Thiamin is the first in line of the B group vitamins, each of which functions in many different ways to help enzymes carry out many thousands of complex functions in the body. This is why they are also called coenzymes. The most important thing to remember about the B vitamins is that they work together. Large doses of any one may be of little or no health value - and may simply upset the balance of the other B vitamins.

Functions:

Thiamin is essential for the body to be able to use carbohydrates to release energy. It is essential for the brain, nervous system, digestive system and the heart.

Deficiencies:

Without thiamin, the body cannot use carbohydrates to produce energy. Muscle weakness, poor appetite, tiredness, loss of memory and irritability can result. Worst case scenario deficiencies lead to beri beri (mainly found in third world countries) and a disease called Wernicke-Korsakoff syndrome which occurs amongst people who consume excess alcohol.

Sources:

Bread and cereals often have thiamin added back in, especially wholegrain products, yeast-extract products such as Vegemite, meat (especially liver, kidneys, and lean pork) and vegetables such as white sweet potato, peas and asparagus. Also found in milk and milk products and in some fruits such as banana.

RDI:

Adults: 0.7 - 1.1 mg/day.
Children aged 8-11 yrs: 0.8 - 0.9 mg/day.
Children aged 12-15 yrs: 1 - 1.2 mg/day.
Children and teenagers 16 - 18 yrs: 0.9 - 1.2 mg/day.

Source: Growcom's formulaforlife - choose good health & happiness.