Plant protein supplementation is preferred in patients with hepatic encephalopathy, and the amount of protein supplementation varies depending on the severity of the disease. Plant proteins are rich in branched-chain amino acids, non-absorbable fibers, and can promote ammonia excretion after fermentation and acid production by intestinal bacteria. For acute onset of hepatic encephalopathy, protein should be forbidden for several days, and should be limited to less than 20g per day if it is stage 1~2 hepatic encephalopathy to avoid aggravation of the disease. When the patient recovers from waking up, the amount of protein intake should be gradually increased from 20g per day to 1g per kg body weight of the patient per day (e.g., if the patient’s body weight is 60kg, the amount of protein intake should be 60g per day). Patients with chronic hepatic encephalopathy generally do not need protein supplementation. In addition to this, they should be supplied with adequate amounts of calories, various vitamins, and plasma or albumin as appropriate.