Thiamin

Vitamin B1 — historically also called vitamin F — a water-soluble member of the B-vitamin group. Its active form, thiamin pyrophosphate, serves as a coenzyme for decarboxylation reactions in carbohydrate metabolism; the vitamin supports normal nervous-system function and the muscle tone of the gastrointestinal tract. Severe deficiency produces beriberi. Good sources include unrefined cereals, beans, pork and organ meats (liver, kidney, heart), yeasts, potatoes, peas, and nuts. Cooking destroys or leaches up to half the thiamin in foods — it is heat-labile and water-soluble — so preparation methods strongly affect how much reaches the plate, a key factor in dietary assessment.