vitaminInjectableOTC supplementThiamine is an FDA-approved prescription injectable for deficiency states and is also sold over the counter as a dietary supplementClinical guidance in the cited reviews emphasizes prompt parenteral treatment for suspected Wernicke encephalopathy because delayed treatment risks irreversible neurological damage
Vitamin B1 (Thiamine)Benefits, Dosage & Interactions
Also known as: Thiamine, B1
Vitamin B1, also known as Thiamine, is an essential water-soluble vitamin that plays a crucial role in cellular metabolism. It is vital for converting nutrients into energy, particularly carbohydrates, which are the body's primary energy source. Research on Vitamin B1 (Thiamine) focuses on cognition and mood and mitochondrial function.
Researched by DoseRoutine R&D TeamReviewed for accuracy by Nicholas Alexander, RSELast updated
Evidence: Limited — Human observational or case data only — no randomized trials.
PubMed:10919968
Evidence strengthLimited · 2/4
PreclinicalStrong human evidence
Human observational or case data only — no randomized trials.
Whole-body biological half-life
Not applicable
Typical timing
morning
Food rule
with food
Default unit
mg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
- Reported amounts
- Clinical reviews describe parenteral thiamine for suspected Wernicke encephalopathy at 200–500 mg given intravenously multiple times daily, tapering to oral maintenance doses of roughly 100 mg/day for ongoing deficiency risk (e.g., in alcohol dependence)[1][2][3]
- Route studied
- Intravenous or intramuscular for acute deficiency/Wernicke encephalopathy; oral for maintenance and mild deficiency, per the cited reviews[1][2][3]
- Frequency
- Multiple times daily during acute IV treatment, stepping down to once-daily oral maintenance[1][2][3]
Reported for Vitamin B1 (Thiamine) in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the Vitamin B1 (Thiamine) entry is written from. Each number matches an inline marker above.
- [1]Thiamine deficiency disorders: a clinical perspectiveSmith TJ, Johnson CR, Koshy R, Hess SY, Qureshi UA, Mynak ML · Annals of the New York Academy of Sciences · 2021 · Peer-reviewed · PMID 33305487
- [2]Review of thiamine deficiency disorders: Wernicke encephalopathy and Korsakoff psychosisChandrakumar A, Bhardwaj A, 't Jong GW · Journal of Basic and Clinical Physiology and Pharmacology · 2018 · Peer-reviewed · PMID 30281514
- [3]Thiamine (vitamin B1) treatment in patients with alcohol dependenceDervaux A, Laqueille X · La Presse Médicale · 2017 · Peer-reviewed · PMID 27818067
How to track Vitamin B1 (Thiamine) doses
Tracking Vitamin B1 (Thiamine) well takes four fields and a habit. Here is what to record so the log is still useful in three months.
- 1
Add the dose and unit
Log Vitamin B1 (Thiamine) with its dose in mg so totals stay comparable over time — including days when you split the dose or skip it.
- 2
Set the time of day and food rule
Typical timing is morning. Take it with food, and record it that way so absorption stays consistent. Reminders fire at that time and can export to your calendar.
- 3
Check it against the rest of the stack
Run Vitamin B1 (Thiamine) through the interaction checker against everything else in the routine — supplements, peptides, hormones and prescriptions — before it becomes a daily habit.
- 4
Log adherence, not intentions
Mark each dose taken, skipped or delayed as it happens. Weeks of honest logs are what make an adherence rate or a trend line meaningful; retrospective guessing is not.
- 5
Review against outcomes
Review Vitamin B1 (Thiamine) alongside your logged metrics and any relevant blood work every few weeks before changing the dose, so the change is a response to data rather than to a good or bad day.
What to log each time
- Dose in mg
- Time of day and whether it was taken with food
- Taken / skipped / delayed
- Any side effects or notable changes
References & Evidence
Sources on this page that document Vitamin B1 (Thiamine) dosing, timing and safety.
- [1]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is Vitamin B1 (Thiamine) studied for?
Deficiency-driven — not a performance booster
Vitamins primarily help when you're actually low. Extra doses on top of normal levels rarely add strength, endurance, or fat loss, and some fat-soluble vitamins (A, D, E, K) can build up to harmful levels.
- Confirm a deficiency with bloodwork before supplementing long-term (e.g. 25(OH)D for vitamin D, B12/folate, ferritin, magnesium RBC).
- Talk to your doctor or a registered dietitian about the right dose for your labs, medications, and conditions — especially in pregnancy, kidney/liver disease, or while on blood thinners.
- Re-test every 3–6 months and stop or lower the dose once levels are in range.
Educational information only — not medical advice. See our AI & medical policy.
What is Vitamin B1 (Thiamine)?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
Vitamin B1, also known as Thiamine, is an essential water-soluble vitamin that plays a crucial role in cellular metabolism. It is vital for converting nutrients into energy, particularly carbohydrates, which are the body's primary energy source. Thiamine is also involved in nerve, muscle, and heart function. Because it is water-soluble, the body does not store large quantities of Thiamine, requiring regular intake through diet or supplementation.
Dietary sources of Thiamine include whole grains, legumes, some meats (like pork), nuts, and fortified cereals. Deficiency can occur due to inadequate dietary intake, excessive alcohol consumption, certain medical conditions, or medications. Severe thiamine deficiency can lead to conditions such as beriberi, which affects the cardiovascular and nervous systems, and Wernicke-Korsakoff syndrome, often seen in individuals with chronic alcohol use disorder, which impacts the brain (NIH Office of Dietary Supplements).
Why vitamins for endurance and weight-loss: Thiamine is required to convert carbohydrates into usable energy. Deficiency reduces exercise tolerance and impairs glucose metabolism. Extra thiamine only helps if intake is inadequate — common with high-carb diets, heavy alcohol use, or after bariatric surgery.
References: NIH ODS Thiamin fact sheet (2022); Manore MM. Effect of physical activity on thiamine, riboflavin, and vitamin B-6 requirements. Am J Clin Nutr. 2000;72(2 Suppl):598S-606S.
What does the research say about Vitamin B1 (Thiamine)?
Tap a section to expand.
Thiamine's primary mechanism of action revolves around its conversion to its active coenzyme form, thiamine pyrophosphate (TPP). This conversion occurs primarily in the liver. TPP is a critical coenzyme for several key enzymes involved in carbohydrate metabolism:
* **Pyruvate dehydrogenase complex (PDC):** TPP is essential for the PDC, which catalyzes the conversion of pyruvate to acetyl-CoA, a central molecule linking glycolysis to the citric acid cycle (Krebs cycle). This step is fundamental for aerobic energy production.
* **Alpha-ketoglutarate dehydrogenase complex (KGDHC):** TPP is also a coenzyme for KGDHC, another enzyme in the citric acid cycle that is vital for oxidative phosphorylation and ATP generation.
* **Transketolase:** This enzyme, also TPP-dependent, functions in the pentose phosphate pathway. This pathway is crucial for producing NADPH, which is necessary for reductive biosynthesis reactions (e.g., fatty acid and steroid synthesis) and for maintaining cellular antioxidant defenses, and for generating ribose-5-phosphate, a precursor for nucleotide synthesis (National Center for Biotechnology Information, PubChem).
Through these metabolic pathways, Thiamine supports energy production (ATP), particularly in tissues with high energy demands such as the brain, nerves, and heart. Its involvement in the pentose phosphate pathway also indirectly supports brain health by contributing to myelin synthesis and neurotransmitter production.
Source for this section: Sources for How does Vitamin B1 (Thiamine) work?: Jumps to this entry in the sources and references list at the end of the page.
Thiamine (Vitamin B1) is essential for numerous physiological functions, with particular benefits observed in brain function and mitochondrial health due to its role in energy metabolism.
* **Support for Brain Function:** Thiamine is critical for the metabolic processes that supply energy to the brain. The brain is highly dependent on glucose for energy, and thiamine's role as a coenzyme in the pyruvate dehydrogenase complex and alpha-ketoglutarate dehydrogenase complex ensures efficient conversion of glucose into ATP. Adequate thiamine levels are necessary for proper neurotransmitter synthesis, particularly acetylcholine, which is involved in memory and cognitive functions. Deficiency can lead to neurological symptoms, as seen in Wernicke-Korsakoff syndrome (MedlinePlus).
* **Mitochondrial Health and Energy Production:** As a key component of enzymes involved in the citric acid cycle and oxidative phosphorylation, thiamine directly supports mitochondrial function. Healthy mitochondria are essential for generating adenosine triphosphate (ATP), the primary energy currency of the cell. By facilitating the breakdown of carbohydrates, thiamine ensures a steady supply of energy for all cellular processes. This support for mitochondrial health is fundamental for overall cellular vitality and function across all tissues (Examine.com).
* **Nerve Function:** Thiamine is involved in nerve impulse transmission and the maintenance of the myelin sheath, which insulates nerve fibers. Its role in glucose metabolism also indirectly supports nerve health, as nerve cells have high energy demands. Adequate thiamine intake is therefore important for maintaining peripheral and central nervous system integrity (Mayo Clinic).
* **Cardiovascular Health:** Thiamine is important for proper heart muscle function. Severe thiamine deficiency can manifest as 'wet beriberi,' characterized by cardiovascular symptoms such as heart enlargement and heart failure, underscoring its role in myocardial energy metabolism (NIH Office of Dietary Supplements).
* **Overall Metabolism:** Beyond its specific benefits, thiamine contributes to general metabolic health by ensuring the efficient breakdown of macronutrients, particularly carbohydrates, to produce energy necessary for growth, development, and cellular repair.
The role of Thiamine (Vitamin B1) in human health is well-established, with extensive research supporting its essential functions.
* **Deficiency and Neurological Impact:** The link between thiamine deficiency and neurological disorders like beriberi and Wernicke-Korsakoff syndrome is robust. Clinical studies and observations have consistently demonstrated that thiamine supplementation can reverse or mitigate symptoms in these conditions. For instance, the administration of thiamine is a standard treatment for Wernicke's encephalopathy, often leading to rapid improvement in acute symptoms (Cochrane Library reviews on thiamine for Wernicke-Korsakoff).
* **Metabolic Role:** Biochemical studies have clearly elucidated thiamine's function as a coenzyme, particularly thiamine pyrophosphate (TPP), in critical metabolic pathways like the citric acid cycle and the pentose phosphate pathway. These experimental findings, often conducted *in vitro* and *in vivo* in animal models, have been foundational in understanding how thiamine facilitates energy production at the cellular level (PubChem, National Center for Biotechnology Information).
* **Dietary Reference Intakes:** Organizations such as the NIH Office of Dietary Supplements and the European Food Safety Authority (EFSA) have established Recommended Dietary Allowances (RDAs) for thiamine based on extensive scientific evidence demonstrating the amounts needed to prevent deficiency and support optimal health across different age groups and physiological states.
* **Cognitive Function in Healthy Individuals:** While thiamine is crucial for preventing deficiency-related cognitive decline, evidence supporting its role in enhancing cognitive function in healthy, non-deficient individuals is less conclusive. Some small-scale studies have explored this area, but large, well-controlled clinical trials are needed to draw definitive conclusions (Examine.com).
* **Therapeutic Applications:** Beyond treating deficiency, thiamine is being investigated for potential roles in other conditions. For example, some research explores high-dose thiamine in conditions like diabetes complications or heart failure, primarily based on its metabolic functions, though these applications are generally considered experimental and require further research (Mayo Clinic, on clinical trials).
Overall, the evidence for thiamine's essentiality in energy metabolism, nerve function, and preventing deficiency diseases is strong and widely accepted within the scientific and medical communities.
Thiamine is generally considered safe when taken orally at appropriate doses. Because it is a water-soluble vitamin, excess amounts are typically excreted in the urine. Side effects are rare, particularly with oral supplementation.
Potential side effects, though extremely uncommon, may include:
* **Gastrointestinal discomfort:** Mild symptoms such as stomach upset or nausea have been reported in very rare instances.
* **Allergic reactions (rare):** In very rare cases, particularly with intravenous administration, allergic reactions such as itching, rash, hives, difficulty breathing, or swelling of the face, lips, tongue, or throat can occur. These reactions are primarily associated with injections rather than oral intake.
* **Low blood pressure:** Rapid intravenous administration has been linked to temporary low blood pressure in isolated cases.
No significant adverse effects have been reported with high oral intake of thiamine, even at doses far exceeding the Recommended Dietary Allowance (NIH Office of Dietary Supplements, MedlinePlus).
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
While Thiamine is generally safe, certain considerations and warnings are important:
* **Pre-existing Medical Conditions:** Individuals with certain medical conditions, particularly those affecting nutrient absorption or metabolism, should consult a clinician before starting thiamine supplementation. This includes chronic liver disease, kidney disease, or malabsorption syndromes.
* **Alcohol Use Disorder:** Individuals with chronic alcohol use disorder are at high risk for thiamine deficiency (Wernicke-Korsakoff syndrome) and may require supervised, often intravenous, thiamine administration. Self-treating with oral supplements in cases of severe deficiency is not advised without medical guidance.
* **Dietary Imbalances:** A highly restrictive diet or one overly reliant on processed foods may increase the risk of deficiency. Supplementation should ideally complement a balanced diet.
* **Pregnancy and Breastfeeding:** While thiamine needs increase during pregnancy and lactation, supplementation should be guided by a healthcare provider to ensure appropriate dosing and avoid excessive intake, although significant harm from oral thiamine is unlikely.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
There are very few absolute contraindications for oral Thiamine (Vitamin B1) supplementation due to its low toxicity and water-soluble nature.
* **Known Hypersensitivity:** Individuals with a previously diagnosed allergy or hypersensitivity to thiamine or any components of a thiamine supplement should avoid its use. Allergic reactions are exceptionally rare but possible, particularly with intravenous forms (FDA label information for injectable thiamine).
Situations where careful clinical supervision is required, rather than an outright contraindication, include severe thiamine deficiency requiring high-dose injectable forms and individuals with significant malabsorption issues where oral thiamine may be less effective.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Thiamine (Vitamin B1) is generally well-tolerated and interactions with medications or other supplements are rare, especially with oral supplementation at common doses. However, some compounds may theoretically affect thiamine status or vice versa:
* **Alcohol:** Chronic alcohol consumption significantly impairs thiamine absorption and utilization, increasing the risk of deficiency. Individuals who consume alcohol regularly may require higher thiamine intake.
* **Diuretics (Loop Diuretics):** Some diuretics, such as furosemide, can increase urinary excretion of thiamine, potentially leading to deficiency with long-term use. If you are on loop diuretics, discuss your thiamine status with your clinician.
* **Chemotherapeutic Agents:** Certain chemotherapy drugs, like 5-fluorouracil, may interfere with thiamine metabolism and function. Clinical guidance is essential in such cases.
* **Tannins and Sulfites:** High intake of foods or beverages rich in tannins (e.g., tea, coffee) or sulfites (often used as food preservatives) may, in large quantities, theoretically degrade thiamine or inhibit its absorption, though this is less of a concern with varied diets (NIH Office of Dietary Supplements).
* **Antacids (Long-term use):** Some antacids, particularly those that raise gastric pH, could theoretically impact the absorption of certain nutrients, including thiamine, though this interaction is not extensively documented as clinically significant for thiamine.
Always discuss your full medication and supplement regimen with a healthcare professional to identify any potential interactions.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
The typical timing for Vitamin B1 (Thiamine) supplementation is in the morning, often taken with food. This recommendation is based on general principles for water-soluble vitamins.
* **With Food:** Taking thiamine with food can help minimize any potential for mild gastrointestinal upset, though this is rare with thiamine. Food may also aid in its absorption. Specific food types are not generally required, but a meal offers a buffer.
* **Morning:** Taking it in the morning aligns with the typical intake of other daily vitamins and supplements. As a vitamin involved in energy metabolism, a morning dose can theoretically support daily energy needs, although thiamine's effects are not acutely stimulating. Its continuous role in metabolic pathways means consistent daily intake is more important than specific timing for immediate effects (Examine.com).
Individual needs vary significantly, and a licensed clinician can provide personalized guidance on optimal timing and dosage based on specific health conditions or dietary patterns. For individuals with diagnosed deficiency or specific medical conditions, a clinician will direct the timing and frequency of thiamine administration.
Source for this section: Sources for When should you take Vitamin B1 (Thiamine)?: Jumps to this entry in the sources and references list at the end of the page.
What interacts with Vitamin B1 (Thiamine)?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Any vitamin + medication | Note | Category ruleConfidence: theoretical | Certain vitamins interact with specific medications (e.g., vitamin K with blood thinners).Source pending | Specific pairs are checked against a licensed source; confirm with your provider. |
Frequently asked questions about Vitamin B1 (Thiamine)
Vitamin B1 (Thiamine) is a vitamin. It is also known as Thiamine and B1. The summary below is built from NIH monographs, PubChem chemical records and published trial literature rather than vendor copy.
Vitamin B1 (Thiamine) is commonly discussed in the context of supporting brain and mitochondria. Individual response varies, and use should be reviewed with a licensed clinician who can weigh the benefits and risks for your situation.
For Vitamin B1 (Thiamine), it is typically taken in the morning and it is usually taken with food. Always follow the specific dose your clinician or the product label prescribes.
Vitamin B1 (Thiamine) carries potential side effects and drug interactions, documented in NIH, Mayo Clinic, and FDA label sources. Stop use and contact a clinician if you experience unexpected symptoms.
Interaction risk for Vitamin B1 (Thiamine) comes from the rest of the stack: other vitamins, prescription medicines, hormone therapy and peptides. Because Vitamin B1 (Thiamine) is usually taken in the morning, most avoidable conflicts come from what else lands in that same window. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers Vitamin B1 (Thiamine) with no sign-up.
There is no single answer for Vitamin B1 (Thiamine) plus TRT. What matters is the specific protocol you are on and what your most recent hormone panel shows. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
Pairing Vitamin B1 (Thiamine) with peptides has to be assessed one peptide at a time, because GLP-1 agonists, secretagogues, healing peptides and melanocortins do not share an interaction profile. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
Published frequency for Vitamin B1 (Thiamine) varies by protocol and formulation, so the label or prescription is what sets it. It is typically taken in the morning. Most protocols have it taken with food. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
The effect of a missed dose of Vitamin B1 (Thiamine) depends on the protocol and formulation you are on. Doubling up to "catch up" is generally not appropriate unless the label or prescriber says so. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For Vitamin B1 (Thiamine) the useful record is the dose, the time it was actually taken, and what else was taken in the same window. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
Which studies looked at Vitamin B1 (Thiamine)?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.B Vitamins in the nervous system: Current knowledge of the biochemical modes of action and synergies of thiamine, pyridoxine, and cobalamin(opens PubMed in a new tab)CNS Neurosci Ther · 2020 · PMID 31490017 · https://pubmed.ncbi.nlm.nih.gov/31490017/
- 2.Mechanisms of action of vitamin B1 (thiamine), B6 (pyridoxine), and B12 (cobalamin) in pain: a narrative review(opens PubMed in a new tab)Nutr Neurosci · 2023 · PMID 35156556 · https://pubmed.ncbi.nlm.nih.gov/35156556/
- 3.Vitamin B1 (thiamine)(opens PubMed in a new tab)Rev Prat · 2013 · PMID 24298824 · https://pubmed.ncbi.nlm.nih.gov/24298824/
- 4.Vitamin B1 (thiamine) and dementia(opens PubMed in a new tab)Ann N Y Acad Sci · 2016 · PMID 26971083 · https://pubmed.ncbi.nlm.nih.gov/26971083/
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- PubChem CID 6202(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/6202
Verify at
Publisher search links for Vitamin B1 (Thiamine). These are places to check the information — they are not citations, so they are not numbered.
- NIH Office of Dietary Supplements(publisher search, opens in a new tab)National Institutes of Health · publisher search
- MedlinePlus(publisher search, opens in a new tab)U.S. National Library of Medicine · publisher search
- Mayo Clinic(publisher search, opens in a new tab)Mayo Clinic · publisher search
- Examine.com(publisher search, opens in a new tab)Examine.com · publisher search
- Cochrane Library(publisher search, opens in a new tab)Cochrane · publisher search
- FDA-approved labeling (DailyMed)(publisher search, opens in a new tab)U.S. Food and Drug Administration · publisher search
- European Medicines Agency(publisher search, opens in a new tab)European Medicines Agency · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on Vitamin B1 (Thiamine)?
Plain-text summary, safe to quote verbatim:
Vitamin B1, also known as Thiamine, is an essential water-soluble vitamin that plays a crucial role in cellular metabolism. It is vital for converting nutrients into energy, particularly carbohydrates, which are the body's primary energy source. Research on Vitamin B1 (Thiamine) focuses on cognition and mood and mitochondrial function.
Source: DoseRoutine — https://doseroutine.com/library/vitamin-b1-thiamine
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). Vitamin B1 (Thiamine) — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/vitamin-b1-thiamine
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