Beriberi is a disease caused by a deficiency of thiamine, also known as vitamin B1. It is characterized by a wide range of symptoms, including fatigue, muscle weakness, and nerve damage. The name of the disease is derived from a Sinhalese word meaning 'I cannot, I cannot'. Beriberi is most commonly found in areas where white rice is a staple food, as it is often milled to remove the husk, which contains most of the thiamine.