What type of amino acids must be obtained through diet?

Essential amino acids are those that cannot be synthesized by the body and must therefore be obtained through the diet. There are nine essential amino acids that human beings require for proper functioning: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids play critical roles in various bodily functions, including protein synthesis, enzyme production, and supporting overall health.

Non-essential amino acids, in contrast, can be synthesized by the body, so they do not need to be obtained through dietary sources. Artificial and secondary amino acids do not accurately describe any known categories related to dietary requirements; thus, they are not relevant to the question regarding dietary needs for amino acids. Therefore, the focus on essential amino acids highlights the specific nutrients that must be included in a balanced diet to maintain health.