Vitamin B1 (Thiamin)

Your intake

What each level of vitamin b1 (thiamin) does

Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.

1. Severely lowYOU ARE HERE

   0 mg – 0.4 mg

   Well below target. Risk of deficiency symptoms tied to energy metabolism.

2. Insufficient

   0.4 mg – 1.2 mg

   Below the recommended daily target. Long-term adequacy not assured.

3. Adequate

   1.2 mg – 1.8 mg

   Daily target met. Standard nutritional support for energy metabolism.

4. Therapeutic

   1.8 mg – 2.4 mg

   Common for specific health goals. Check the evidence for your situation before sustaining this level.

5. Diminishing returns

   2.4 mg – +

   Past the point where extra intake typically helps. Evidence for further benefit is thin.

Overview

Water-soluble B vitamin essential for carbohydrate metabolism, nerve conduction, and ATP production. Body stores are small (~30 mg) and turn over in 9–18 days, so daily intake matters. Refined-grain diets without fortification or chronic alcohol use are the most common deficiency drivers.

Functions

• ●Cofactor for pyruvate dehydrogenase (carbohydrate → acetyl-CoA)
• ●Cofactor for alpha-ketoglutarate dehydrogenase (TCA cycle)
• ●Cofactor for transketolase (pentose phosphate pathway)
• ●Required for branched-chain amino acid metabolism

Mechanism

Thiamine pyrophosphate (TPP, the active form) carries 2-carbon units in oxidative decarboxylation reactions. When thiamine is low, pyruvate cannot enter the TCA cycle, lactate accumulates, and high-glucose tissues (brain, heart) fail first. This is why thiamine deficiency presents as cardiac (wet beriberi) or neurological (dry beriberi, Wernicke).

Benefits

• ●Treatment of beriberi and Wernicke-Korsakoff syndrome (IV thiamine in acute settings)
• ●Possible reduction in diabetic neuropathy with benfotiamine (lipid-soluble derivative)
• ●Routine supplementation does not improve mood or energy in non-deficient adults

Deficiency

Rare in fortified-grain populations; common in chronic alcoholism, bariatric surgery patients, severe malnutrition, and refined-rice-dependent populations.

Excess

No established UL; water-soluble and excreted readily. Doses up to several hundred mg/day are tolerated.

Forms

• Thiamine HCl / thiamine mononitrate
  Standard supplement and food-fortification forms
• Benfotiamine
  Fat-soluble; ~5× tissue bioavailability; used for diabetic neuropathy
• Sulbutiamine
  Crosses blood-brain barrier; off-label for fatigue/mood; limited data
• Thiamine pyrophosphate (TPP)
  Active cofactor form; rarely used as supplement

Food sources

• Pork loin (cooked) · 3 oz0.7 mg
• Trout (cooked) · 3 oz0.4 mg
• Black beans (cooked) · 1/2 cup0.4 mg
• Sunflower seeds · 1 oz0.4 mg
• Fortified breakfast cereal · 1 cup0.4–1.5 mg
• Brown rice (cooked) · 1 cup0.2 mg

Supplement forms

Standard thiamin HCl is fine for most. Benfotiamine, a fat-soluble derivative, achieves higher tissue concentrations and is sometimes used for diabetic neuropathy. IV thiamine 100–500 mg is the emergency treatment for suspected Wernicke encephalopathy.

Bioavailability

Absorbed in proximal small intestine via active transport (low dose) and passive diffusion (high dose). Alcohol blocks both. Raw fish and ferns contain thiaminase that destroys dietary thiamine. Tea and coffee polyphenols modestly reduce absorption.

Longevity relevance

Adequacy matters; supplementation above adequacy does not extend lifespan or healthspan in non-deficient adults. Routine fortification of grains has largely eliminated population-level deficiency in the developed world.

Relationships

References

• NIH ODS — Thiaminguideline
• Linus Pauling Institute — Thiaminreview
• Cochrane — thiamine for Wernicke (2013)review

About Vitamin B1 (Thiamin)

Carbohydrate metabolism and nerve signaling.

Role

Energy metabolism

Daily target

1.2 mg (DV)

Also called

thiamin, thiamine, vitamin b1, vitamin b-1, thiamin hcl, thiamine hydrochloride