Which among the following are the essential amino acids?

Amino acids are the basic building blocks of proteins. Twenty amino acids make up proteins in living organisms; several hundred more amino acids perform specialized functions in human and non-human biology. Amino acids are often described as Essential (must be obtained directly from food) Non-essential (the human body is able to produce them on its own). Essential amino acids are not synthesised in the body so they are supplied in food for normal growth. The essential amino acids include isoleucine, leucine, threonine, lysine, methionine, phenylalanine, tryptophan and valine. Arginine and histidine are semi-essential amino acid while rest all are non essential amino acid. Ref: Janson L.W., Tischler M.E. (2012). Chapter 1. Amino Acids and Proteins. In L.W. Janson, M.E. Tischler (Eds), The Big Picture: Medical Biochemistry.