Which amino acid is classified as essential?

Histidine is classified as an essential amino acid because the human body cannot synthesize it; therefore, it must be obtained through the diet. Essential amino acids are crucial for various bodily functions, including protein synthesis, enzyme production, and supporting overall growth and development, particularly in infants and children.

In contrast, alanine, glutamic acid, and serine are considered non-essential amino acids. This means that the body can produce them through metabolic processes, so it is not necessary to obtain them from dietary sources. Non-essential amino acids still play important roles in health and metabolism, but their classification highlights the significance of dietary intake for essential amino acids like histidine.