What are essential amino acids?

Essential amino acids are specific amino acids that the human body cannot synthesize on its own. As a result, they must be obtained through dietary sources. There are nine essential amino acids for adults: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The body relies on these amino acids to build proteins, which are crucial for various biological functions including cellular repair, immune response, and the production of enzymes and hormones.

In contrast, non-essential amino acids are those that the body can produce, meaning dietary intake is not strictly necessary for survival. Options discussing amino acids produced during digestion or those necessary for energy metabolism do not accurately encompass the concept of essential amino acids as they do not focus on the necessity for dietary intake. Therefore, the definition highlights the critical nature of sourcing these amino acids from food to ensure proper bodily functions.