Beriberi is an ailment caused by a thiamine deficiency. It is a disease that affects the nervous system and can lead to paralysis, heart failure, and even death. Symptoms include fatigue, loss of appetite, weight loss, and tingling in the extremities. It is most common in areas where polished white rice is a dietary staple, as thiamine is lost during the polishing process. Treatment includes thiamine supplementation and a diet rich in whole grains.