There are twenty amino acids in living organisms. ten of these are referred to as essential amino acids. why are they called essential amino acids?

Essential amino acids play vital role in various processes occuring in the body like energy production, nutrient absorption, tissue growth, immune function.

These are- Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine,  Threonine, Tryptophan, and Valine.

They are not synthesized by the human body. So they must be taken as supplements from the food. If body does not get these amino acids, the first response is the breakdown of muscle tissue. Thus, wastage of muscle is the first symptom associated with the deficiency of these amino acids. Other effects can include weakness, low immune response, and fatigue.

Therefore, they are called as essential amino acids.