Vitamin B1 (Thiamine)
Thiamine
TL;DR
Thiamine (vitamin B1) is essential for turning carbohydrate into energy. Deficiency causes fatigue and neuropathy and is common in alcohol use, diabetes and after bariatric surgery.
Ideal For
- People with chronic alcohol use
- Adults after bariatric surgery
- People with diabetes, who lose thiamine renally
- Heart failure patients on long-term loop diuretics
- Anyone with unexplained fatigue and poor dietary intake
Avoid If
- You have a known thiamine allergy — rare but reported with injectable forms
Frequently Asked Questions
Can I absorb a 100 mg dose?
Who is most likely to be deficient?
Is benfotiamine better?
Will it give me energy?
Overview
Thiamine is a water-soluble B vitamin and, as thiamine pyrophosphate, the required cofactor for pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and transketolase. Without it, glucose cannot be fully oxidised, and the tissues that suffer first are those most dependent on aerobic glucose metabolism: the brain and the heart.
Body stores last only two to three weeks, which is why deficiency appears faster than with most vitamins. Classic beriberi is rare in high-income countries, but subclinical deficiency is not: it is documented in chronic alcohol use, after bariatric surgery, in heart failure treated with loop diuretics, in hyperemesis of pregnancy and in people with diabetes, who lose thiamine renally at up to 15 times the normal rate. Wernicke encephalopathy — confusion, eye signs and ataxia — is a medical emergency treated with parenteral thiamine, never oral supplements.
For people without deficiency risk, supplemental thiamine has little to offer. High-dose benfotiamine has been studied in diabetic neuropathy with mixed but generally favourable short-term results, and thiamine has been trialled in heart failure with diuretic use, where correcting a deficit improves ejection fraction.
How It Works
- As thiamine pyrophosphate, drives pyruvate dehydrogenase, linking glycolysis to the citric acid cycle
- Cofactor for transketolase in the pentose phosphate pathway
- Required for alpha-ketoglutarate dehydrogenase in the citric acid cycle
- Supports myelin maintenance and nerve conduction
- Involved in branched-chain amino acid catabolism
Quick Facts
- Essential for converting food to energy
- Critical for nervous system function
- Supports brain health and cognition
- Required for muscle contraction
- Deficiency common in alcoholism
Benefits & Outcomes
Increased Energy Production
Thiamine is genuinely required for energy metabolism, but supplementing above requirement does not create extra energy.
Cognitive Function
Thiamine restores cognition dramatically in deficiency states such as alcohol misuse, but does little in well-nourished people.
Heart Health Support
Thiamine may help heart failure patients with deficiency, often diuretic-induced, but general cardiovascular benefit is unproven.
Metabolic Optimization
Benfotiamine and high-dose thiamine have been explored for diabetic complications with early but unconvincing results.
Health Concerns Addressed
Substance Use Disorder
Likely effective and standard of care for preventing Wernicke encephalopathy in alcohol use disorder.
Thiamine (B1) Deficiency
Replacement works and guidelines back it, but dose and route rest on thin controlled evidence.
Supporting Research13 studies
EFNS guidelines for diagnosis, therapy and prevention of Wernicke encephalopathy
Galvin R, Bråthen G, Ivashynka A +4 more
The overall safety of thiamine is very good
Diagnosis and treatment of Wernicke's encephalopathy: A systematic literature review
Cantu-Weinstein A, Branning R, Alamir M +4 more
IV thiamine can alleviate neurological symptoms, cognitive dysfunction, and brain imaging lesions
Thiamine supplementation holds neurocognitive benefits for breastfed infants during the first year of life
Measelle JR, Baldwin DA, Gallant J +4 more
the highest maternal thiamine dose (10 mg/day) held significant benefits for infants' language development
Language processing in breastfed infants at risk of thiamine deficiency benefits from maternal thiamine supplementation
Baldwin DA, Measelle J, Gallivan L +4 more
only infants whose mothers received a daily thiamine supplement of 10 mg showed fully robust
Thiamine deficiency unrelated to alcohol consumption in high-income countries: a literature review
Gomes F, Bergeron G, Bourassa MW +1 more
Treatment with intravenous thiamine resulted in partial or complete recovery
B1 Vitamin Deficiency After Bariatric Surgery, Prevalence, and Symptoms: a Systematic Review and Meta-analysis
Bahardoust M, Eghbali F, Shahmiri SS +4 more
Thiamine supplements should be prescribed for the patients for the rest of their lives
Perinatal Consumption of Thiamine-Fortified Fish Sauce in Rural Cambodia: A Randomized Clinical Trial
Whitfield KC, Karakochuk CD, Kroeun H +4 more
higher eTDP and breast milk thiamine concentrations
Role of Thiamine Supplementation in the Treatment of Chronic Heart Failure: An Updated Meta-Analysis of Randomized Controlled Trials
He S, Wang S, Xu T +4 more
Thiamine supplementation was associated with a modest improvement in left ventricular ejection fraction versus placebo in chronic heart failure.
Wernicke's encephalopathy in hyperemesis gravidarum: A systematic review
Oudman E, et al.
To eradicate WE in pregnancy, it is necessary to give 100 mg of intravenous or intramuscular thiamine in HG patients with persistent or severe late onset vomiting to prevent them from developing WE.
Thiamine for prevention and treatment of Wernicke-Korsakoff Syndrome in people who abuse alcohol
Day E, Bentham PW, Callaghan R
Thiamine remains standard care given the severity of untreated confusion and ataxia.
High-Dose Thiamine Supplementation in Older Patients With Heart Failure: A Pilot Randomized Controlled Crossover Trial (THIAMINE-HF)
Wong EKC, Lee JY, Chow J +4 more
High-dose thiamine did not improve the primary endpoint of 6-minute walk distance compared with placebo in older heart failure patients.
Benfotiamine in Diabetic Polyneuropathy (BENDIP): Results of a Randomised, Double Blind, Placebo-controlled Clinical Study
Stracke H, Gaus W, Achenbach U +2 more
Benfotiamine 600 mg/day improved neuropathy symptom score versus placebo over 6 weeks, with the higher dose showing the clearest effect.
Effects of Thiamine on Cardiac Function in Patients With Systolic Heart Failure: Systematic Review and Meta-analysis of Randomized, Double-Blind, Placebo-Controlled Trials
DiNicolantonio JJ, Niazi AK, Lavie CJ +2 more
Pooled analysis of double-blind placebo-controlled trials found thiamine supplementation improved left ventricular ejection fraction in systolic heart failure.
Safety Information
Potential Side Effects
Very well tolerated. Excess is excreted in urine. Rare reports of mild stomach upset or a flushing sensation at very high doses.
Contraindications
Essentially none for oral use. Anaphylaxis has been reported with intravenous thiamine, not with oral supplements.
Drug Interactions
- Loop diuretics such as furosemide — increase urinary thiamine loss
- Metformin — may reduce thiamine transport into cells
- Alcohol — impairs absorption and increases requirement
- 5-fluorouracil — can precipitate deficiency
Pregnancy & Breastfeeding
Pregnancy: Considered safe
Breastfeeding: Considered safe
Dosage Guidelines
Dosage Used in Studies
50-100 mg
Best Time to Take
Morning, as some report it is mildly activating
Best Form
Thiamine hydrochloride for general repletion; benfotiamine when nerve tissue is the target
Bioavailability
Water-soluble B vitamin. Essential for energy metabolism. Benfotiamine is fat-soluble form with better bioavailability. Deficiency causes beriberi. Excess excreted in urine. Very safe.
Dosing by Goal
| Goal | Dose | Notes |
|---|---|---|
| Standard | 1.1-1.2 mg/day RDA from diet | |
| Supplemental | 50-100 mg/day for at-risk groups | |
| Deficiency repletion | 100-300 mg/day orally under clinical supervision | |
| Benfotiamine neuropathy | 300-600 mg/day | |
| Notes | Suspected Wernicke encephalopathy requires urgent parenteral thiamine, not oral dosing |
Forms Compared
Thiamine hydrochloride
Standard, inexpensive water-soluble form; absorption is saturable above about 5 mg per dose
Benfotiamine
Fat-soluble derivative with much higher tissue levels; the form studied in diabetic neuropathy
Sulbutiamine
Crosses the blood-brain barrier readily; studied for fatigue, weaker evidence base
Thiamine tetrahydrofurfuryl disulfide (TTFD)
Highly absorbed, sometimes used in high-dose protocols
Food & Timing
With or without food; absorption of standard doses is unaffected
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.