Among them, essential amino acids include leucine, isoleucine, threonine, valine, lysine, methionine, phenylalanine, tryptophan, and histidine, which are required by the body but cannot be synthesized by the body and must be supplied by food. The rest of the amino acids that can be synthesized in the body and do not need to be supplied by food are called non-essential amino acids in nutrition. Essential amino acids can be obtained from food, such as lysine in peanuts and wheat, phenylalanine in tomatoes, and leucine and isoleucine in corn. For example, cereal protein contains less lysine and more tryptophan, while bean protein contains more lysine and less tryptophan, so mixing the two can increase the nutritional value of intake. In the case of certain diseases, a mixture of amino acids can be given to ensure that the patient’s organism needs amino acids to prevent deterioration. In general, proteins containing a large variety and high proportion of essential amino acids have a higher nutritional value, and vice versa, and animal proteins have a relatively high nutritional value because they contain a variety and proportion of essential amino acids similar to those needed by the human body. In addition, if a balanced diet is taken in daily life, with the intake of various vegetables and fruits, as well as meat, eggs and dairy products, a deficiency of essential amino acids in the body can be avoided.