Numbness and a burning sensation in the ankle and foot is a neuropsychiatric symptom in patients with beriberi. Thiamine is a precursor of thiamine pyrophosphate (TPP), an important coenzyme in the decarboxylation of pyruvate and alpha-ketoglutarate in the tricarboxylic acid cycle and a coenzyme of erythrocyte ketolyltransferase. In addition, it is also related to brain cell activity and nerve impulse transmission. Once deficient, can cause a series of neurological and circulatory symptoms, called beriberi (foot disease). 1.Vitamin B1 into too little The daily intake requirement of normal adult male is 1.2~1.5mg, female 1.0~1.1mg, related to energy demand, generally not less than 0.5mg/1000 kcal. Vitamin B1 is abundant in yeast, animal tissues, beans, peanuts, wheat and brown rice. Vitamin B1 can be lost after grain refining or improper storage and mold deterioration. Thiamin is a water-soluble vitamin, which is not resistant to high temperature under alkaline conditions, so it can be lost or destroyed by improper steaming and cooking with rice soup and vegetable soup. In addition, loss of appetite, heavy alcohol consumption, long-term intravenous nutrition patients can lead to insufficient intake of vitamin B1. 2.Increased demand Under physiological conditions, such as growth and development period, pregnancy and lactation, strong physical labor and exercise, or high carbohydrate, low fat, low protein diet structure, the demand for vitamin B1 increases. In pathological conditions, such as thyrotoxicosis, long-term fever, and chronic wasting diseases, the demand for vitamin B1 also increases. Vitamin B1 is absorbed in the small intestine in the form of passive diffusion and active transport according to the concentration, and the amount stored in the body is small. Chronic diarrhea, intestinal tuberculosis, intestinal typhoid and other diseases can cause vitamin B1 absorption disorders. Alcoholism, chronic malnutrition and folic acid deficiency also have absorption disorders. In addition to absorption disorders, patients with alcoholic liver disease also have intermediate metabolism disorders that transform thiamine into thiamine pyrophosphate. 4, increased catabolism Eating certain foods containing thiamin enzymes, such as raw fish, oysters, shrimp, coffee, tea and other plants, can oxidize the vitamin, so that the body thiamin levels drop. 5.Increased excretion The excretion of vitamin B1 in the urine is mainly in the form of thiamine itself (excreted by the renal tubules) and acetylated derivatives, thiazole acetate derivatives, etc. When diuretics are used, excessive loss of vitamin B1 can occur. In addition, vitamin B1 can also be lost during hemodialysis, peritoneal dialysis, or diarrhea.