Vitamin B1
| Vitamin B1 | |
|---|---|
 | |
| Vitamin name | Thiamine |
| Chemical formula | C₁₂H₁₇N₄OS⁺ |
| Solubility | Water-soluble |
| Discovery year | 1911 - Isolated by Casimir Funk
1936 - synthesized by Robert Williams |
| Daily requirement (RDA) | 1.1 mg for adult females and 1.2 mg for adult males |
| Upper limit | safe even at high doses, excess is excreted in urine |
| Rich food sources | pork, poultry, fish, |
Introduction
Thiamine, also known as vitamin B1, is an essential nutrient that plays a crucial role in energy metabolism[1] and overall health. It is a water-soluble vitamin that plays an important role in the conversion of carbohydrates into energy in the body. Thiamine is essential for the proper functioning of the nervous system, heart and muscles.[2][3] It is synthesized by microorganisms, fungi and plants, whereas animals and humans have to obtain it from food.
Structure/Chemical properties
The thiamine molecule is composed of pyrimidine and thiazole rings which are linked by a methylene bridge. It exists in a free form as a thiamine, or as a mono-, di- or triphosphate. Vitamin B1 stands out for its nonflammable, water-soluble, inexpensive, and non-toxic characteristics. The hydroxyl group (-OH) is the point of attachment of a phosphate group, which enables the formation of biologically active derivatives.
Function/Mechanism of Action
Thiamine was the first vitamin identified. It functions as a catalyst in the generation of energy through decarboxylation of branched-chain amino acids and alpha-ketoacids and acts as a coenzyme for transketolase reactions in the form of thiamine pyrophosphate. Thiamine also plays an unidentified role in propagating nerve impulses and taking part in myelin sheath maintenance.
The key carbohydrate metabolic pathways involve thiamine phosphate derivative - thiamine pyrophosphate (TPP) dependent enzymes. TPP is an essential cofactor for steps regulating glycolysis, the pentose phosphate cycle, and the [[Terminology#Citric acid cycle (Krebs cycle or TCA cycle]|Krebs cycle]].
Notably, thiamine is one of the two most important cofactors of pyruvate dehydrogenase (PDH) (along with magnesium). Thiamine both upregulates PDH activity and inhibits PDK (pyruvate dehydrogenase kinase), restoring glucose metabolism and raising CO2 levels[4], with broad systemic benefits. It also acts as a carbonic anhydrase inhibitor.
Medical uses/Effects
Wernicke-Korsakoff Syndrome: From the clinical point of view thiamine deficiency is related to beri-beri, cardiovascular, nervous, and immune systems, Parkinson disease, Alzheimer disease, Wernicke-Korsakoff syndrome and other pathologies of the nervous system.[1]
Alcohol-induced brain damage: Thiamine prevents iron accumulation in the brain and restores the blood-brain barrier.[2]
Heart failure: Wet beri-beri is the characteristic vitamin B1 deficiency disease, which is also characterized by heart failure. Evidence suggests that heart failure can be improved by the additional administration of Vitamin B1.
Anxiety/Lactic acid: Studies report dramatic relief from anxiety using thiamine alone or combined with carbonic anhydrase blockers, the mechanism involves lowering lactic acid and increasing CO2.
Neurological disorders: Friedreich's ataxia could be the manifestation of a thiamine deficiency because of enzymatic abnormalities. High-dose thiamine (600mg–1200mg) combined with biotin (150mg) has shown promise in Huntington's disease and MS.[5]
Side/Adverse effects
A prospective evaluation of thiamine hydrochloride given as a 100-mg IV bolus in 989 consecutive patients (1,070 doses) found a total of 12 adverse reactions (1.1%). Minor reactions consisting of transient local irritation were seen in 11 patients (1.02%), and there was only one major reaction (0.093%) consisting of generalized pruritus. Thiamine hydrochloride may be administered intravenously without undue concern..[3]
Anaphylaxis as an adverse systemic reaction to thiamine has been described since 1938. The reaction appears to involve immediate type hypersensitivity and to be exclusively related to parenteral administration. Oral thiamine is considered extremely safe with no established upper limit[6]
Dosing
| Use Case | Dose |
|---|---|
| RDA (adults) | 1.1–1.2 mg/day
|
| General supplementation | 100–300 mg/day oral
|
| Wernicke's encephalopathy (established) | 200–500 mg IV three times daily for 3–5 days, followed by 250–1000 mg/day oral
|
| High-risk deficiency | 250–500 mg/day parenteral for 3–5 days, then 250–300 mg/day oral
|
| Uncomplicated alcohol dependence | 250–500 mg/day oral for 3–5 days, then 100–250 mg/day
|
| Neurological conditions (Huntington's, ataxias) | 600–1200 mg/day (often combined with biotin)
|
