Cart

Your cart is empty

Water-soluble vitamin

Vitamin B1

thiamin

Carbohydrate energy metabolism, nerve and heart function

Essential nutrient

Reference intakes (RDA or AI) are set by the National Academies of Sciences, Engineering, and Medicine. Deficiency thresholds come from clinical and WHO guidance.

At a glance

Women, 19-50

1.1 mg

Men, 19-50

1.2 mg

Upper limit (adults)

Not established

How common is deficiency?

Uncommon in general population; COMMON in chronic alcohol use disorder, after bariatric surgery

Food sources

Animal sources

Pork (richest), fish, trout, mussels, liver, eggs

Plant sources

Whole grains, fortified cereals/bread/rice, legumes (black beans, lentils), sunflower seeds, nutritional yeast

Deficiency and testing

Signs of deficiency

Beriberi: fatigue, loss of appetite, tingling/numbness in limbs, muscle weakness, heart failure (wet beriberi); Wernicke-Korsakoff: confusion, eye movement problems, ataxia

Who is at higher risk

Alcohol use disorder, bariatric surgery, persistent vomiting (hyperemesis), diets based on polished white rice, dialysis, diuretic use

How it is tested

Erythrocyte transketolase activity coefficient (ETKAC / TPP effect); whole-blood thiamine diphosphate (HPLC); urinary thiamin

Cut-offs

ETKAC (TPP effect) >25% = deficiency; whole-blood TDP <70 nmol/L is commonly used

Symptoms are not specific. Only a clinician with the right tests can tell whether you are deficient.

Supplement forms

Common forms

thiamin HCl, thiamin mononitrate, benfotiamine (fat-soluble), thiamine pyrophosphate (TPP), injectable thiamine.

More effective

thiamin HCl/mononitrate for dietary shortfall (effective and inexpensive); benfotiamine for higher tissue levels (studied in diabetic neuropathy); IV/IM thiamine for alcohol use disorder with Wernicke symptoms or severe malabsorption (oral absorption is limited).

Less effective

oral thiamine alone in active alcohol use disorder or after bariatric surgery with vomiting (poor absorption); TPP and other 'active' forms (no proven advantage over standard oral thiamine).

Safety, interactions and halal notes

Safety and interactions

Upper limit for adults: Not established. Going above the upper limit over time can cause harm, so check labels and talk to a clinician before high-dose supplements.

Halal note

The nutrient itself is not a halal question. For supplements, check the delivery form: gelatin (pork or non-halal bovine), capsule shells, glycerin, and alcohol-based carriers need halal certification. Ask for the halal certificate, not just a label claim. This is general guidance, not a certification.

Frequently asked questions

How much Vitamin B1 do adults need per day?

Women 19-50: 1.1 mg. Men 19-50: 1.2 mg. Upper limit: Not established. Needs change with age, pregnancy and health conditions.

What are the signs of Vitamin B1 deficiency?

Beriberi: fatigue, loss of appetite, tingling/numbness in limbs, muscle weakness, heart failure (wet beriberi); Wernicke-Korsakoff: confusion, eye movement problems, ataxia. These signs are not specific, so only a clinician with the right tests can confirm a deficiency.

What are the best food sources of Vitamin B1?

Animal sources: Pork (richest), fish, trout, mussels, liver, eggs. Plant sources: Whole grains, fortified cereals/bread/rice, legumes (black beans, lentils), sunflower seeds, nutritional yeast.

Which form of Vitamin B1 supplement is best?

Sources

NIH Office of Dietary Supplements fact sheet

← Back to the full nutrient guide

This page is for education only and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to a qualified clinician before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a medical condition. Daily needs are US reference intakes for adults 19-50.

Share this page