Amino acids that the body cannot synthesize on its own or at a rate that meets the body’s needs and must be obtained from dietary proteins are commonly referred to in nutritional science as essential amino acids. For adults, the main essential amino acids are: valine, tryptophan, threonine, lysine, methionine, leucine, isoleucine, and phenylalanine. Essential amino acids are often obtained from both animal and plant foods. Proteins in animal foods such as milk, eggs, fish and meat are rich in essential amino acids and have the right ratio, which is more suitable for the human body to supplement essential amino acids. Plant foods, such as oats and soybeans, also contain high quality proteins, which can be combined with animal foods for essential amino acid supplementation. It is recommended to have a balanced diet with a reasonable intake of milk, eggs, fish, meat, fresh fruits and vegetables to ensure the supply of essential amino acids in variety and quantity. If the deficiency of essential amino acids is serious, it is recommended to consult a doctor for treatment and supplementation under the guidance of the doctor.