Vitamin B-1, also known as Thiamin, is a member of the B-Vitamin family that is naturally found in cereal grains, beans, nuts, eggs, and meats. Thiamin is involved in numerous body functions, including nervous system and muscle functioning, the flow of electrolytes in and out of nerve and muscle cells, carbohydrate metabolism, and the production of hydrochloric acid, which is necessary for proper digestion.