Explain the Effect of Deficiency of Thiamin?

Thiamin deficiency causes the disease beriberi in human beings, which has been classically considered to exist in dry (paralytic) and wet (oedematous) forms. The early clinical features are anorexia and dyspepsia, associated with heaviness and weakness of the legs. There is tenderness of the calf muscles on pressure with complaints of 'pins and needles' pain and numbness in the legs. The knee jerks are usually sluggish but occasionally slightly exaggerated. The subject feels weak and get easily exhausted while working. If not treated, the subjects may develop polyneuritic beriberi, that is, inflammation of many or all of the peripheral nerves.