Classify Amino Acids Based on Nutritional Importance

Amino acids are classified into:

1. Essential (Indispensable) – Cannot be synthesized by the human body; must be obtained from diet.
   List (9 total): Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine.

2. Non-essential (Dispensable) – Can be synthesized by the body.
   Examples: Alanine, Aspartate, Asparagine, Glutamate, Serine.

3. Semi-essential (Conditionally essential) – Synthesized in limited amounts; required from diet during rapid growth or illness.
   Examples: Arginine, Cysteine, Glutamine, Glycine, Proline, Tyrosine.