Vital for metabolising food. Low levels of thiamin lead to tiredness and irritability.

Good food sources for thiamin are pork, cereals and milk. Those who have a high sugar and simple carbohyrate diet are often deficient. Drinking coffee, tea and alcohol also inhibit the uptake of thiamin.

The RDA of thiamin is 1mg for men and 0.8mg for women.

Supplements of thiamin can disrupt some heart medicines and diuretics.