WHAT DOES VITAMIN B1 DO?
It contributes to normal energy yielding, and carbohydrate metabolism. Thiamine pyrophosphate is required as a coenzyme for a few but important enzymes that enable pyruvate to form Acetyl Co A and alpha ketoglutarate to form Succinyl-Co A products in the cells that make energy from food. http://pubs.niaaa.nih.gov/publications/arh27-2/134-142.htm
It contributes to normal functioning of the nervous system. In the brain Thiamine is required by nerve cells and supporting nervous system cells (or "glial cells"), it's also needed to create neurotransmitters.
It contributes to normal psychological function – Thiamine Pyrophosphate is necessary to create some neurotransmitters (brain chemicals) that are essential for normal psychological function.
It contributes to the normal function of the heart -Thiamine is found in high concentration in the heart as well as the brain, liver and kidney. The heart is particularly sensitive to Thiamine deficiency, and impairment of the Thiamine Pyrophosphate dependent enzymes primarily affects the heart and nervous system.