Vitamin B1 (Thiamine)

What it is

Thiamine (vitamin B1) is a water-soluble B-complex vitamin composed of a substituted thiazole ring linked to a pyrimidine ring. In dietary supplements, it is formulated as thiamine hydrochloride or thiamine mononitrate for enhanced shelf stability. Thiamine is phosphorylated inside human cells to form thiamine pyrophosphate (TPP or ThDP), an essential coenzyme for pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase in aerobic energy metabolism.

Also known as: Thiamine HCl, Thiamine Mononitrate, Vitamin B1

What it does

• Serves as the TPP coenzyme required for carbohydrate conversion into ATP energy.
• Supports central and peripheral nervous system function and nerve impulse conduction.
• Promotes healthy cardiovascular and myocardial muscle performance.
• Maintains gastrointestinal muscular tone and digestive enzyme secretion.

Amplified by probiotics

Dietary thiamine is absorbed in the duodenum via carrier-mediated thiamine transporters (THTR-1 and THTR-2). In the distal intestine, commensal probiotic bacteria—including Bacteroides species and select Lactobacilli—synthesize thiamine de novo. Microencapsulated probiotic delivery expands colonic thiamine pools, where local enterocytes take up free bacterial thiamine via colonic THTR transporters. In turn, thiamine pyrophosphate (TPP) fuels enterocyte Krebs cycle respiration, maintaining mucosal tissue turnover and tight junction integrity. Furthermore, probiotic short-chain fatty acids lower luminal pH, optimizing thiamine transporter affinity, enhancing enterocyte ATP generation, and preventing localized mucosal energy starvation.

Typical dose

1.1–10 mg/day

The evidence

Clinical and nutritional trials demonstrate that thiamine is essential for human oxidative carbohydrate metabolism, nerve signal transmission, and cardiovascular health. Deficiency state studies establish TPP's non-redundant role in mitochondrial pyruvate cleavage (Lonsdale 2006, Evid Based Complement Alternat Med; Frank 2015, Nutrients).

1. Lonsdale D. A review of the biochemistry, metabolism and clinical benefits of thiamin(e) and its derivatives. Evid Based Complement Alternat Med. 2006;3(1):49-59. PubMed ↗
2. Frank LL. Thiamin in human nutrition: cellular mechanisms and clinical implications. Nutrients. 2015;7(3):1618-1637. PubMed ↗

Safety & who should check first

Exceedingly high safety profile with no established upper limit (UL); rapid renal excretion prevents accumulation. Safe during pregnancy and lactation at standard supplemental levels.