Better known examples of early descriptions of "foot qi" are by Chao Yuanfang (who lived during 550–630) in his book Zhu bing yuan hou lun (Sources and Symptoms of All Diseases) and by Sun Simiao (581–682) in his book Bei ji qian jin yao fang (Essential Emergency Formulas Worth a Thousand in Gold).In the late 19th century, beriberi was studied by Takaki Kanehiro, a British-trained Japanese medical doctor of the Imperial Japanese Navy. Beriberi was a serious problem in the Japanese navy; sailors fell ill an average of four times a year in the period 1878 to 1881, and 35% were cases of beriberi. In 1883, Takaki learned of a very high incidence of beriberi among cadets on a training mission from Japan to Hawaii, via New Zealand and South America. The voyage lasted more than nine months and resulted in 169 cases of sickness and 25 deaths on a ship of 376 men. With the support of the Japanese Navy, he conducted an experiment in which another ship was deployed on the same route, except that its crew was fed a diet of meat, fish, barley, rice, and beans. At the end of the voyage, this crew had only 14 cases of beriberi and no deaths. This convinced Takaki and the Japanese Navy that diet was the cause.
Ethanol per se inhibits thiamine transport in the gastrointestinal system and blocks phosphorylation of thiamine to its cofactor form (ThDP).Following improved nutrition and the removal of alcohol consumption, some impairments linked with thiamine deficiency are reversed, in particular poor brain functionality, although in more severe cases, Wernicke–Korsakoff syndrome leaves permanent damage. (See delirium tremens.) Wet beriberi
Wet beriberi affects the heart and circulatory system. It is sometimes fatal, as it causes a combination of heart failure and weakening of the capillary walls, which causes the peripheral tissues to become edematous. Wet beriberi is characterized by:

Increased heart rate
Vasodilation leading to decreased systemic vascular resistance, and high-output heart failure
Elevated jugular venous pressure
Dyspnea (shortness of breath) on exertion
Paroxysmal nocturnal dyspnea
Peripheral edema (swelling of lower legs) or generalized edema (swelling throughout the body)
Dilated cardiomyopathy

Gastrointestinal beriberi
Gastrointestinal beriberi causes abdominal pain. It is characterized by:

Abdominal pain
Nausea
Vomiting
Lactic acidosis

Infants
Infantile beriberi usually occurs between two and six months of age in children whose mothers have inadequate thiamine intake. It may present as either wet or dry beriberi.In the acute form, the baby develops dyspnea and cyanosis and soon dies of heart failure.