Amino acids that cannot be synthesized by the body and must be obtained from diet are known as what?

Amino acids that cannot be synthesized by the body and must be obtained through the diet are referred to as essential amino acids. These amino acids are necessary for various physiological functions, including protein synthesis, tissue repair, and the production of hormones and neurotransmitters. Since the body lacks the ability to produce them, it relies entirely on dietary sources for these critical components.

In contrast, non-essential amino acids can be synthesized by the body, making them unnecessary to include in the diet. Conditional amino acids are typically non-essential but can become essential under certain stress conditions or illness. Supplemental amino acids are not a recognized category of amino acids but rather refer to amino acids provided through supplements to enhance intake. Thus, the classification of essential amino acids uniquely identifies those that must be sourced externally through food.