Which amino acid cannot be produced by the body?

Tryptophan is classified as an essential amino acid, meaning that it cannot be synthesized by the human body and must be obtained through dietary sources. Unlike non-essential amino acids, which the body can create from other compounds or amino acids, essential amino acids are critical for various physiological functions, including protein synthesis, hormone production, and neurotransmitter regulation. Tryptophan is particularly important as it serves as a precursor for serotonin, a key neurotransmitter that contributes to mood regulation. This distinction is vital in nutrition and dietetics, as understanding which amino acids are essential helps guide dietary recommendations and interventions to ensure adequate intake for optimal health.

Alanine, glycine, and tyrosine, on the other hand, can be synthesized by the body. Alanine and glycine are non-essential amino acids that arise from various metabolic processes, while tyrosine is synthesized from phenylalanine, another essential amino acid. Knowing which amino acids are essential versus non-essential is crucial for dietitians when devising nutritional plans tailored to individual needs.