MedlinePlus Herbs and Supplements: Thiamin (thiamine), vitamin B1

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Thiamin (thiamine), vitamin B1

Contents of this page:
Background Synonyms Evidence Dosing	Safety Interactions Methodology Selected references

Thiamin, vitamin B1

BackgroundReturn to top

Thiamin (also spelled "thiamine") is a water-soluble B-complex vitamin, previously known as vitamin B1 or aneurine. Thiamin was isolated and characterized in the 1920s, and thus was one of the first organic compounds to be recognized as a vitamin.

Thiamin is involved in numerous body functions, including: nervous system and muscle functioning; flow of electrolytes in and out of nerve and muscle cells (through ion channels); multiple enzyme processes (via the coenzyme thiamin pyrophosphate); carbohydrate metabolism; and production of hydrochloric acid (which is necessary for proper digestion). Because there is very little thiamin stored in the body, depletion can occur as quickly as within 14 days.

Severe chronic thiamin deficiency (beriberi) can result in potentially serious complications involving the nervous system/brain, muscles, heart, and gastrointestinal system.

Dietary sources of thiamin include beef, brewer's yeast, legumes (beans, lentils), milk, nuts, oats, oranges, pork, rice, seeds, wheat, whole grain cereals, and yeast. In industrialized countries, foods made with white rice or white flour are often fortified with thiamin (because most of the naturally occurring thiamin is lost during the refinement process).

SynonymsReturn to top

Aneurine, aneurine HCL, aneurine mononitrate, antiberiberi factor, antiberiberi vitamin, antineuritic factor, antineuritic vitamin, anurine, B complex vitamin, beta-hydroxy-ethylthiazolium chloride, thiamin, thiamin chloride, thiamin diphosphate, thiamin HCL, thiamin hydrochloride, thiamin monophosphate (TMP), thiamin nitrate, thiamin pyrophosphate (TPP), thiamin triphosphate (TTP), thiamine, thiamine chloride, thiaminium chloride HCL, thiaminium chloride hydrochloride.

EvidenceReturn to top

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence	Grade^*
Metabolic disorders (subacute necrotizing encephalopathy, maple syrup urine disease, pyruvate carboxylase deficiency, hyperalaninemia) Taking thiamin by mouth helps to temporarily correct some complications of metabolic disorders associated with genetic diseases including subacute necrotizing encephalopathy (SNE, Leigh's disease), maple syrup urine disease (branched-chain aminoacidopathy), and lactic acidosis associated with pyruvate carboxylase deficiency and hyperalaninemia. Long-term management should be under strict medical supervision.	A
Thiamin deficiency (beriberi, Wernicke's encephalopathy, Korsakoff's psychosis, Wernicke-Korsakoff syndrome) Humans are dependent on dietary intake to fulfill their thiamin requirements. Because there is very little thiamin stored in the body, depletion can occur as quickly as within 14 days. Severe chronic thiamin deficiency can result in potentially serious complications involving the nervous system/brain, muscles, heart, and gastrointestinal system. Patients with thiamin deficiency or related conditions should receive supplemental thiamin under medical supervision.	A
Acute alcohol withdrawal Patients with chronic alcoholism or experiencing alcohol withdrawal are at risk of thiamin deficiency and its associated complications and should be administered thiamin.	B
Total parenteral nutrition (TPN) Thiamin should be added to TPN formulations for patients who are unable to receive thiamin through other sources (such as a multivitamin) for more than seven days.	B
Alzheimer's disease Because thiamin deficiency can result in a form of dementia (Wernicke-Korsakoff syndrome), its relationship to Alzheimer's disease and other forms of dementia has been investigated. Whether thiamin supplementation is of benefit in Alzheimer's disease remains controversial. Further evidence is necessary before a firm conclusion can be reached.	C
Atherosclerosis (prevention in patients with acute hyperglycemia, impaired glucose tolerance (IGT), and diabetes mellitus) Patients with diabetes are at risk of developing hardened arteries (called atherosclerosis). This happens when cholesterol and other substances build up and clog the arteries. Thiamin has been studied as a way to help widen arteries that are too narrow. Regular intake of thiamin might help slow the progression of atherosclerosis. However, additional research is needed.	C
Athletic performance There is inconclusive scientific evidence in this area.	C
Cancer Thiamin deficiency has been observed in some cancer patients, possibly due to increased metabolic needs. It is not clear if lowered levels of thiamin in such patients may actually be adaptive (beneficial). Currently, it remains unclear if thiamin supplementation plays a role in the management of any particular type(s) of cancer.	C
Cataract prevention Preliminary evidence suggests that high dietary thiamin intake may be associated with a decreased risk of cataracts. Further evidence is necessary before a firm conclusion can be reached.	C
Coma/hypothermia of unknown origin Administration of thiamin is often recommended in patients with coma or hypothermia of unknown origin, due to the possible diagnosis of Wernicke's encephalopathy.	C
Crohn's disease Decreased serum thiamine levels have been reported in patients with Crohn's disease. It is not clear if routine thiamin supplementation is beneficial in such patients generally.	C
Didmoad (Wolfram) syndrome Didmoad (Wolfram) syndrome is a rare autosomal recessive inherited disease that results in diabetes mellitus, optic atrophy, diabetes insipidus, sensorineural deafness, and occasionally megaloblastic anemia. The defect is believed to cause a decrease in the enzyme that converts thiamin to its active form. Management, including thiamin supplementation, should be under strict medical supervision.	C
Heart failure (cardiomyopathy) Chronic severe thiamin deficiency can cause heart failure (wet beriberi), a condition that merits thiamin supplementation. It is not clear that thiamin supplementation is beneficial in patients with heart failure due to other causes. However, it is reasonable for patients with heart failure to take a daily multivitamin including thiamin, because some of these individuals may be thiamin deficient. Diuretics may lower thiamin levels. Since diuretics are commonly administered to patients with heart failure, patients taking diuretics are at an increased risk of thiamin deficiency. This area remains controversial, and further evidence is necessary before a firm conclusion can be reached.	C
Leg cramps (during pregnancy) Vitamin B supplements have been used to treat leg cramps during pregnancy. However, additional studies are needed to determine if it is effective.	C
Pyruvate dehydrogenase deficiency (PDH) There is preliminary evidence of clinical improvements in children with PDH following thiamin administration. Further evidence is necessary before a firm conclusion can be reached.	C
Subclinical thiamin deficiency in the elderly While typically asymptomatic, the elderly have been found to have lower thiamin concentrations than younger people. There is limited evidence that thiamin supplementation may be beneficial in individuals with persistently low thiamin blood levels. Further study is necessary before a firm conclusion can be formed in this area.	C
Fractures (hip) Preliminary evidence shows that supplemental thiamin is not beneficial for hip fractures.	D

*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.

Grading rationale

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Age-related lens opacification, Bell's palsy, brain damage (ifosfamide-induced encephalopathy), canker sores, chronic diarrhea, circulation improvement, depression, diabetes, diabetic nephropathy, dysmenorrhea (painful menstruation), epilepsy, erectile dysfunction, fibromyalgia, gastrointestinal disorders, high blood pressure, HIV support, insect repellant, learning, loss of appetite, low back pain, megaloblastic anemia, memory enhancement, myelodysplastic syndrome, optic nerve dysfunction (optic neuropathy), multiple sclerosis, radiation-induced damage (protection from genetic changes), tissue healing after surgery, ulcerative colitis.

DosingReturn to top

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

The U.S. Recommended Daily Allowance (RDA) for adults ages 19 years and older is 1.2 milligrams daily for males and 1.1 milligrams daily for females, taken by mouth. The RDA for pregnant or breastfeeding women of any age is 1.4 milligrams daily, taken by mouth. As a dietary supplement in adults, 1-2 milligrams daily is sometimes used. Thiamin is also used to treat thiamin deficiency, metabolic/genetic enzyme deficiency disorders, neuropathy, and Wernicke's encephalopathy (prevention/treatment) under medical supervision.

Children (younger than 18 years)

The Adequate Intake (AI) for infants ages 0-6 months is 0.2 milligram; for infants 7-12 months the AI is 0.3 milligram; for children 1-3 years the U.S. Recommended Daily Allowance (RDA) is 0.5 milligram; for children 4-8 years the RDA is 0.6 milligram; for children ages 9-13 years the RDA is 0.9 milligram; for males ages 14-18 years the RDA is 1.2 milligram; and for females ages 14-18 years the RDA is 1 milligram, taken by mouth. The RDA for pregnant or breastfeeding women of any age is 1.4 milligrams daily, taken by mouth. Thiamin is also used to treat thiamin deficiency/beriberi under medical supervision.

SafetyReturn to top

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Rare hypersensitivity/allergic reactions have occurred with thiamin supplementation. A small number of life-threatening anaphylactic reactions have been observed with large parenteral (intravenous, intramuscular, subcutaneous) doses of thiamin, generally after multiple doses.

Skin irritation, burning, or itching may rarely occur at injection sites.

Contact dermatitis may occur with occupational exposure and may cause sensitization and lead to dermatitis-type reactions after subsequent oral or injected administrations.

Side Effects and Warnings

Thiamin is generally considered safe and relatively nontoxic, even at high doses. No clear tolerable upper level (UL) of intake has been established. Dermatitis or more serious hypersensitivity reactions occur rarely.

Large doses may cause drowsiness or muscle relaxation.

Injections of thiamin may cause burning. Reactions can often be avoided by slow administration into larger veins.

Pregnancy and Breastfeeding

U.S. Food and Drug Administration Pregnancy Category: C.

InteractionsReturn to top

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

Reduced levels of thiamin in blood and cerebrospinal fluid have been reported in individuals taking phenytoin (Dilantin®) for extended periods of time.

Antacids may lower thiamin levels in the body by decreasing absorption and increasing excretion or metabolism.

Barbiturates may lower thiamin levels in the body by decreasing absorption and increasing excretion or metabolism.

Loop diuretics, particularly furosemide (Lasix®), have been associated with decreased thiamin levels in the body by increasing urinary excretion (and possibly by decreasing absorption and increasing metabolism). Examples of other loop diuretics include bumetanide (Bumex®), ethacrynic acid (Edecrine®), and torsemide (Demadex®). Theoretically, this effect may also occur with other types of diuretics, including thiazide diuretics such as chlorothiazide (Diuril®), chlorthalidone (Hygroton®, Thalidone®), hydrochlorothiazide (HCTZ, Esidrix®, HydroDIURIL®, Ortec®, Microzide®), indapamide (Lozol®), and metolazone (Zaroxolyn®), or potassium-sparing diuretics, such as amiloride (Midamor®), spironolactone (Aldactone®), and triamterene (Dyrenium®). Effects may be most pronounced with larger doses taken over extended periods of time.

Tobacco use decreases thiamin absorption and may lead to decreased levels in the body.

Effects of neuromuscular blocking agents (NMBAs) may be enhanced with concomitant (simultaneous) use of thiamin.

Some antibiotics destroy gastrointestinal flora (normal bacteria in the gut), which manufacture some B vitamins. In theory, this may decrease the amount of thiamin available to humans, although the majority of thiamin is obtained through the diet (not via bacterial production).

Oral contraceptives (birth control pills/OCPS) may decrease levels of some B vitamins, vitamin C, and zinc in the body.

People receiving fluorouracil-containing chemotherapy regimens may be at risk for developing symptoms and signs of thiamin deficiency.

In theory, metformin may reduce thiamine activity, and based on animal research, taking thiamin and metformin together may contribute to the risk of lactic acidosis.

Thiamin has been shown to improve vasodilation (the widening of blood vessels) in patients with high blood sugar levels or diabetes. This response was not seen in patients with normal blood sugar levels. Therefore, thiamin may increase the effects of vasodilators in these patients.

Interactions with Herbs and Dietary Supplements

Consumption of betel nuts ( Areca catechu L.) may reduce thiamine activity due to chemical inactivation, and may lead to symptoms and signs of thiamin deficiency.

Horsetail ( Equisetum arvense L.) contains a thiaminase-like compound that can destroy thiamine in the stomach and theoretically causes symptomatic thiamine deficiency. Horsetail products are available without this property and, for example, the Canadian government requires that horsetail products be certified free of thiaminase activity.

In theory, diuretic herbs may decrease thiamin levels in the body by increasing urinary excretion.

Methodology Return to top

This information is based on a systematic review of scientific literature, edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): Ethan Basch, MD, MSc, MPhil (Memorial Sloan-Kettering Cancer Center); Dawn Costa, BA, BS (Natural Standard Research Collaboration); Shaina Tanguay-Colucci, BS (Natural Standard Research Collaboration): Catherine Ulbricht, PharmD (Massachusetts General Hospital); Christine Ulbricht, BS (University of Massachusetts); Wendy Weissner, BA (Natural Standard Research Collaboration); Jen Woods, BS (Natural Standard Research Collaboration).

Methodology details

Selected references Return to top

Anon. From the Centers for Disease Control and Prevention. Lactic acidosis traced to thiamine deficiency related to nationwide shortage of multivitamins for total parenteral nutrition--United States, 1997. JAMA 1997;278(2):109, 111.
Abbas ZG, Swai AB. Evaluation of the efficacy of thiamine and pyridoxine in the treatment of symptomatic diabetic peripheral neuropathy. East Afr Med J 1997;74(12):803-808.
Arora S, Lidor A, Abularrage CJ, et al. Thiamine (vitamin B1) improves endothelium-dependent vasodilatation in the presence of hyperglycemia. Ann Vasc Surg 2006 Sep;20(5):653-8. Epub 2006 May 31.
Avenell A, Handoll HH. Nutritional supplementation for hip fracture aftercare in older people. Cochrane Database Syst Rev 2005;(2):CD001880.
Benton D, Fordy J, Haller J. The impact of long-term vitamin supplementation on cognitive functioning. Psychopharmacology (Berl) 1995;117(3):298-305.
Cook CC, Hallwood PM, Thomson AD. B Vitamin deficiency and neuropsychiatric syndromes in alcohol misuse. Alcohol Alcohol 1998;33(4):317-336.
Hamadani M, Awan F. Role of thiamine in managing ifosfamide-induced encephalopathy. J Oncol Pharm Pract. 2006 Dec;12(4):237-9.
Nakasaki H, Ohta M, Soeda J, et al. Clinical and biochemical aspects of thiamine treatment for metabolic acidosis during total parenteral nutrition. Nutrition 1997;13(2):110-117.
Nolan KA, Black RS, Sheu KF, et al. A trial of thiamine in Alzheimer's disease. Arch Neurol 1991;48(1):81-83.
Olsen BS, Hahnemann JM, Schwartz M, et al. Thiamine-responsive megaloblastic anaemia: a cause of syndromic diabetes in childhood. Pediatr Diabetes 2007 Aug;8(4):239-41.
Ranganathan LN, Ramaratnam S. Vitamins for epilepsy. Cochrane Database Syst Rev 2005;(2):CD004304.
Saif MW. Is there a role for thiamine in the management of congestive heart failure? South Med J 2003;96(1):114-115.
Seligmann H, Halkin H, Rauchfleisch S, et al. Thiamine deficiency in patients with congestive heart failure receiving long-term furosemide therapy: a pilot study. Am J Med 1991;91(2):151-155.
Sohrabvand F, Shariat M, Haghollahi F. Vitamin B supplementation for leg cramps during pregnancy. Int J Gynaecol Obstet 2006 Oct;95(1):48-9.
Yates AA, Schlicker SA, Suitor CW. Dietary Reference Intakes: the new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98(6):699-706.

January 01, 2008.

Natural Standard Logo This evidence-based monograph was prepared by the Natural Standard Research Collaboration. The information provided should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. Talk to your health care provider before taking any prescription or over the counter drugs (including any herbal medicines or supplements) or following any treatment or regimen. Copyright© 2009 Natural Standard (www.naturalstandard.com). All Rights Reserved.