Vitamin B1 (thiamine) is a water-soluble vitamin vital for energy metabolism and nervous system function, converting glucose into energy and maintaining nerve health. Deficiency causes beriberi, including dry (peripheral neuropathy) and wet (cardiac issues like edema) forms, and may occur in alcoholics, those on poor diets, or with absorption problems. Preventive doses are ~1.1-1.2 mg/day for adults, while therapeutic use ranges from 5-10 mg orally thrice daily to injections for severe cases. Safe overall, injections may rarely cause allergies. Prioritize whole grains and pork in diets; avoid alkaline drugs and monitor diuretic use. Supplementation aids high-risk groups, with medical guidance advised for injections.