Cysteine is considered a non-essential amino acid only in the presence of dietary
An amino acid is considered nonessential if it can be synthesized in humans, whereas it is considered essential if it must be obtained from the diet. Cysteine is derived from the essential amino acid methionine; therefore, cysteine can be produced in the body only if adequate dietary methionine is available. The 10 essential amino acids are phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, arginine, leucine, and lysine. Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 44
Methionine
Serine
Folate
Phenylalanine
vitamins