Beriberi is a condition in which an individual lacks enough thiamine in the body, according to Healthline. Its major cause is a thiamine-low diet. Other causes include alcohol, which affects the body's ability to retain thiamine; hyperthyroidism; chronic diarrhea, which hinders thiamine absorption; and diseases such as liver disease.
Beriberi is of two types: wet beriberi and dry beriberi, notes Healthline. While wet beriberi may hinder the normal functioning of the heart, dry beriberi may cause nerve damage, resulting in muscle weakness and eventual muscle paralysis. The symptoms of wet beriberi include rapid heart rate, lower-leg inflammation and shortness of breath while performing physical activities. Dry beriberi causes pain, vomiting, speech difficulty, paralysis and mental confusion.