central.
3. Microbial niche/pathobiont positioning — disease may depend not only on which microbes exist, but whether pathobionts, toxins, mucolytic organisms, sulfide producers, or otherwise ordinary commensals cross from lumen/outer mucus into inner mucus, epithelial surface, crypts, or tissue. Digest 009 elevated microbial location/virulence factors over generic stool microbiome labels.
4. Beneficial commensal/butyrate ecology — reduced or functionally weakened Faecalibacterium prausnitzii, Roseburia hominis, and related butyrate-supporting ecology may lower colonocyte fuel, anti-inflammatory signaling, mucus/barrier reserve, and resistance to pathobionts; specific probiotic/fiber interventions are promising but strain/formulation/tolerance-specific.
5. Distal exposure/contact-time/pelvic-floor amplification — the rectum/distal colon appears to be a high-contact, relative-stasis, low-reserve mucus-barrier zone; UC-associated constipation, stool retention, tenesmus, and incomplete evacuation could explain why Paul’s symptoms start with mucus/constipation and why UC often begins as proctitis. Digest 011 sharpened the intervention logic: support butyrate ecology only if the method also reduces contact time, straining, and incomplete evacuation.
6. Food-trigger threshold events — dairy/milk protein/lactose and gluten/wheat/fructans may not be universal UC root causes, but they can plausibly trigger or amplify inflammation when Paul’s rectal barrier reserve is low. The 2026-06-28 milk/oral-tolerance digest refines this as milk-triggered loss-of-tolerance / barrier-threshold amplification rather than a simple “milk allergy caused UC” claim.
7. Sleep/apnea/circadian threshold control — poor sleep, sleep apnea, intermittent hypoxia, and circadian disruption may lower barrier resilience through cytokines, permeability, dysbiosis, motility/autonomic changes, and impaired repair.
8. Gut-liver-lipid/ALP axis — Paul’s cholesterol/ALP patterns are an objective biomarker branch; ALP must be split by source/fraction and lipids must be interpreted against a population literature that often shows lower lipids with active IBD.

In this model, the rectum/distal colon becomes vulnerable when several factors stack:

1. Barrier/mucus layer vulnerability — mucus depletion, goblet-cell stress, phosphatidylcholine deficiency, epithelial energy problems, or impaired repair.
2. Local microbial/metabolite pressure — dysbiosis/pathobionts, hydrogen sulfide/nitric oxide/redox stress, bile acids, ammonia/phenols, fermentation changes, or infection history.
3. Stool retention/contact-time amplification — constipation or incomplete evacuation keeps irritants in contact with the distal mucosa, explaining why symptoms can begin with mucus and constipation rather than diarrhea.
4. Food-trigger amplification — dairy and possibly gluten/wheat may trigger rapid local inflammation through immune reactivity, fermentation, histamine/mast-cell activation, sulfur/metabolite shifts, or microbiome effects.
5. Stress/sleep/autonomic amplification — stress, poor sleep, and sleep apnea may weaken barrier repair, alter motility, increase sympathetic tone, and increase inflammatory signaling.
6. Systemic liver-lipid-bile axis response — cholesterol and ALP changes during flares may reflect gut-liver signaling, endotoxin/leaky-gut effects, bile flow, hepatic inflammation, bone/liver ALP fraction issues, or an IBD-associated biliary process.

This theory should remain explicitly testable and revise as evidence accumulates.

Scite validation status — 2026-06-27

The scite validation pass strengthened the current model rather than overturning it. The most strongly validated pieces are the MUC2 inner-mucus spatial barrier model, active UC mucus penetrability, UCAC/contact-time mechanics, sleep/circadian barrier-threshold effects, and the beneficial-commensal/butyrate branch.

Key refinements from scite:

• Functional microenvironment > generic microbiome labels. Future microbiome interpretation should ask whether the distal lumen/mucus environment has lower H₂S/indole/protein fermentation pressure, adequate SCFA/butyrate ecology, intact mucus exclusion, and low contact time.
• 4-SURE-style sulfur targeting became more interesting. Newer functional profiling found an 8-week sulfide-reducing diet in mild-to-moderately active UC increased alpha diversity, reduced H₂S-producing taxa, changed sulfur-metabolizing genes, and decreased H₂S production plus indole.
• IAP may bridge ALP, sulfate-reducing bacteria, LPS, and tight junctions. This is mechanistic/research-grade; serum ALP still needs source-fraction workup and should not be equated with intestinal IAP activity.
• Lipids are more likely biomarker/readout than primary cause. A bidirectional Mendelian-randomization study found null causal effects of major lipid indices on IBD/CD/UC risk, so Paul’s flare-related cholesterol changes remain a personalized downstream gut-liver/inflammatory clue rather than proof that cholesterol drives UC.
• Food triggers remain personal threshold probes. Scite supports careful individualized dairy/wheat/gluten tracking, but not universal claims that dairy or gluten are root causes of UC. The milk/oral-tolerance pass adds that classic IgE allergy, non-IgE milk-protein hypersensitivity, eosinophilic/mast-cell overlap, lactose intolerance, and non-allergy dairy-triggered UC amplification should be kept separate.

Functional distal microenvironment update — 2026-06-29

The scite-heavy functional microenvironment pass strengthens the model that Paul’s target is not a generic “better microbiome,” but a rectal/distal functional state: lower H₂S/indole/protein-fermentation pressure, adequate SCFA/butyrate ecology, intact mucus exclusion, and lower stool contact time.

Key refinements:

• 4-SURE functional profiling (DOI: 10.1093/ibd/izaf177) directly measured the intended targets: alpha diversity rose, H₂S-producing taxa fell, sulfur-metabolizing genes changed, and H₂S plus indole decreased.
• The 4-SURE feasibility study (DOI: 10.1093/jn/nxac093) showed promising but uncontrolled signals: 46% clinical response, 36% endoscopic improvement, fecal SCFAs +69%, but 7% worsened.
• Diet/H₂S evidence argues against simplistic rules: protein can raise H₂S, but fiber and diet matrix can reduce H₂S even when protein is not low.
• F. prausnitzii/Roseburia remain the beneficial counterweight to pathobiont/toxin pressure, but stool measurements must be interpreted with pH, bile, substrate, strain/phylogroup, and mucosal-vs-fecal limitations.
• UCAC/contact-time remains a gating variable: a fermentable substrate is only helpful for Paul if it improves barrier/metabolite ecology without worsening retention, gas, straining, incomplete evacuation, or rectal contact time.

This update keeps H₂S as dose/context dependent rather than universally harmful; contradiction papers found fecal H₂S and measured sulfide detoxication defects do not fully explain UC.

Central causal graph

Food triggers / stress / sleep loss / infection / dysbiosis
        ↓
Distal mucosal stress + mucus/barrier disruption
        ↓
Microbial metabolites + irritants contact vulnerable rectal tissue
        ↓
Mucus response + constipation/retention/incomplete evacuation
        ↓
More contact time + more local inflammation
        ↓
Blood, rectal pain, calprotectin rise, possible cecal/ileocecal symptoms
        ↓
Systemic inflammatory/liver-lipid response: cholesterol and ALP shifts
        │
        └──► PERSISTENCE LOOP: inflammation → mucosal hypoxia + goblet-cell/mucus-PC
             depletion + motility change → *more* barrier failure and contact time,
             which re-enters the graph near the top even if the original trigger is gone.

The persistence loop is the reason “remove the trigger” is not the same as “cure”: durable remission requires interrupting the self-reinforcing cycle (hypoxia, mucus depletion, retention), not only removing the initial insult. This reframes every intervention as a second question — does it break the feedback loop, or only remove one upstream cause? See the model-refinement note dated 2026-07-04 below.

Why proctitis/distal first? Hypotheses to score

Hypothesis	Why it fits	What would support it	Status
Stool contact-time / constipation	Paul’s sequence includes constipation and distal symptoms	symptom improvement with stool-softening/motility changes; rectal-local irritation literature	active
Rectal mucus/barrier weakness	Mucus appears before blood	evidence for mucus/phosphatidylcholine/goblet cell defects in UC	active
Distal microbial metabolite gradient	Rectum exposed to final fecal metabolite mix	studies on H2S, nitric oxide, bile acids, distal dysbiosis	active
Local immune/microvascular features	UC classically starts in rectum	anatomy/immunology literature	pending
Pelvic floor/autonomic stress	stress worsens; rectal pain/constipation	pelvic floor/tenesmus/autonomic evidence	pending
Specific triggers hitting distal mucosa	dairy rapidly causes blood	elimination/rechallenge data, allergy/immune/mast-cell evidence	active

Current answer: why microbial positioning / pathobionts matter?

Working answer after Digest 009: the core microbial question is less “which organisms are in the stool?” and more where microbes and microbial toxins sit relative to the inner mucus layer and epithelium.

• Healthy MUC2 inner mucus normally excludes bacteria while the outer mucus/lumen hosts commensals.
• Active UC mucus can become penetrable, allowing bacteria or bacteria-sized particles to approach the epithelium.
• Emerging 2025 Aeromonas/aerolysin evidence suggests a possible UC subgroup where a bacterial toxin depletes protective intestinal macrophages before overt inflammation.
• Fusobacterium, sulfate-reducing bacteria/H2S, Akkermansia, and Ruminococcus gnavus all illustrate the same lesson: strain, location, barrier state, and virulence/metabolism matter more than simple genus-level labels.
• Stool tests may be useful clues, but they may miss the decisive mucosa-associated or tissue-adjacent process.

Current answer: why beneficial commensals / butyrate ecology matter?

Working answer after Digest 010: the microbial ecology branch has a beneficial side as well as a pathobiont side. The key question is not only whether harmful microbes or toxins reach the epithelium, but whether beneficial butyrate-producing ecology is strong enough to maintain epithelial energy, anti-inflammatory signaling, and mucus/barrier reserve.

• Faecalibacterium prausnitzii is reduced in IBD overall and meaningfully reduced in UC subgroup analyses, though Crohn’s signals are often stronger.
• Roseburia hominis plus F. prausnitzii reduction is a UC-specific butyrate-producer dysbiosis pattern.
• E. coli Nissle 1917 has unusually strong strain-specific UC maintenance evidence, including equivalence trials versus mesalazine.
• De Simone/original VSL#3/Visbiome-style multi-strain probiotics have active-UC signals, but product identity and evidence certainty matter.
• Psyllium/Plantago may bridge constipation management and butyrate ecology, but fiber tolerance is central because generic fiber can worsen UC-associated constipation symptoms in some patients.
• Direct butyrate delivery remains mixed; supporting endogenous ecology and epithelial redox capacity may be more important than simply adding butyrate.

Current answer: how should constipation-safe fiber / food / full-evacuation methods be framed?

Working answer after Digest 011: the constipation/butyrate branch should not be simplified to “more fiber.” A good intervention candidate should reduce contact time + straining + incomplete evacuation without increasing mucus/blood.

• UCAC reviews warn generic fiber advice can worsen symptoms in some UC patients.
• Psyllium has strong chronic-constipation fiber evidence and a small UC remission-maintenance signal, but flatulence/tolerance matter.
• Kiwi is a promising whole-food constipation candidate because kiwi/prunes/psyllium all improved chronic constipation, with kiwi having the lowest adverse-event/dissatisfaction signal in one trial.
• PHGG is a potentially gentler soluble prebiotic but has weaker constipation evidence and is not UC-specific.
• Resistant starch and 4-SURE-style fermentation/sulfur strategies are mechanistically promising but need careful UCAC/contact-time monitoring.
• PEG and other guideline-backed non-fermentative constipation options may be safer clinician-discussion paths when fiber worsens retention.
• Footstool/supported-squat posture and pelvic-floor evaluation belong in the low-systemic-exposure branch because they target evacuation mechanics directly.

Current answer: why constipation/contact time/pelvic floor matter?

Working answer after Digest 008: Paul’s mucus → constipation/incomplete evacuation → blood sequence maps onto recognized ulcerative-colitis-associated constipation (UCAC) and distal proctitis mechanics.

• In one UC cohort, 46% met a working proximal-constipation definition; active disease and left-sided disease were associated with higher odds.
• UCAC can mimic refractory inflammation and may lead to inappropriate escalation if fecal stasis/contact-time issues are missed.
• Fecal stasis/contact time may prolong exposure of a weak rectal barrier to microbes, sulfide, bile acids, friction, and inflammatory exudate.
• Tenesmus, pelvic-floor guarding, dyssynergia, and rectal pain can form a feedback loop with inflammation.
• Local rectal therapies have strong evidence/guideline support for proctitis, reinforcing that rectal-local disease needs rectal-local thinking.

Current answer: why mucus phosphatidylcholine matters?

Working answer after Digest 006: mucus PC is still one of the strongest barrier-repair hypotheses, but the intervention story is formulation-specific and contested.

• UC rectal mucus PC has been reported to be about 70% lower than Crohn’s/controls, independent of disease activity.
• Early delayed/retarded-release PC RCTs and a 2021 meta-analysis showed strong clinical/endoscopic/histologic signals.
• Larger 2024 LT-02 induction trials failed the primary endpoint and were stopped for futility, so the clinical evidence is mixed rather than simply positive.
• Generic oral lecithin/systemic PC should not be assumed equivalent to colon-targeted delayed-release PC.
• PC species and metabolism may matter: PC34:1, PEMT, and PCYT1α connect this branch to lipid metabolism and Paul’s genetic/lipid interests.

Current answer: why redox / butyrate oxidation matters?

Working answer after Digest 007: redox/butyrate oxidation is a root-cause-grade mechanistic branch, but Pravda-style cure protocols remain safety-sensitive and clinically unproven at RCT level.

• Santhanam 2007 found about 80% lower mitochondrial acetoacetyl-CoA thiolase activity in UC biopsies, with other butyrate oxidation enzymes normal.
• The defect was restored ex vivo by a reducing agent and UC biopsies produced more hydrogen peroxide, supporting a reversible redox-linked bottleneck.
• Roediger’s “starved gut” frame and Pravda’s hydrogen-peroxide/radical-induction frame overlap: impaired energy metabolism may produce oxidative signals that damage barrier and recruit neutrophils.
• Hydrogen sulfide is plausible as an inhibitor of butyrate oxidation, but modern reviews caution that H2S has dose/context-dependent effects, not simply “sulfur bad.”
• Hydrogen peroxide enemas and chlorine dioxide/CDS/MMS are explicit danger zones; RDLA/STS claims belong on clinician-discussion lists, not DIY protocol lists.

Current answer: why rectum/proctitis first?

Working answer after Digest 002: UC may start distally because the rectum is a low-reserve, high-contact barrier threshold zone.

• UC is clinically described as starting in the rectum and extending proximally.
• Healthy colon has an inner MUC2-rich mucus layer that keeps bacteria away from epithelium; active UC mucus can become penetrable.
• Mucus phosphatidylcholine may thin toward the rectum, potentially leaving the lowest protective reserve there.
• The rectum is a relative stasis/contact site, so constipation/incomplete evacuation may amplify exposure to stool microbes/metabolites.
• Colonocytes need beneficial luminal fuels such as SCFAs/butyrate, but weak barrier + impaired redox/butyrate oxidation can turn the same lumen into a damaging contact environment.

This gives a practical causal frame: rectal-first disease may be a barrier-threshold failure at the place with the least reserve and most contact time.

Current answer: why dairy/gluten/wheat matter?

Working answer after Digest 003: dairy/gluten/wheat should be modeled as personal trigger/amplifier nodes, not proven universal root causes.

• Population-level evidence does not clearly show dairy worsens IBD course for everyone, but many IBD patients report dairy-flare connections and Paul has a strong personal dairy → blood signal.
• Dairy could act through milk protein/casein immune reactivity, lactose/FODMAP fermentation, fat/bile/microbiome effects, histamine/mast-cell responses, or low-barrier timing.
• Older cow-milk antibody studies argue against simple universal circulating milk-protein allergy in UC; one small later case-control study suggests possible cow milk/casein allergy signal in UC.
• Gluten/wheat restriction improves self-reported symptoms in many IBD patients, but objective inflammatory benefit is weak/negative so far; wheat/fructans/ATIs may matter more than gluten itself for some people.
• For Paul, the question is component specificity and timing: which dairy/wheat component crosses the rectal barrier threshold, at what dose, and in what flare/sleep/stress/constipation state?

Current answer: why sleep/apnea/circadian disruption matters?

Working answer after Digest 004: sleep is a barrier-reserve and inflammatory-threshold controller, not merely a lifestyle footnote.

• Chronic poor sleep in a 2025 prospective UC study was associated with higher UC relapse rate: 34.5% vs 10.3%.
• Inactive IBD patients still show poorer sleep than controls, suggesting sleep disruption may reflect subclinical inflammation or contribute to it.
• Circadian rest-activity disruption has been linked to permeability, calprotectin, TNF-α, dysbiosis, and fewer SCFA/butyrate-associated taxa.
• OSA appears more prevalent in IBD/UC cohorts and may add intermittent hypoxia, sympathetic activation, and inflammatory burden.
• For Paul, sleep/apnea may explain why dairy/gluten/stress/stool-contact triggers cross the bleeding threshold some weeks and not others.

Current answer: why ALP/cholesterol matter?

Working answer after Digest 005: ALP/cholesterol are objective biomarker clues, but they are not yet interpretable as a single mechanism.

• Elevated serum ALP can come from liver/bile ducts, bone, intestine, or mixed sources; ALP isoenzymes plus GGT/bilirubin/AST/ALT context are essential.
• PSC belongs on the clinician-question list in UC with persistent cholestatic enzymes, but should not be assumed from ALP alone.
• Intestinal alkaline phosphatase biology is highly relevant to barrier/LPS/endotoxin control, even though blood ALP is not the same thing as fecal/intestinal ALP activity.
• Population-level IBD lipid meta-analysis often shows lower TC/LDL/HDL with active disease; Paul’s reported cholesterol rise during flares is therefore a personal-outlier clue needing careful tracking.
• Bile acid–microbiome signaling connects liver, cholesterol metabolism, barrier function, immune response, and dysbiosis.

Paul’s key observations to explain

• Dairy → blood shortly after.
• Some gluten sensitivity.
• Stress worsens symptoms.
• Lack of sleep worsens symptoms; sleep apnea may be relevant.
• Early mucus while stool remains well formed.
• Temporary constipation worsening before blood.
• Rectal pain and sometimes cecal pain.
• Cholesterol rises during flares and falls when controlled.
• ALP rises with symptoms/calprotectin and falls as symptoms improve; ALP tends to run high.

Research digestion rules for this page

For every source we digest, ask:

1. Does it support, weaken, or modify the central theory?
2. Which causal node does it address: barrier, mucus, microbiome, metabolite, stool retention, diet trigger, stress/sleep, immune response, liver/lipid/ALP?
3. Does it explain distal/proctitis onset?
4. Does it explain Paul’s mucus → constipation → blood sequence?
5. Does it suggest a testable intervention or biomarker?
6. Does it create a clinician question?

Current highest-priority literature questions

• What causes UC to begin in the rectum?
• What evidence links mucus-layer/phosphatidylcholine defects to UC?
• What evidence links hydrogen sulfide/nitric oxide/redox stress to UC?
• What evidence links constipation/stool contact time to proctitis activity?
• What evidence links dairy/wheat sensitivity to rectal bleeding in UC?
• What evidence links sleep apnea/sleep deprivation to IBD activity?
• What evidence links gut permeability/endotoxin to cholesterol changes?
• What explains elevated ALP tracking with IBD activity/calprotectin?

Digest index

The per-digest evidence recaps that used to live inline here now live in their canonical places to avoid duplication: each journal find holds the raw pass, and each mechanism page holds the durable synthesis. This table is the map; the branches are summarized in the “Current answer” sections above.

Date	Digest (journal find)	Canonical mechanism page
2026-06-17	[[2026-06-17-uc-causal-mechanism-digest-001	Digest 001 — causal mechanisms]]
2026-06-17	[[2026-06-17-uc-distal-proctitis-onset-digest-002	Digest 002 — distal/proctitis onset]]
2026-06-17	[[2026-06-17-uc-dairy-gluten-food-trigger-digest-003	Digest 003 — dairy/gluten/wheat]]
2026-06-17	[[2026-06-17-uc-sleep-apnea-circadian-digest-004	Digest 004 — sleep/apnea/circadian]]
2026-06-18	[[2026-06-18-uc-alp-cholesterol-gut-liver-digest-005	Digest 005 — ALP/cholesterol]]
2026-06-18	[[2026-06-18-uc-mucus-phosphatidylcholine-digest-006	Digest 006 — mucus PC]]
2026-06-18	[[2026-06-18-uc-redox-butyrate-pravda-digest-007	Digest 007 — redox/butyrate/Pravda]]
2026-06-18	[[2026-06-18-uc-constipation-contact-time-digest-008	Digest 008 — constipation/contact time]]
2026-06-18	[[2026-06-18-uc-pathobiont-mucus-layer-digest-009	Digest 009 — pathobionts/mucus ecology]]
2026-06-18	[[2026-06-18-uc-beneficial-commensals-probiotics-prebiotics-digest-010	Digest 010 — beneficial commensals]]
2026-06-19	[[2026-06-19-uc-constipation-safe-fiber-evacuation-digest-011	Digest 011 — safe fiber/evacuation]]
2026-06-27	[[2026-06-27-uc-scite-validation-central-theory	Scite validation pass]]
2026-06-28	[[2026-06-28-uc-milk-allergy-oral-tolerance-digest	Milk allergy / oral tolerance]]
2026-06-29	[[2026-06-29-uc-functional-distal-microenvironment-scite-pass	Functional distal microenvironment]]

Model refinements & open modeling questions (2026-07-04)

These are structural refinements to the model itself (evidence_level: speculative). They do not add new sources; they sharpen how the existing branches fit together and what to test next.

R1. Name the unifying idea: the rectal barrier-reserve threshold

Nearly every branch (food triggers, sleep, stress, contact time, pathobionts) behaves as an amplifier that pushes a low-reserve rectal barrier over a bleeding threshold, rather than as an independent cause. Stating this explicitly yields a testable prediction: symptoms should track the sum of concurrent stressors, not any single one. That is exactly why the same dairy exposure bleeds some weeks and not others. Practical consequence: the personal log should capture a daily composite load (dairy + poor sleep + constipation days + stress), not just single exposures. See key-open-questions.

R2. Redox/butyrate vs contact-time is a real internal tension → argues for delivery route

The redox branch says the colonocyte is fuel-starved and wants more butyrate ecology; the contact-time branch says fermentable substrate is dangerous if it worsens retention/gas/H₂S. The same molecule (fermentable fiber) sits on both sides. The resolution the model predicts: delivery route matters more than the molecule — this is the mechanistic argument for rectal butyrate/SCFA or targeted distal delivery over oral fermentable fiber in distal disease. Cross-links: redox-butyrate-thiolase-uc, constipation-safe-fiber-full-evacuation-uc.

R3. ALP/cholesterol: score an explicit confound against the gut-liver readout hypothesis

The model treats flare-rising cholesterol as a gut-liver inflammatory readout. A simpler competing hypothesis deserves explicit scoring: flares change diet and behavior (more red meat/dairy, less exercise, more cortisol), all of which raise LDL independently of gut inflammation. Discriminator: an inflammatory-readout mechanism should move cholesterol with calprotectin on a similar lag; a diet/behavior confound should track the food log instead. This is resolvable once the personal lipid/flare timeline is built. See alp-cholesterol-gut-liver-lipid-axis-uc.

R4. Close the loop: model persistence, not just onset

The graph above now includes the persistence loop (inflammation → hypoxia + mucus/PC depletion + motility change → more barrier failure). The model was previously strong on onset and weak on why UC persists. Consequence for the cure question: rank candidate interventions by whether they interrupt the feedback cycle, not only whether they remove an upstream trigger.

R5. Under-explored node: bile acids

Paul’s model has dairy (→ fat → bile load), a distal/rectal focus, cholesterol changes, and a microbiome branch (microbes transform bile acids) — bile-acid metabolism sits at the intersection of all four, and altered bile-acid pools are a recognized driver of distal colonic secretion/irritation. Currently only a passing mention in Digest 005. Candidate for its own branch/mechanism page and a dedicated literature pass. Filed in key-open-questions.

R6. Two evidence-backed levers currently under-weighted

• FMT is the most direct test of the microbial-ecology hypothesis and has three positive induction RCTs — see new page microbiome transfer. (Note: Paramsothy 2017 found Fusobacterium associated with FMT non-remission, tying FMT outcomes back to the pathobiont branch.)
• Nicotine has real induction-RCT evidence for active UC (not just anecdote), though not for maintenance — see new page smoking paradox.

Version history

• 2026-06-17 v0.1 — Initial scaffold from Paul’s observations and Notion source queue. Awaiting systematic source digestion.
• 2026-06-17 v0.2 — Promoted source digest 001: mucus PC/barrier, colonocyte redox/thiolase, microbial niche, and gut-liver-lipid axis moved into core theory.
• 2026-06-17 v0.3 — Promoted source digest 002: rectal-first disease modeled as a low-reserve/high-contact distal barrier-threshold failure; added mucus penetrability, PC gradient, fecal stasis/contact-time, and SCFA/fecal-stream paradox.
• 2026-06-17 v0.4 — Promoted source digest 003: dairy/gluten/wheat modeled as personal trigger/amplifier nodes that may cross Paul’s rectal barrier threshold; added distinction between universal dietary rules and individualized objective trigger tracking.
• 2026-06-17 v0.5 — Promoted source digest 004: sleep/apnea/circadian disruption modeled as a barrier-reserve and inflammatory-threshold controller; added relapse, OSA, permeability, calprotectin, TNF-α, dysbiosis, and melatonin evidence.
• 2026-06-18 v0.6 — Promoted source digest 005: ALP/cholesterol/gut-liver-lipid axis modeled as an objective biomarker branch; added ALP source-fraction logic, PSC clinician-screening questions, IAP/LPS/barrier biology, bile acid–microbiome signaling, and the contradiction between Paul’s cholesterol-flare pattern and population lipid meta-analysis.
• 2026-06-18 v0.7 — Promoted source digest 006: mucus phosphatidylcholine modeled as a core barrier-repair branch, while intervention evidence was reframed as formulation-specific and mixed after negative/mixed LT-02 multicenter results.
• 2026-06-18 v0.8 — Promoted source digest 007: redox/butyrate/thiolase branch elevated as root-cause-grade mechanism; Pravda/Roediger overlap clarified; H2S nuance and high-risk redox safety flags added.
• 2026-06-18 v0.9 — Promoted source digest 008: constipation/contact-time/pelvic-floor mechanics elevated as a core personal-pattern branch; UCAC prevalence/active-distal association, pelvic-floor treatment signal, and local rectal therapy evidence added.
• 2026-06-18 v1.0 — Promoted source digest 009: pathobiont/mucus-layer ecology elevated as a core branch; added microbial positioning logic, Aeromonas/aerolysin emerging subgroup signal, Fusobacterium oral-gut caution, SRB/H2S link, and Akkermansia/R. gnavus context-dependence.
• 2026-06-19 v1.2 (see above).
• 2026-06-29 v1.3 — Functional distal microenvironment pass integrated.
• 2026-07-04 v1.4 — Structural pass: condensed the inline per-digest recaps into a Digest index (detail now lives in the linked journal finds and mechanism pages); added the persistence loop to the causal graph; added model refinements R1–R6 (barrier-reserve threshold, redox-vs-contact-time delivery-route argument, ALP/cholesterol confound, persistence framing, bile-acid node, and the FMT + nicotine levers).