Vitamin B1 (Thiamin or Thiamine)

Description Thiamin is water soluble and part of the B-vitamins group.
Function/ Used for Thiamin aids the nervous system and is essential for the functioning of some important enzymes. These enzymes have vital roles in the processes that make energy available in the body. Thiamin is essential for the transmission of certain types of nerve signal between the brain and the spinal cord.

Thiamin is also important for good brain and heart function.

Intake Recommended intake

EU NRV: 1.1mg


Thiamin requirements depend on energy intake; values are therefore often given as mg/1000 kcal and also as total values based on estimated average energy requirements for the majority of people in the UK.


UK average daily intake

Requirements vary depending on age and gender. The UK National Diet and Nutrition Survey lists up-to-date intake requirements and average intakes1.

As a supplement Not generally available as a single supplement. Commonly available as part of a multivitamin and mineral formula.

Different multivitamin and minerals products will vary in the percentage NRVs they include. People should always check the label for information about a specific product.

Found in (dietary sources) Brown rice, peas, beans and other vegetables, fortified breakfast cereals, wholemeal breads and cereals, eggs, pork, bacon and liver.
Deficiency Thiamine deficiency may lead to beri-beri (rare in the UK) which affects the cardiovascular and nervous systems. Deficiency is associated with abnormalities of carbohydrate metabolism.

Early signs of deficiency include depression, poor memory, muscle weakness and stiffness, nerve tingling, burning sensation and numbness, tiredness, headache, loss of appetite and nausea.3

Precautions and contraindications Known hypersensitivity to thiamin. Safe Upper Level: 100mg/day2
Use in pregnancy and breastfeeding There is no evidence of adverse effects in pregnancy.
Interactions e.g. with other medications Excessive alcohol intake induces thiamin deficiency.

Prolonged use of oral contraceptives may induce thiamin deficiency.

Adequate amounts of all B vitamins are required for optimal functioning; deficiency or excess of one B vitamin may lead to abnormalities in the metabolism of another.3

Adverse effects There appear to be no toxic effects (except possibly gastric upset) with high oral doses. There have, however, been rare reports of anaphylactic reactions (coughing, difficulty in breathing and swallowing, flushing, skin rash, swelling of face, lips and eyelids).
References 1.

2.     Expert Group on Vitamins and Minerals, 2003.

3.     Mason, P. Dietary Supplements. Pharmaceutical Press, London, 2001.