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Thiamine (vitamin B1)

Published on April 30, 2026   7 min

A selection of talks on Cardiovascular & Metabolic

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0:00
Hello. My name's Susan Fairweather-Tait. I'm a professor of human nutrition in the Norwich Medical School at the University of East Anglia in the UK. I'm going to be talking to you about thiamine, spelled with or without an E, which is also known as vitamin B1.
0:17
Free thiamine functions as the precursor for thiamine diphosphate, TDP, which is also called thiamine pyrophosphate, TPP. This acts as a coenzyme for enzymes involved in carbohydrate and branched-chain amino acid metabolism and in energy-yielding reactions. TDP is required for the function of the brain and the nervous system.
0:41
Thiamine is present in all plant food sources as free thiamine, and it's present in animal tissues in phosphorylated forms. The main food sources include whole grains, pulses, potatoes, meat (especially pork), liver, and fish. As a water-soluble vitamin, thiamine is readily lost through leaching into cooking water. It's unstable to light, so some is lost when foods, such as baked goods, are exposed to sunlight. There are also losses with food processing. So alkaline pH, high temperatures, exposure to sulphites, all contribute to significant thiamine loss. For example, in potato products that have been blanched by immersion in sulphite solution. Polyphenols, such as tannic acid in tea, will destroy thiamine.
1:30
Thiamine phosphate esters are hydrolyzed to thiamine (T) in the intestinal lumen by intestinal phosphatases in the brush-border membrane. Thiamine is absorbed by active transport in the duodenum and the proximal jejunum, and by carrier-mediated transport in the colon. Thiamine is carried across the mucosal membrane by transporters, and either converted to TPP or transported into the blood. In healthy subjects, thiamine absorption is >95% at intakes <2mg, and daily intakes in adults are 1-2mg/d. Much of the absorbed thiamine is phosphorylated in the liver,

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