Formation of non-essential amino acids in the human body

We cannot synthesize essential amino acids in the human body - Phe, Trp, Val, Leu, Ile, Met, Thr and Lys.
Two amino acids are essential during the growth period of the body (the period of their increased consumption), when the rate of their synthesis is not fast enough to cover the body's demands - called conditionally essential amino acids - Arg, His.
Other amino acids are classified as non-essential amino acids.

Amino acid precursors:

1) Oxalate → Asp, Asn;

(2) α-ketoglutarate → Glu, Gln, Pro, (Arg and His);

(3) Pyruvate → Ala;

4) 3-phosphoglycerate → Ser, Cys and Gly;

5) Phe → Tyr.