Part 1 Water Soluble Vitamins
1
74
General Information
Chemistry
Thiamin (vitamin B1) is a relatively heat- and acid-stable, water-soluble compound, containing a
pyrimidine and a thiazole nucleus linked by a methylene bridge. Derivatives of thiamin include the
mono-, pyro- and triphosphate forms and the synthetic hydrochloride and slightly less water-soluble
mononitrate salt. Synthetic non water-soluble derivatives of thiamin are available but these are not used
in food supplements.
Occurrence in food, food supplements and medicines
Foods providing rich sources of thiamin include unrefined grain products, meat products, vegetables,
dairy products, legumes, fruits and eggs. In the UK there is mandatory fortification of white and brown
flour with thiamin, to a level of not less than 0.24 mg/100g flour, to replace losses during production;
thus, cereal products are also a rich source of thiamin.
Mononitrate or hydrochloride derivatives of thiamin are present in multi-constituent medicinal products
for the prevention (dose 1 – 5 mg daily) or treatment (dose 10 – 35 mg daily) of nutrient deficiencies.
Supplements containing thiamin alone are also available (daily doses up to 300 mg).
Recommended amounts
Body stores of thiamin are limited and a regular intake is necessary. Thiamin requirement is related to
energy consumption. The RNI for adults and children 1 year is 0.4 mg/1000 kcal and 0.3 mg/1000
kcal in infants (COMA, 1991). Assuming food intakes of 2000 kcal/day and 20% losses through cooking,
this can be estimated to be 1.4 and 1 mg/day for adult males and females respectively. In pregnancy and
lactation, thiamin requirement increases to approximately 1.6 – 1.8 mg/day.
Analysis of tissue levels and thiamin status
Thiamin status may be assessed by measurement of thiamin levels in blood or by urinary excretion,
before and after loading. Erythrocyte transketolase (ETK) activity or its activation coefficient (ATK-AC) in
haemolysed red blood cells is a functional measure of thiamin status.
Brief overview of non-nutr