What are the two classes of amino acids in terms of their necessity in the diet?

Amino acids are categorized into two classes based on whether they are required in the diet: essential and non-essential. Essential amino acids are those that the body cannot synthesize on its own, meaning they must be obtained through dietary sources. There are nine essential amino acids, which include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. On the other hand, non-essential amino acids can be produced by the body, so it is not necessary to consume them through food. Examples of non-essential amino acids include alanine, aspartic acid, and glutamic acid. Understanding this classification is crucial for nutritional planning, as it highlights the importance of including a variety of protein sources in the diet to ensure adequate intake of essential amino acids, especially for individuals who may not consume animal products.