Which of the following is a non-essential amino acid?

Arginine is categorized as a non-essential amino acid, meaning that the body can synthesize it and it does not necessarily need to be obtained through diet. Non-essential amino acids are those that the body can produce from other compounds, unlike essential amino acids, which must be acquired through food because the body cannot produce them on its own.

In the case of arginine, while it is classified as non-essential under normal circumstances, it can become conditionally essential in certain situations, such as during periods of rapid growth, illness, or physical stress, when the body’s requirements for arginine may exceed its ability to produce it.

Threonine and histidine are considered essential amino acids, as they cannot be manufactured by the body and must be acquired from dietary sources. Tyrosine, though it is classified as a non-essential amino acid, can be synthesized from phenylalanine, which is essential. This distinction is crucial in understanding the roles and classifications of amino acids within nutrition and metabolism.