Thiamine

Thiamine (Vitamin B1) is a B complex vitamin important in the metabolism of energy from carbohydrates, the production of RNA and DNA, and nerve function.

Thiamine pyrophosphate (TPP) is part of the conversion of acetyl coenzyme A (CoA).

Chronic fatigue syndrome
One very small study found decreased functional status of several B vitamins including pyroxidine, riboflavin and thiamine.