What type of amino acids must be obtained through diet?

Essential amino acids are those that the body cannot synthesize on its own and, therefore, must be obtained through the diet. There are nine amino acids classified as essential: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids are vital for various bodily functions, including protein synthesis, hormone production, and enzyme activity.

In contrast, non-essential amino acids can be produced by the body, meaning they do not need to be consumed through food. Conditional amino acids are usually non-essential, but in certain conditions like illness or stress, the body may need to obtain them from dietary sources. Transitional amino acids are not a recognized category in standard amino acid classification. Understanding the distinction among these categories highlights the importance of including a variety of protein sources in the diet to ensure adequate intake of all essential amino acids.