Which type of amino acids must be obtained from the diet because they cannot be synthesized in the body?

Essential amino acids are those that cannot be synthesized by the body and must therefore be obtained through the diet. There are nine essential amino acids in humans, which play crucial roles in protein synthesis, hormone production, and various metabolic processes. Since the body lacks the necessary enzymes to produce these amino acids, they must be consumed through food sources such as meat, dairy, eggs, and certain plant-based proteins.

Non-essential amino acids, on the other hand, can be synthesized by the body and do not need to be obtained from dietary sources. Conditionally essential amino acids are typically synthesized by the body but may need to be supplied through the diet during certain conditions, such as illness or stress. The concept of semi-essential amino acids is less commonly recognized and often overlaps with the idea of conditionally essential amino acids.

Understanding the distinction between these categories of amino acids is essential for nutrition and health, as it highlights the importance of a balanced diet to ensure adequate intake of these vital components for body function and maintenance.