USANA Nutritionals

Vitamin-B1, also called thiamin or thiamine, is a water-soluble vitamin required for normal energy metabolism and cell division. Like all true vitamins, thiamin is a coenzyme, meaning that it works in tandem with one or more enzymes to catalyze metabolic reactions. Vitamin B1 (in its thiamin pyrophosphate form) is a coenzyme for four enzymes involved in carbohydrate and lipid metabolism. As such, it plays a central role in the production of energy from sugars, starch, and other fuels. Thiamin is also involved in the production of five-carbon sugars required for synthesis of DNA and RNA, and plays a role in fatty acid synthesis.
Thiamin deficiencies can be caused by chronic alcoholism and limited diets, particularly those that depend on polished rice as a staple food. Recent research indicates that thiamin deficiency is also prominent in pregnancy, warranting increased thiamin supplementation for women who are or are expecting to become pregnant.

Grain products are the most important dietary sources of thiamin. Meat products, especially pork, can also contribute significant dietary thiamin.

In humans, even very high oral doses of thiamin have been found to have no toxic effects, except for possible gastric upset.