Skip to content

Coming soon. The store is not open yet.

Menu
Full Measure

Ingredient guide

How much thiamine per day?

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

Men need 1.2 mg of thiamine a day and women 1.1 mg, rising to 1.4 mg during pregnancy and breastfeeding. Most people get this from food. No upper limit has been set, and above about 5 mg a day the gut absorbs a smaller share of each extra milligram.1,2,3

Key facts

  • Children need 0.5 to 0.9 mg a day, depending on age.1
  • European reference values work by energy: 0.4 mg for every 1,000 kcal an adult eats.3
  • In a study of six adults, only about 5% of a 50 mg dose by mouth reached the blood.4
  • A typical multivitamin carries about 1.5 mg of thiamin.2

Recommended amounts by age and stage

Thiamin recommended daily amounts (RDA)1,2
Age or stageAmount per day
Babies 0 to 6 months0.2 mg (adequate intake)
Babies 7 to 12 months0.3 mg (adequate intake)
Children 1 to 30.5 mg
Children 4 to 80.6 mg
Children 9 to 130.9 mg
Teen boys 14 to 181.2 mg
Teen girls 14 to 181.0 mg
Men1.2 mg
Women1.1 mg
Pregnancy1.4 mg
Breastfeeding1.4 mg

These are Recommended Dietary Allowances: amounts that cover the needs of nearly all healthy people, 97% to 98%, in each group. They count thiamin from every source, food and supplements together.2

The Daily Value used on food and supplement labels is 1.2 mg of thiamin for adults and children aged 4 and older.2

How much people actually get

Adults in the United States average 1.95 mg of thiamin a day from food for men and 1.39 mg for women. Counting supplements, both average about 4.9 mg.2

Most people in the United States get enough thiamin: in national survey data, about 6% had usual intakes below the average requirement.2

Put simply, the typical adult already eats more thiamin than the RDA, and once supplements are counted, the average across all adults is about four times it.2

The European approach: by energy intake

European reference values tie thiamin to energy intake: 0.4 mg per 1,000 kcal for all adults, including during pregnancy and breastfeeding.3

On that basis, someone eating 2,000 kcal a day needs about 0.8 mg and someone eating 3,000 kcal about 1.2 mg. EFSA chose this method because depletion and refilling studies showed that people who use more energy need more thiamin, and there was no evidence of a difference between men and women, or younger and older adults, once energy was taken into account.3

The body's need for thiamin rises when a diet is higher in carbohydrate.3,5

Why bigger doses add less

At usual intakes the gut absorbs more than 95% of thiamin, through a carrier that fills up. Above about 5 mg a day, a smaller share is absorbed.2,3

Only about 5% of a 50 mg dose taken by mouth reached the blood, compared with the same dose given into a vein.4

At high doses, thiamin also crosses the gut wall passively, so blood levels keep climbing with the dose: peak levels after 1,500 mg were about ten times those after 100 mg.2,6

So a large tablet is not wasted entirely, but most of it does not stay in the body. What is absorbed beyond the body's needs is passed in urine.2

What's in ours

What’s in ours

  • Men's Multi: Vitamin B1, 7 mg per serving, from the label

When the amount is a medical question

Some people need more than food provides, and the right amount is a doctor's call. That includes people with alcohol dependence, people who have had bariatric surgery and people taking furosemide. In heavy drinkers, guidelines cited by NIH use far higher doses than the RDA, and injections for those at high risk.2

  • Ask your doctor before high doses if you are pregnant, especially with frequent vomiting
  • Ask your pharmacist if you take furosemide or fluorouracil, which can lower thiamin1
  • Do not take thiamin if you have had an allergic reaction to it5

Questions people ask

Is 100 mg of thiamine a day too much?

No upper limit has been set, and NIH reports no harm from intakes of 50 mg a day or more. Even so, 100 mg is far more than a healthy person needs, and most of it is either not absorbed or passed in urine. Ask a doctor why you would need that much.2,4

Do women need less thiamine than men?

Slightly. The US amount is 1.1 mg for women and 1.2 mg for men, and it rises to 1.4 mg in pregnancy and while breastfeeding. European values make no distinction between the sexes, because they scale with energy intake.1,3

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure lineMen's Multi

Sources

  1. Office of Dietary Supplements, National Institutes of Health. Thiamin: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-07.
  2. National Institutes of Health, Office of Dietary Supplements. Thiamin: Fact Sheet for Health Professionals. Updated February 9, 2023. Opened 2026-10-07.
  3. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Dietary reference values for thiamin. EFSA J. 2016;14(12):e04653. Opened 2026-10-07.
  4. Tallaksen CM, Sande A, Bohmer T, Bell H, Karlsen J. Kinetics of thiamin and thiamin phosphate esters in human blood, plasma and urine after 50 mg intravenously or orally. Eur J Clin Pharmacol. 1993;44(1):73-78. Opened 2026-10-07.
  5. Thiamine hydrochloride injection: prescribing information (Lifestar Pharma). DailyMed, U.S. National Library of Medicine. Published October 1, 2026. Opened 2026-10-07.
  6. Smithline HA, Donnino M, Greenblatt DJ. Pharmacokinetics of high-dose oral thiamine hydrochloride in healthy subjects. BMC Clin Pharmacol. 2012;12:4. Opened 2026-10-07.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.