🧬 Family & Essentiality

🌿 Plain-Language Summary

Vitamin B1 helps your body turn food into energy ⚡. It is especially important for carbohydrate metabolism and for the health of the nervous system. Without thiamine, glucose cannot be properly used by the brain and muscles.

⚗️ Molecular & Chemical IDs

• Thiamine: C₁₂H₁₇N₄OS⁺ (various salts e.g., thiamine hydrochloride)
• Coenzymes: TPP (thiamine pyrophosphate), TMP (thiamine monophosphate)
• Sensitivity: Heat, sulphite preservatives, and alkaline conditions degrade thiamine

⚡ Functions

• Coenzyme (TPP) for pyruvate dehydrogenase and α-ketoglutarate dehydrogenase — critical steps in energy production (ATP)
• Coenzyme for transketolase in the pentose phosphate pathway — generates NADPH and ribose (for nucleic acids)
• Supports nerve conduction and neuromuscular function via acetylcholine synthesis

🍽️ Absorption & Bioavailability

🇦🇺 Australian NRVs (NHMRC — RDI)

• Adult men: 1.2 mg/day
• Adult women: 1.1 mg/day
• Pregnancy: 1.4 mg/day
• Lactation: 1.4 mg/day

UL (Upper Level): Not established

🚨 Deficiency & Excess

Deficiency

• Beriberi:
  • Dry: peripheral neuropathy, weakness
  • Wet: cardiac failure, oedema
• Wernicke-Korsakoff syndrome: confusion, ataxia, memory impairment (seen in chronic alcohol misuse)
• General: fatigue, irritability, appetite loss

Excess

No known toxicity from food; high supplemental doses are generally well tolerated.

🥗 Food Sources

• Whole grains, fortified breads & cereals (mandatory thiamine fortification in Australian bread-making flour)
• Legumes, nuts, seeds
• Pork, organ meats (excellent sources)

🧪 Testing & Monitoring

• Best marker: Whole-blood or erythrocyte thiamine diphosphate (TPP)
• Functional test: Erythrocyte transketolase activity coefficient (ETKAC)
• Testing considered in alcohol misuse, diuretic use, bariatric surgery, dialysis, or unexplained neuropathy

🔗 Interactions

• Alcohol and chronic diuretics deplete thiamine
• Raw freshwater fish/shellfish contain thiaminases (destroy thiamine) — inactivated by cooking
• Sulphite preservatives in foods can degrade thiamine

📊 Evidence Snapshot

• 🔬✅ Well-established: Carbohydrate metabolism and neurological function
• 🧪⚖️ Clinical use: Treatment of deficiency in at-risk groups (alcohol misuse, bariatric surgery, chronic illness)
• ⚠️❌ Unproven/hype: Broad claims for high-dose thiamine in healthy individuals