Table of ContentsView AllTable of ContentsWhat Is Thiamine?UsesDeficiencyDosageToxicitySide EffectsInteractionsSourcesSimilar Supplements
Table of ContentsView All
View All
Table of Contents
What Is Thiamine?
Uses
Deficiency
Dosage
Toxicity
Side Effects
Interactions
Sources
Similar Supplements
Thiamine(vitamin B1) is a water-soluble vitamin that helps the growth and function of your body’s cells.It’s needed for a healthy liver, skin, eyes, hair, and brain. It’s also thought to help strengthen your immune system.Some studies are looking at thiamine’s benefits for Alzheimer’s disease, cataracts, diabetes, and heart failure. However, more research is needed to confirm its effects.
If you have a thiamine deficiency, it can cause symptoms like weight loss, confusion, and muscle weakness. A severe deficiency, beriberi, may result in peripheral neuropathy (nerve damage) and congestive heart failure.Drinking too much alcohol can causeWernicke-Korsakoffsyndrome, a thiamin deficiency that needs immediate treatment to prevent permanent harm to the brain, heart, and nerves.
In the United States, the Food and Drug Administration (FDA) does not regulate supplements the way it regulates prescription drugs. That means some supplement products may not contain what the label says. Whenchoosing a supplement, look for independently tested products and consult a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.
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Thiamine is a water-soluble vitamin that is found in some foods and may also be taken as a supplement. The body’s cells need thiamine to generate energy, develop, grow, and function.
Thiamine helps some of the enzymes in the body that are used in metabolizingglucose(sugar), which in turn provides cells with energy. This makes thiamine levels important in diseases of the metabolic and gastrointestinal systems.
A deficiency of thiamine, or vitamin B1, may go undiagnosed and is associated with poor health outcomes.A severe deficiency could lead to decreased production of some enzymes and go on to cause problems in brain function and even death.
Thiamine Supplement Benefits
The following conditions include studied uses of thiamine:
What Causes Thiamine Deficiency?
Thiamine is absorbed in the small intestine. For healthy adults in the United States, a balanced diet usually provides enough thiamine.Thiamine is stored in the liver, but only in small amounts, so people need a steady supply from their diet or a supplement to avoid a deficiency.
Thiamine deficiency may occur when people either do not get enough thiamine from their diet or do not absorb it properly. The incidence of a thiamine deficiency is higher in some groups of people, including:
Bariatric surgery rates have increased dramatically from 2006 through 2021.A 2024 systematic review and meta-analysis noted an increase in thiamine deficiency in the first few months and up to a year following bariatric surgery.
The study authors also noted that pregnant people with a prior history of bariatric surgery are particularly at risk for thiamine deficiency with the greatest risk in the first trimester (12%) but continued risk in the second (8%) and third (10%) trimesters.
A healthcare provider may recommend checking thiamine levels as part of an overall management plan, especially before and after bariatric surgery. This may help catch a deficiency early, bring levels up to normal, and avoid complications.
If any thiamine deficiency symptoms appear, talk to a healthcare provider right away.
How Do I Know if I Have a Thiamine Deficiency?
When thiamine levels get too low, it may initially cause signs and symptoms such as the following:
A more severe or long-term thiamine deficiency may causeberiberiand Wernicke-Korsakoff syndrome.
Who Is at Higher Risk of Thiamine Deficiency?
Thiamine deficiencies are more common in areas with less access to food sources of thiamine.
Factors that can increase the risk of thiamine deficiency include:
How Are Thiamine Levels Tested?The level of the active form of thiamine (thiamine diphosphate) in whole blood is tested to determine a deficiency.Urine tests, which measure how much thiamine is being excreted, might also be used. If low levels of thiamine are found in the urine, it might mean not enough thiamine is in the diet.
How Are Thiamine Levels Tested?
The level of the active form of thiamine (thiamine diphosphate) in whole blood is tested to determine a deficiency.Urine tests, which measure how much thiamine is being excreted, might also be used. If low levels of thiamine are found in the urine, it might mean not enough thiamine is in the diet.
Dosage: How Much Thiamine Should I Take?
Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.
Note that Verywell Health prefers to use inclusive terminology, but when citing health authorities or studies, the terms relating to sex and gender from those sources are used.
What Happens if I Take Too Much Thiamine?
There’s no upper limit set on thiamine supplements.Taken orally, it’s not expected to cause adverse reactions at higher levels, but there’s also no data to prove otherwise. However, as with any supplement, it’s still important to check with a healthcare provider on an appropriate dosage.
What Are the Side Effects of Thiamine?
Thiamine doesn’t stay in the body for long, which is one reason deficiencies occur.It’s not thought that supplementing with thiamine causes any adverse side effects.
When thiamine is given through an IV for serious deficiencies, there may be a risk of an allergic reaction, but the benefits would outweigh the risks in these cases. Giving the supplement slowly and with fluids may help cut this risk, but there aren’t any accepted guidelines.
Oral thiamine isn’t expected to interact with most medications.
There is also some evidence that the medicationsLasix (furosemide)and Adrucil (fluorouracil) could cause the body to lose too much thiamine.Your healthcare provider may suggest a supplement if you take these medications.
It is essential to read a supplement’s ingredient list and nutrition facts panel carefully to determine which ingredients and how much of each ingredient are included. Review this supplement label with your healthcare provider to discuss any potential interactions with foods, other supplements, and medications.
Sources of Thiamine and What to Look For
Most people get enough thiamine in their food. It is naturally present in whole grains, meat (especially pork), and fish.Some foods (bread, cereals, and infant formula) are fortified with thiamine to ensure most people receive enough in their diet.
Food Sources of Thiamine
There are many whole-food and fortified-food sources of thiamine, including:
Thiamine Supplements
Thiamine (vitamin B1) is often found in multivitamins, usually with other B vitamins. It can also be taken as a supplement on its own, in capsule or liquid form.
Often, supplements that can be bought over the counter contain thiamine mononitrate or thiamine hydrochloride, which are stable forms of thiamine.Some available supplements may include one or more synthetic forms of vitamin B1.
Thiamine will be given in the hospital through an IV for severe deficiencies.
Thiamine is vitamin B1, of which there are several different types that are used as supplements. Some occur naturally in foods but might also be made synthetically in a lab.
Some other forms of thiamine or vitamin B1, or derivatives, include:
Summary
Thiamine is a water-soluble vitamin that is important to essential functions in the body. It is not stored in the body, so a steady supply is needed. Most people get enough thiamine through their diet. However, certain groups of people may be at risk of deficiency, either because they can’t get enough thiamine in their diet or their bodies can’t absorb it properly.
A thiamine deficiency can become serious, so it’s important for those who might lack thiamine to be tested and receive a supplement.
36 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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