Of the 22 standard proteinogenic (also known as standard, normal, or primary) amino acids, 20 are directly encoded by the universal genetic code, with selenocysteine and pyrrolysine being incorporated into proteins by unique synthetic mechanisms. 8 are understood to be essential amino acids because the human body is unable to synthesise them from other compounds to meet the dietary requirements for normal growth, so they must be obtained from food.[1]

However, the situation is a little more complicated since cysteine, tyrosine, histidine and arginine are semi-essential amino acids in children, because the metabolic pathways that synthesise these amino acids are not fully developed.[2] The amounts required also depend on the age and health of the individual, so it is hard to make general statements about the dietary requirement for some amino acids.

Essential Nonessential
Isoleucine Alanine
Leucine Asparagine
Lysine Aspartate
Methionine Cysteine*
Phenylalanine Glutamate
Threonine Glutamine*
Tryptophan Glycine*
Valine Proline*
Arginine* Serine*
Histidine* Taurine

*These are known as conditionally essential.[3],[4]

Related products available at Nutri-Link:

Code Product description Type Size Supplier
72810 5-L-Hydroxytryptophan Caps 150 ARG
70650 Acetyl-L-Carnitine, 250mg Caps 60 ARG
70660 Acetyl-L-Carnitine, 500mg Caps 100 ARG
5223 Amino Acid Quick-Sorb™ Liq 60ml BRC
5237 Amino Sport™ Caps 180 BRC
72890 Arthred® Collagen Formula (VAT Exempt) Pwdr 240g ARG
764100 Arthred® Collagen Formula (VAT Exempt) Pwdr 900g ARG
7707 Casein Concentrate (form. De-Stress™) Caps 30 BRC
5221 DL-Phenylalanine Caps 100 BRC
12101 DNZ-2 100mg Caps 100 BT
12301 DNZ-2 250mg Caps 100 BT
70540 Free Aminos Caps 100 ARG
6502 GamOctaPro™ Powder (VAT Exempt) Pwdr 454g BRC
73900 ImmunoPro® Rx (VAT Exempt) Pwdr 300g ARG
5201 L-Arginine Caps 100 BRC
73910 L-Arginine, 500mg Caps 250 ARG
70580 L-Arginine, 500mg Caps 100 ARG
5225 L-Carnitine HCL Caps 30 BRC
5229 L-Carnitine Powder Pwdr 100g BRC
73930 L-Carnitine, 500mg Tabs 250 ARG
74760 L-Citrulline Pwdr 100g ARG
5211 L-Glutamine Caps 180 BRC
72130 L-Glutamine Pwdr 200g ARG
5209 L-Glutamine Powder Pwdr 500g BRC
71970 L-Glutamine, 500mg Caps 100 ARG
5202 L-Lysine HCl Caps 100 BRC
70600 L-Lysine, 500mg Caps 100 ARG
70610 L-Methionine, 500mg Caps 100 ARG
76100 L-Ornithine-L-Aspartate Pwdr 100g ARG
70630 L-Tyrosine, 500mg Caps 100 ARG
1271 Methionine-200™ Caps 100 BRC
71370 NAC (N-Acetyl-L-Cysteine), 500mg Tabs 120 ARG
6349 Neuro-5-HTP Plus™ Caps 90 BRC
93680 Premium Whey Protein (VAT Exempt) Pwdr 454g PMN
75600 RenewPro™ (VAT Exempt) Pwdr 300g ARG
6425 Rice Protein Concentrate (VAT Exempt) Pwdr 680g BRC
76020 Seratonin™ Caps 90 ARG
70620 Taurine, 500 mg Caps 100 ARG
6420 Whey Protein Isolate (VAT Exempt) Pwdr 454g BRC


  1. Young VR (1994). “Adult amino acid requirements: the case for a major revision in current recommendations”. J. Nutr. 124 (8 Suppl): 1517S-1523S. View Abstract
  2. Fürst P, Stehle P (2004). “What are the essential elements needed for the determination of amino acid requirements in humans?”. J. Nutr. 134 (6 Suppl): 1558S-1565S. View Abstract
  3. Reeds PJ (2000). “Dispensable and indispensable amino acids for humans”. J. Nutr. 130 (7): 1835S-40S. View Abstract
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