Thiamine, or Vitamin B1, is a crucial water-soluble vitamin that helps convert food into energy, supports nerve function, muscle contraction, and cell growth, and is vital for metabolism, found in foods like grains, beans, nuts, and meat, and also available as supplements to prevent/treat deficiencies like beriberi and Wernicke-Korsakoff syndrome. Since the body stores very little thiamine, a daily intake is necessary for continuous health.