Vitamin B1 (Thiamine)

Clinical Summary

Thiamine is an essential water-soluble vitamin whose active form (thiamine pyrophosphate, TPP) serves as a coenzyme for pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, transketolase, and branched-chain α-KGDH. Humans cannot synthesize it; body stores last ~2–3 weeks.

The compound's biology bifurcates cleanly into two eras:

1. Deficiency correction — the gold-standard story. Beriberi, Wernicke-Korsakoff, infantile beriberi, refeeding syndrome. Dramatic response, bulletproof evidence, 5/5.
2. Pharmacological super-dosing in non-deficient individuals — a much weaker story than supplement marketing implies. The 2026 BOND trial (PMID: 41571333) found benfotiamine 600 mg/day × 12 months NULL on 13 objective neurophysiological endpoints in diabetic neuropathy, significantly downgrading the most-touted non-deficiency use case. Sepsis mortality benefit exists only in deficient subgroups.

Who benefits most:

• People with documented deficiency (whole-blood <50 nmol/L or transketolase activation >1.25)
• Chronic loop diuretic users (30–98% have deficiency)
• Alcohol use disorder (primary Wernicke prevention)
• Post-bariatric surgery (18–49% post-RYGB)
• Hyperemesis gravidarum (Wernicke risk)
• Chronic metformin users (20–30% marginal deficiency)
• Quiescent IBD with chronic fatigue (Bager protocol)
• Mendelian thiamine-responsive conditions (TRMA / Rogers syndrome, BTBGD)

Who does NOT benefit (but the supplement industry says they do): healthy adults seeking "energy boost", people with vague dysautonomia/fatigue without documented deficiency, Parkinson's patients expecting Costantini-style reversal, long-COVID patients expecting TTFD cure.

Indications & Evidence

Reading this table: Stars = evidence volume. Type = what kind of evidence (see legend). BH = Bradford Hill causal strength (/9). Safety = FAERS/trial signals for THIS specific indication. The biggest 2026 change: benfotiamine for DSPN dropped from 4/5 to 3/5 after the BOND trial (PMID: 41571333) showed null objective endpoints at 12 months despite confirmed thiamine analyte elevation — a clean surrogate-endpoint-trap demonstration.

Type codes: DC=Direct causation | PC=Probable | UCC=Unreplicated causal | BC=Biomarker correlation | SE=Surrogate endpoint | ME=Mechanistic extrapolation | AHE=Animal→human | OA=Observational | RC=Reverse causation | CF=Confounded | FA=Folk/anecdotal | NE=No evidence BH: 7–9=strong causal | 5–6=moderate | 3–4=weak | 1–2=speculative | 0=none Safety flags: -- No signals | MON Monitor | WARN safety signal | AVOID Contraindicated Stars: 5/5 Multiple large RCTs + MA | 4/5 Several human RCTs | 3/5 Human pilot data | 2/5 Animal/limited human | 1/5 No evidence/debunked/folk

Prescribing

Dosing Table

Formulation Table

Condition-Specific Protocols

Wernicke-Korsakoff Syndrome (Medical Emergency)

Evidence: 5/5 | PMID: 22540422, 23818100 (Cochrane)

Phase 1: Acute treatment

• Thiamine 500 mg IV infused over 30 min, TID × 3–5 days
• Give thiamine BEFORE any glucose — glucose infusion on empty thiamine stores precipitates Wernicke's
• Co-administer Mg sulfate 2–4 g IV (TPK requires Mg cofactor)
• Clinical endpoint: ophthalmoplegia resolves in hours, ataxia in days-weeks, confusion variable

Phase 2: Transition (days 4–10)

• Thiamine 250 mg IV/IM daily × 3–5 days

Phase 3: Maintenance

• Thiamine 100 mg PO daily lifelong + B-complex + abstinence if alcohol-related

Drug interaction timing: Mg must be repleted or TPP formation fails. Correct hypomagnesemia (common in AUD). Expected outcomes: Eye movements correct within hours; permanent Korsakoff develops if treated late. Stop/reassess criteria: Never stop maintenance in chronic AUD.

Heart Failure on Chronic Loop Diuretics

Evidence: 4/5 | PMID: 1867241, 7573094, 35842069

Phase 1: Initiation

• Thiamine HCl 100 mg BID × 4 weeks
• Baseline: check whole-blood thiamine or transketolase activation if available

Phase 2: Therapeutic (continuous)

• 100–200 mg/d oral; split BID if >100 mg
• Recheck LVEF at 3 months (expect 2–5% absolute improvement in deficient patients)

Phase 3: Maintenance

• Continue as long as diuretic therapy continues
• Annual thiamine status check

Expected outcomes: Symptomatic benefit (exercise tolerance, dyspnea) may exceed LVEF changes. Mortality benefit not consistently demonstrated (Xu 2022 meta). Flagship trial NCT05873881 COLT-HF (N=2500, Phase 3) currently recruiting. Stop/reassess criteria: If diuretic discontinued, reduce to maintenance 10–25 mg/d.

Quiescent IBD with Chronic Fatigue (Bager Protocol)

Evidence: 4/5 | PMID: 33210299, 34592862

Phase 1: Trial period (4 weeks)

• Thiamine HCl 200 mg TID with meals = 600 mg/d
• Baseline IBDFS score

Phase 2: Response assessment (week 4)

• If IBDFS improved by ≥2.6 points (Bager trial mean effect): continue
• If no improvement: discontinue — responders usually evident by week 4

Phase 3: Maintenance

• 600 mg/d × 6 months (extension study data)
• Split dosing reduces GI upset

Drug interaction timing: Space from sulfasalazine by 2 h. Expected outcomes: Clinically meaningful fatigue reduction; mechanism unclear (possibly subclinical deficiency correction). Stop/reassess criteria: No response at 4 weeks, or flare onset.

Post-Bariatric Surgery Prophylaxis (ASMBS 2025)

Evidence: 5/5 | PMID: 40345894

Phase 1: Immediate post-op (0–6 months)

• Thiamine 50–100 mg/d oral
• Baseline level at 3 mo
• If persistent vomiting: 100 mg IM weekly to prevent Wernicke

Phase 2: Stable (6–12 months)

• 50–100 mg/d oral
• Thiamine level check at 6 and 12 months

Phase 3: Lifelong

• 50–100 mg/d oral indefinitely
• Annual level check
• Re-escalate at any vomiting episode, pregnancy, intercurrent illness

Drug interaction timing: n/a for thiamine. Expected outcomes: Wernicke prevention (18–49% deficiency rate post-RYGB). Clinical vigilance even on prophylaxis — case reports of Wernicke persist on supplementation when vomiting occurs. Stop/reassess criteria: Never stop after bariatric surgery.

Safety

Interactions Table

Contraindications

• Absolute: None for oral thiamine. History of severe IV anaphylaxis → oral route instead (PMID 41598206: oral typically safe even in parenteral-allergic patients)
• Relative (IV): Multiple drug allergies — slow push, epinephrine available, consider desensitization (PMID 41598206)
• Sulbutiamine: Bipolar disorder (mania case reports PMID 16861144); SSRI caution (community reports); dependence liability
• TTFD: Distinct sulfur body odor (confirmed side effect); MTHFR/CBS variants may amplify anxiety/activation

Adverse Effects

Common (>1%, oral):

• GI upset at >100 mg single dose (5–10%): nausea, bloating, diarrhea — split dose fixes
• Bright yellow-green urine: universal >50 mg/day, harmless excretion indicator

Uncommon (0.1–1%): Headache, dizziness (usually IV), flushing

Rare (<0.1%):

• IV anaphylaxis: historically estimated 1 in 100,000 doses; modern IV-push series (PMID 31932197, 35491726) suggest much lower with current protocols
• IM injection site reactions
• Japanese case (PMID 37460290): formulation/excipient-driven anaphylaxis in IV B-complex

Extremely rare: No documented oral toxicity despite doses >1000 mg/d. Water-soluble with efficient renal excretion.

FAERS Signal Table (from BioMCP / OpenFDA)

Reading FAERS: Thiamine is usually concomitant in polypharmacy reports — true drug-attributable anaphylaxis in modern IV push series is <1 per 250,000 doses (tertiary center data). The real signal from dedicated pharmacovigilance (PMID 41864862) is drug-INDUCED thiamine deficiency from 38 drugs — furosemide, metformin, fedratinib, metronidazole, fluorouracil top the list. For benfotiamine (976 reports): no distinct signal — background co-med noise.

Monitoring Table

Special Populations

Renal Impairment

Hepatic Impairment

Pregnancy / Lactation

• FDA Category A
• RDA 1.4 mg/d (up from 1.1)
• Hyperemesis >3 wk: 100 mg IV with rehydration (ACOG Bulletin 189)
• Lactating women in at-risk populations: 10 mg/d oral (PMID 39699595, RCT-supported for infant language development)
• Infantile beriberi if mother deficient — still reported globally

Pediatric

• No upper limit established
• HF on diuretics: 25–50 mg/d insufficient (PMID 41872295) — higher doses likely needed
• WE presentations 61% full remission with prompt treatment (PMID 39997622)

Synergies & Stacking

Antagonists: Alcohol, raw-fish thiaminase, betel nut, sulfites, tannins. See Interactions Table.

Individual Response Modifiers

Sex-Specific Considerations

Genetic Modifiers

Ethnic differences persist after dietary adjustment (PMID 41519268, UK NDNS N=5,657): black participants 5% deficiency vs white 0.5% vs Asian 1.3%; higher ETKAC despite comparable intake. Likely reflects transporter/metabolic variation — rationale for broader screening in black populations at risk.

Community & Anecdotal Evidence

Disclaimer: This section captures real-world user reports from online communities. None of this constitutes clinical evidence. N-sizes are approximate. Selection bias, placebo effect, recall bias, and survivor bias are inherent. Presented for completeness, not medical guidance.

Dominant Sentiment

Polarized across forms. Mainstream thiamine HCl has low folk traction (boring vitamin); lipid-soluble analogs (TTFD, sulbutiamine) and the Costantini HDT Parkinson's protocol have massive traction that substantially exceeds clinical evidence.

What Users Report

Community Dosing vs Clinical

Popular Stacks (Community)

Red Flags & Skepticism Notes

• Single-source dependency: The entire Western TTFD-for-dysautonomia movement traces to ≤5 people — Lonsdale/Marrs (Hormones Matter), Overton (EONutrition), Costantini/Bryan (Parkinson's HDT). Single-source hype is a red flag.
• Direct financial COI: Elliot Overton founded Objective Nutrients, which sells the dominant TTFD product (Thiamax). His clinical claims are directly tied to his product sales. Not MLM technically, but concentrated-product ecosystem.
• Unfalsifiability pattern: Three dedicated Hormones Matter articles explain "paradoxical reactions" via glutathione, methylation, or patience — making any adverse response to TTFD "proof the protocol is working." This is unfalsifiable and conveniently prevents discontinuation.
• Root-cause universalism: Hormones Matter positions B1 deficiency as underlying POTS + SIBO + long COVID + PD + fatigue + anxiety + depression + dysautonomia. When one nutrient is proposed as the cause of everything, signal-to-noise is poor.
• Costantini reproducibility: Michael J. Fox Foundation explicitly declines to recommend HDT. Cambridge/Dutch neurologists publicly attribute results to placebo or misdiagnosis. Closed Facebook groups moderate out negative testimony — survivor bias is severe.
• Sulbutiamine dependence: Longecity has dedicated threads with users reporting addiction; withdrawal symptoms lasting 1–2 weeks. Under-disclosed in nootropic marketing. Two published mania case reports in bipolar patients.
• Supplement industry "high-potency" B-complex marketing: "B-100" = 100 mg thiamine, 100× the RDA, mostly excreted. Works because "yellow urine feels like it's doing something."

Folk vs Clinical Reality Check

Where community experience aligns with clinical data:

• Benfotiamine for diabetic neuropathy short-term symptoms (aligned on both traction and modest-positive short-term effect)
• Magnesium co-supplementation (universal community wisdom matches TPK biology)
• Wernicke prophylaxis in AUD (community + medical consensus)

Where community experience diverges dangerously from clinical data:

• Costantini HDT Parkinson's — 70% response claim vs failed community replication + no placebo-controlled trial
• TTFD for long COVID / POTS — massive community use vs zero RCT support
• Sulbutiamine as benign nootropic — community underappreciates tolerance/dependence/bipolar trigger
• Benfotiamine long-term diabetic neuropathy — community enthusiasm based on old short-term trials; BOND 2026 (PMID 41571333) null at 12 months on 13 objective endpoints

Most likely explanations for divergence: (a) placebo effect in uncontrolled protocols, (b) correction of mild undiagnosed deficiency being attributed to pharmacological super-dosing, (c) survivor bias in closed online communities, (d) unfalsifiability framing of paradoxical reactions.

Deep Dive: Mechanisms & Research

Established Coenzymatic Roles (ATARAXIA-vetted, clinical translation established)

1. Pyruvate dehydrogenase (PDH) — pyruvate → acetyl-CoA entry into Krebs cycle. Rate-limiting for aerobic carbohydrate metabolism. Deficiency → lactic acidosis. Clinical translation: absolute.
2. α-Ketoglutarate dehydrogenase (α-KGDH) — Krebs cycle step. Clinical translation: absolute.
3. Transketolase — pentose phosphate pathway → NADPH + ribose-5-P. Gold-standard deficiency marker. Clinical translation: absolute.
4. Branched-chain α-KGDH — leucine/isoleucine/valine catabolism. Clinical translation: absolute.

Emerging Mechanisms (2024–2026 — preclinical to hypothesis-level)

5. TPK1 / Astrocytic TFEB / Aβ clearance — PMID 41506439: astrocytic TPK1 deficiency worsens Aβ burden in 5xFAD mice; overexpression rescues via TFEB-driven endocytosis. Novel AD target. Preclinical only.
6. HIF-1α suppression under neurotoxic stress — PMID 41707701: thiamine preserves intracellular Fe, restores PHD activity → HIF-1α degradation, attenuates ER stress. Preclinical only.
7. PPARγ natural ligand activity — PMID 41368574: molecular docking + adipogenesis assays show thiamine binds PPARγ LBD with rosiglitazone-like potency. Hypothesis-level, computational + cellular.
8. TPP antiplatelet effect (PI3K-Akt/MAPK) — PMID 41865870: supraphysiological TPP suppresses platelet aggregation, attenuates arterial thrombosis in mice without impairing hemostasis. Preclinical + ex-vivo human platelets.
9. Gut microbiome–thiamine–MASLD axis — PMID 41560354: B. virosa-derived TMP → hepatic TPP ↑ → BCKDH activation → MASLD suppression. Mouse + human correlation.
10. Gut microbiota–thiamine–placental Notch axis — PMID 41456070: maternal gut Lactococcus → fecal thiamine ↑ → placental angiogenesis via Notch → PI3K/AKT. Rat + sow models.
11. GI motility GWAS — PMID 41558814: multi-ancestry N=268,606 converges on B1 metabolism loci (transporter + phosphate exporter). Thiamine intake stool frequency (p<0.0001, N=98,449). Provides genetic support for thiamine-motility axis claimed in dysautonomia communities.

CUT from prior version: redundant molecular-formula sections, speculative TTP neurotransmitter claims, over-detailed tissue distribution (moved to one sentence), decorative mechanism prose.

Clinical Trials (from BioMCP / ClinicalTrials.gov)

Registered totals (BioMCP): ~116 unique across thiamine (102) + benfotiamine (12) + sulbutiamine (1) + fursultiamine (1). ~75 completed, 9 active, ~32 unknown/terminated/withdrawn. Sepsis dominates registered volume (~30+ trials), with overwhelmingly negative or neutral results post-VICTAS.

Regulatory Status (from BioMCP)

• FDA: Injectable thiamine HCl Rx via ANDAs (multiple active — Eugia 2022, Caplin 2023, Fresenius Kabi supplement 2024). Oral thiamine is OTC dietary supplement. No FDA warnings on file.
• EMA: No centralized approval — national authorizations across member states.
• Germany (EU): Benfotiamine Rx as Milgamma (with pyridoxine) since 1993, licensed for painful nerve conditions.
• Japan: Fursultiamine (Alinamin) long-standing OTC product from Takeda.
• France: Sulbutiamine (Arcalion/Servier) discontinued 2020.
• Regulatory context: Thiamine is unrestricted globally for oral supplementation. Regulatory status varies for lipid-soluble analogs by member state. No centralized rating changes in 2024–2026.

Ataraxia Verdict (as of 2026-04-17)

Evidence Classification (Mode 5: Evidence Classifier)

Hype Check (Mode 1: Fallacy Radar)

• Appeal to authority — Marik's sepsis HAT protocol driven by single-center observational data before VICTAS/ACTS/STRESS showed no mortality benefit. Costantini's Parkinson's claims rest on his own open-label observations.
• Hasty generalization — Animal data on TPK1/TFEB, HIF-1α, PPARγ, and antiplatelet effects being cited in supplement marketing as if they were clinical data.
• Cherry-picking — TTFD community cites Lonsdale/Marrs framing + Overton's animal gut motility study; ignores absence of any RCT. Benfotiamine marketing still cites short-term BENDIP/BEDIP trials; silent on BOND 2026 null.
• Appeal to nature — "B-vitamins are natural therefore safe at any dose" — oral largely true, but IV hypersensitivity + sulbutiamine dependence + bipolar mania are real.
• Root-cause universalism (Hormones Matter) — B1 deficiency proposed as underlying POTS + SIBO + long COVID + PD + fatigue + anxiety + depression. When one nutrient explains everything, it likely explains less than claimed.
• Unfalsifiable framing — "Paradoxical reactions" in TTFD protocols converts any adverse response into evidence of deficiency, preventing discontinuation.
• Surrogate-endpoint trap — Repeated 2024–2026 papers report biomarker changes (HbA1c, lactate, CK-MB, Trop-I, IL-6, AGE, TRACP-5b); BOND 2026 demonstrates cleanly how biomarker elevation does NOT translate to clinical benefit.

Evidence Gaps

• No RCT at Costantini doses for Parkinson's (4 g oral + 2×100 mg IM)
• No RCT of TTFD for long COVID / POTS / dysautonomia
• No RCT comparing high-dose thiamine HCl to benfotiamine head-to-head for diabetic neuropathy
• Mortality benefit in sepsis still unclear post-VICTAS — 2026 meta-analyses give mixed signals
• Pediatric loop diuretic dosing needs higher arms (>50 mg/d)
• GLP-1 agonist effect on thiamine status — no monitoring framework despite emerging signal
• SLC19A2 heterozygous variants — T2D risk confirmed (PMID 40603556) but clinical screening not implemented
• Optimal parenteral regimen for Wernicke prevention (awaiting OpTIn analysis)

Bias Flags (Mode 4: First Principles)

• Publication bias — Short-term benfotiamine trials (6 wk symptom scores) overwhelmingly positive; long-term objective trials (12 mo, BOND) null and under-cited.
• Survivor bias in communities — Closed Parkinson's HDT Facebook groups moderate out failure testimony. Online recovery communities weight positive outliers.
• Who funded it — Milgamma-producing pharma (Wörwag, now Viatris) has funded multiple older benfotiamine neuropathy trials. BOND (PMID 41571333) was independently conducted and null.
• Who benefits from the theory — Supplement industry benefits from thiamine-deficiency-root-cause-of-everything framing; drug industry has ~zero stake in thiamine (off-patent, cheap) and no significant counter-narrative.

Manipulation Flags (Mode 2: Manipulation Shield)

• Industry marketing: "High-potency" B-complex (B-100) contains ~100× RDA of thiamine — mostly excreted. Benfotiamine marketing continues to cite BENDIP/BEDIP short-term symptom trials while BOND 2026 null result is under-reported. Proprietary "TTFD + magnesium + cofactors" formulations with premium pricing.
• Influencer economics: Elliot Overton → Objective Nutrients (Thiamax TTFD) direct financial stake in his clinical claims. Dr. Costantini's Parkinson's protocol continues to be promoted by his daughter post-mortem via b1parkinsons.org / book. Chandler Marrs' Hormones Matter as central narrative hub.
• Counter-narrative manipulation: Minimal — thiamine is off-patent and cheap, so pharma has no motive to fearmonger. However, academic neurology has been appropriately skeptical of Costantini and TTFD claims; MJ Fox Foundation's public declination of HDT recommendation is the cleanest counter-signal.
• Cui bono summary:
  • Pro-supplement winners: benfotiamine manufacturers (Milgamma/Wörwag), Objective Nutrients (TTFD/Thiamax), sulbutiamine sellers, IV vitamin clinic operators (Myers cocktail), HDT protocol authors/books.
  • Anti-supplement winners: effectively none — thiamine doesn't threaten any major drug market.
  • Pro-clinical-use winners: ICU/emergency medicine clinicians (standard of care legitimacy), hepatology (AUD management), bariatric surgery teams, endocrinology.
  • If you take it unnecessarily: very low financial harm ($1–3/mo for HCl), low biological harm (excess excreted), real risk only with high-dose sulbutiamine, TTFD protocols in unstable patients, or unmonitored IV.
• Red team highlight: The single most concerning pattern is the unfalsifiability of the TTFD paradoxical-reaction framing (three dedicated Hormones Matter articles explaining why adverse response = protocol working). This is the classic pseudoscience pattern of making the hypothesis unfalsifiable. Compare to legitimate clinical deficiency correction (Wernicke), which has immediate reversible endpoints and does not require "patience" to see results.

Decision Support (Mode 3: Clarity Compass)

• Health utility score: 7/10 — compound-intrinsic. Evidence is extremely strong for deficiency correction (saves lives, prevents permanent brain damage), moderate for specific conditional uses (IBD fatigue, HF with diuretics, post-bariatric prophylaxis), and weak-to-null for the aggressively-marketed general-wellness super-dosing use cases. Cross-domain breadth: high (cardiac, neurological, metabolic, hematologic, reproductive), but most domains only when deficiency is present.
• Opportunity cost: Minimal. Standard thiamine HCl costs $1–3/month, is water-soluble, has no tolerance, no withdrawal, no stimulant effects. Benfotiamine and TTFD add real cost ($30–60/month).
• Verdict: CONDITIONAL.
• Conditions warranting use:
  • Documented deficiency (whole-blood <90 nmol/L or transketolase activation >1.25)
  • Chronic loop diuretic therapy
  • Alcohol use disorder (any)
  • Post-bariatric surgery (lifelong)
  • Hyperemesis gravidarum >3 weeks
  • Chronic metformin use >1 year
  • Quiescent IBD with chronic fatigue (Bager protocol trial)
  • Documented diabetic peripheral neuropathy — try standard thiamine HCl first; benfotiamine only if HCl fails (BOND 2026 weakens the benfotiamine case)
  • Genetic: SLC19A2 TRMA, SLC19A3 BTBGD, TPK1 deficiency
  • Lactating women in at-risk dietary populations (10 mg/d)
  • Critically ill / sepsis / refeeding — empirical use acceptable
• Conditions NOT warranting pharmacological super-dosing (unless documented deficiency): general "energy support", long COVID, POTS, dysautonomia, Parkinson's outside a clinical trial, Alzheimer's outside BenfoTeam-AD, anxiety/depression in non-deficient, cognitive enhancement.

Bottom Line

Thiamine is the vitamin everyone thinks they might need and few pharmacologically benefit from. Its deficiency syndromes are among the most dramatic, rapidly-reversible neurological emergencies in medicine — withhold thiamine in Wernicke's and the patient dies or enters permanent Korsakoff. Pharmacologically super-dose a non-deficient person for "energy" or "long COVID," and you mostly make expensive yellow urine. The 2026 BOND trial's clean null result on benfotiamine for diabetic neuropathy is the most important 2024–2026 finding; it should significantly downgrade the supplement industry's most-touted non-deficiency use case. The TTFD-for-dysautonomia community, the Costantini Parkinson's protocol, and sulbutiamine as a "benign nootropic" are all selling more confidence than the evidence supports.

Practical summary:

• Supplement if you have a documented reason (deficiency, drug-induced, condition-specific protocol).
• Use plain thiamine HCl first — it's the cheapest, best-studied, and handles 90% of indications.
• Reserve IV for emergencies and genetic lock-and-key conditions.
• Don't believe single-investigator miracle claims without RCT replication.
• Magnesium alongside thiamine is legit, not just folk wisdom — it's the TPK cofactor.

Practical Notes

Brands & Product Selection

Standard thiamine HCl / mononitrate: Nature Made (USP verified), NOW Foods (third-party tested), Thorne Research (pharmaceutical grade), Pure Encapsulations, Kirkland (Costco — USP verified, best value).

Benfotiamine: Doctor's Best (BenfoPure formulation), Life Extension, Klaire Labs, Cardiovascular Research. Milgamma (Germany, Rx) combines benfotiamine + pyridoxine.

TTFD / Allithiamine: Ecological Formulas (Allithiamine), Cardiovascular Research, Objective Nutrients (Thiamax — note Overton COI). Alinamin (Takeda, Japan Rx).

Sulbutiamine: Niche market — quality highly variable; only purchase from vendors with CoA. Prior pharmaceutical brand Arcalion (Servier) discontinued 2020.

Quality markers: USP Verified, NSF certified, ConsumerLab approved. CoA with heavy metals <USP limits, >99% purity.

Red flags: Proprietary blends, unrealistic claims ("cures Alzheimer's"), no lot numbers, "clinical strength" with no dose, concentrated-product ecosystems with single-founder advocacy.

Storage & Handling

• Temperature: 15–25°C
• Light: Store in original container, UV-protected
• Humidity: Keep dry
• Shelf life: 2–3 years unopened; 18–24 months after opening
• Heat-stable during cooking but degraded by alkaline pH and sulfites
• TTFD: note characteristic garlic/sulfur smell — normal, not degradation

Palatability & Compliance

Standard thiamine has slight bitter/sulfurous taste. Mix with acidic juice (orange) or use capsules. TTFD users develop persistent garlic/sulfur body odor (a compliance-limiting side effect). Split-dose regimens (TID) have lower real-world compliance than BID.

The #1 determinant of thiamine efficacy is consistency. Body stores deplete in 2–3 weeks.

Exercise & Circadian Timing

No strong circadian preference. No pre/post-exercise timing need. Can cause mild GI upset at high doses — take with food. Some report mild energy boost in AM (subjective, not pharmacologically stimulant).

Reference Ranges (Expected Biomarker Changes)

Cost

Cost-effectiveness: Standard thiamine HCl is the undisputed leader. Benfotiamine's 30–40× cost premium was historically justified by short-term symptom trials; BOND 2026 weakens that rationale substantially. Sulbutiamine/TTFD premium pricing has essentially no RCT support for non-deficiency indications.

What We Don't Know

• Whether Costantini-scale HDT (4 g/d) offers real benefit over placebo in Parkinson's disease (no RCT)
• Whether TTFD specifically offers benefit over thiamine HCl in long COVID / POTS / dysautonomia (no RCT)
• Whether SLC19A2 heterozygous carriers should be screened for T2D (population-level risk confirmed, clinical application unclear)
• Optimal parenteral thiamine regimen for Wernicke prevention (OpTIn data pending full analysis)
• Whether GLP-1 agonist users should routinely supplement thiamine (emerging signal, no framework)
• Whether pediatric HF patients on diuretics benefit from doses >50 mg/d (PMID 41872295 suggests they might)
• Long-term safety of benfotiamine and TTFD at >1 year continuous use at therapeutic doses
• Why high-dose thiamine reduces IBD fatigue (deficiency correction vs pharmacological)
• Whether thiamine's novel mechanisms (TPK1/TFEB, HIF-1α, PPARγ, antiplatelet) translate to any human clinical benefit
• Clinical relevance of thiamine-gut-microbiome-MASLD axis
• Whether there is a meaningful benfotiamine subgroup that still benefits from long-term use post-BOND 2026
• Sulbutiamine dependence mechanism and true prevalence

References

Systematic Reviews / Meta-Analyses

• Wang G et al. (2026) Nutr Clin Pract. PMID: 41277404 — Thiamine in septic shock MA: mortality RR 0.80, RRT RR 0.48.
• Xu X et al. (2026) Clinics. PMID: 41863966 — 9 RCTs, thiamine reduces RRT + lactate + SOFA; mortality only in deficient subgroup.
• Xu M et al. (2022) Complement Ther Med. PMID: 35842069 — Thiamine in HF, 6 RCTs: unclear mortality benefit.
• Puertas-Miranda et al. (2025) Neuroepidemiology. PMID: 40911513 — WE meta, 5,510 patients; classic triad only 32.7%.
• Day E et al. (2013) Cochrane. PMID: 23818100 — Thiamine for WKS; only 2 RCTs identified.
• Rodríguez-Martín JL et al. (2001) Cochrane. PMID: 11405995 — Thiamine for AD: no evidence of benefit.
• Liang B et al. (2023) Crit Care. PMID: 36915173 — Vitamin C MA in sepsis.
• Smith TJ et al. (2021) Ann N Y Acad Sci. PMID: 33305487 — Thiamine deficiency disorders clinical review.
• Gomes F et al. (2021) Ann N Y Acad Sci. PMID: 33576090 — Non-alcoholic B1 deficiency in high-income countries.
• Teixeira et al. (2025) Eur J Intern Med. PMID: 39818490 — B1 cognition in AUD.
• O'Brien (2025) Eur Child Adolesc Psychiatry. PMID: 39240360 — B1 in anorexia nervosa.

Landmark RCTs

• Ziegler D et al. (2026) BOND BMJ Open Diabetes Res Care. PMID: 41571333 — Benfotiamine 600 mg/d × 12 mo: NULL on 13 objective DSPN endpoints despite analyte rise.
• Bager P et al. (2021) Aliment Pharmacol Ther. PMID: 33210299 — Thiamine 600 mg/d reduces IBD fatigue −2.6 pts (p<0.001), N=40.
• Bager P et al. (2022) — extension study. PMID: 34592862.
• Stracke H et al. (2008) BENDIP Exp Clin Endocrinol Diabetes. PMID: 18473286 — Benfotiamine 600 mg/d × 6 wk improved DSPN symptom scores.
• Gibson GE et al. (2020) J Alzheimers Dis. PMID: 33074237 — Benfotiamine in AD Phase IIa: safe but null primary endpoints.
• Xie F et al. (2014) J Clin Pharmacol. PMID: 24399744 — Benfotiamine vs thiamine HCl PK: 3.6× plasma TPP AUC.
• Whitfield KC et al. (2025) Dev Psychol. PMID: 39699595 — Maternal thiamine 10 mg/d → infant language development in Cambodia RCT.
• Sevim S et al. (2017) — Sulbutiamine for MS fatigue. PMID: 28755683.
• Seligmann H et al. (1991) Am J Med. PMID: 1867241 — Thiamine deficiency in HF on furosemide.
• Shimon I et al. (1995) Am J Med. PMID: 7573094 — IV thiamine improves LVEF in deficient HF patients.

Mechanism / Preclinical (2024–2026)

• Zhang SZ et al. (2026) Exp Neurol. PMID: 41506439 — Astrocytic TPK1/TFEB clears Aβ.
• (2026) Neurochem Int. PMID: 41707701 — Thiamine suppresses HIF-1α in Aβ neurotoxicity.
• (2025) Front Pharmacol. PMID: 41368574 — Thiamine as PPARγ ligand.
• Li Q et al. (2026) Life Sci. PMID: 41865870 — TPP antiplatelet via PI3K-Akt/MAPK.
• He N et al. (2026) Adv Sci. PMID: 41560354 — B. virosa TMP attenuates MASLD.
• Sun G et al. (2025) Microbiome. PMID: 41456070 — Gut-thiamine-placental Notch axis.
• (2026) Gut. PMID: 41558814 — Multi-ancestry GWAS: B1 metabolism → gut motility.
• Hammes HP et al. (2003) Nat Med. PMID: 12612547 — Benfotiamine prevents experimental diabetic complications.

Pharmacogenomics / Safety

• Diabetologia (2025) PMID: 40603556 — SLC19A2 het variants → dominant mild hyperglycemia; UKB null variants T2D OR 3.7.
• Zhang E et al. (2025) Int J Biol Macromol. PMID: 41205939 — SLC19A3 structural biology for BTBGD drug design.
• (2026) JPEN. PMID: 41864862 — Drug-induced B1 deficiency pharmacovigilance: 38 drugs flagged.
• (2025) Life Basel. PMID: 41598206 — Thiamine hypersensitivity desensitization protocol.
• McLaughlin et al. (2020) PMID: 31932197; Aldhaeefi et al. (2022) PMID: 35491726 — Modern IV thiamine push safety.

Regulatory / Guidelines

• Thomson AD et al. (2012) Eur J Neurol. PMID: 22540422 — WE management guidelines.
• Thomson AD et al. (2013) Alcohol Alcohol. PMID: 22822077 — WE management UK.
• ESPEN (2022) PMID: 35365361 — Micronutrient guideline.
• ASMBS (2025) PMID: 40345894 — Post-bariatric WE prevention.
• ACOG Bulletin 189 (2018) PMID: 29266076 — Hyperemesis gravidarum thiamine.
• AuSPEN (2025) PMID: 40090863 — Refeeding syndrome.
• Costantini A et al. (2015) — Open-label HDT in PD. PMID: 26505466 — cited for completeness; uncontrolled design.

Observational (2024–2026 MIMIC-IV cluster)

• (2026) Sci Rep. PMID: 41872438 — Sepsis-delirium HR 0.51.
• (2026) BMC Pulm Med. PMID: 41862834 — ARF mortality reduction.
• (2025) BMC Neurol. PMID: 41184785 — Critical cerebrovascular disease.
• (2026) Shock. PMID: 41166064 — High vs low dose in septic shock: null.
• (2026) Sci Rep. PMID: 41872295 — Pediatric HF + diuretics: 25–50 mg insufficient.

Additional Resources

• NIH ODS Thiamin Fact Sheet
• Examine.com Thiamine
• NICE CG100 — Alcohol-use disorder physical complications
• Michael J. Fox Foundation — Thiamine and Parkinson's (explicit non-recommendation of HDT)