Vitamin B1 (thiamine mononitrate)

vitaminvitamin B1

What is it

Thiamine mononitrate is a stable salt form of vitamin B1 (thiamine) commonly used to fortify foods and as a supplement. Like other thiamine forms, it is essential for carbohydrate metabolism, nerve function, and muscle and heart health.

How it works

Thiamine mononitrate is converted to free thiamine in the digestive tract and absorbed in the small intestine. Once absorbed, it is converted to the active coenzyme form thiamine diphosphate (TDP), which serves as a cofactor for several enzymes critical for carbohydrate metabolism: pyruvate dehydrogenase (converting pyruvate to acetyl-CoA), alpha-ketoglutarate dehydrogenase (in the citric acid cycle), and transketolase (in the pentose phosphate pathway). Thiamine mononitrate is preferred for food fortification and many supplements because it is more chemically stable than thiamine HCl, particularly during food processing, baking, and storage. Bioavailability of mononitrate is similar to HCl. The brain, heart, and skeletal muscle have particularly high thiamine demands due to their dependence on carbohydrate metabolism for energy. Thiamine deficiency, whether from dietary inadequacy, alcohol use, or absorption issues, can rapidly cause symptoms in these tissues. Body stores are small (only several weeks of reserves), so regular intake matters.

Evidence for 4 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Beriberi prevention

Grade A

Strong evidence

Thiamine mononitrate effectively prevents and treats beriberi. Food fortification with thiamine mononitrate has substantially reduced beriberi worldwide.

Maintenance of normal energy metabolism

Grade A

Strong evidence

Thiamine is essential for normal carbohydrate metabolism and ATP production. Deficiency impairs energy metabolism in many tissues.

Nervous system function

Grade A

Strong evidence

Thiamine is required for normal nerve function. Deficiency causes peripheral neuropathy and central nervous system symptoms.

Cardiovascular function (in deficiency)

Grade B

Good evidence

Severe thiamine deficiency causes wet beriberi with heart failure, which responds to thiamine. Effects in adequately replete adults are not significant.

3 commercial forms

Thiamine mononitrate

Stable form preferred for food fortification and supplement formulation.

Commonly used in cereal fortification, multivitamins, and B-complex supplements.

Thiamine HCl

Similar bioavailability; less stable in processed foods.

More common in standalone thiamine supplements.

Benfotiamine

Lipid-soluble derivative; better tissue penetration.

Used in research and clinical applications for higher tissue thiamine.

Dosage

The RDA for thiamine is 1.2 mg/day for men and 1.1 mg/day for women. Most fortified foods and basic supplements provide 1.5 to 50 mg per serving. No Tolerable Upper Intake Level has been established due to low toxicity.

When and how to take it

WHEN: Take at any time of day. With or without food are both acceptable. HOW: Take with water. Often included in multivitamins and B-complex supplements. For fortification purposes, the mononitrate form is preferred for its stability.

Food sources

Food	Amount	%DV
Fortified breakfast cereals	1 serving	100%
Pork (lean)	3 oz	56%
Black beans	1/2 cup cooked	35%
Brown rice	1 cup cooked	15%
Sunflower seeds	1 oz	35%
Tuna	3 oz	19%

Safety

Thiamine mononitrate has an excellent safety record. Side effects from oral supplementation are very rare. No Tolerable Upper Intake Level is established.

Who should be cautious

Pregnant and breastfeeding women have increased thiamine needs. People with chronic alcohol use disorder, malabsorption disorders, long-term diuretic use, or bariatric surgery should ensure adequate intake. Most healthy adults consuming varied diets do not need additional supplementation.

Interactions

Loop diuretics (especially furosemide) increase thiamine excretion. Alcohol significantly impairs absorption. Some chemotherapy agents may interact with thiamine metabolism. Antacids may modestly reduce absorption.

Frequently asked questions

Why is thiamine mononitrate used in fortification?⌄

Thiamine mononitrate is more chemically stable than thiamine HCl, particularly during food processing, baking, and prolonged storage. This makes it the preferred form for fortifying flour, cereals, and other processed foods.

Is it as effective as other thiamine forms?⌄

Yes. Bioavailability is similar to thiamine HCl. The active coenzyme in the body is the same regardless of the supplement form. Benfotiamine is the exception, offering higher tissue penetration.

Do I need to take a thiamine supplement?⌄

Most adults consuming varied diets with fortified grains and varied protein sources easily meet thiamine needs. Supplementation matters for those at risk (alcohol use, malabsorption, diuretics, certain medical conditions).

Is thiamine mononitrate safe?⌄

Yes. It has an excellent safety profile with no established Upper Intake Level. Even high doses are well tolerated.

How does it differ from benfotiamine?⌄

Benfotiamine is a lipid-soluble derivative with significantly higher bioavailability and tissue penetration. It is preferred for specific applications like diabetic neuropathy where higher tissue thiamine is desired.

References

NIH Office of Dietary Supplements - Thiamin — ODS link

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.