There are more than 50 Amino Acids which have been identified by scientists and each is a little different. Amino Acids are used to build protein - protein helps to support the maintenance of muscle mass and normal bones. Although 50 amino acids have been identified, only 20 of them are used by the human body. Of these 20 amino acids, 9 are classed as Essential Amino Acids. This means that the body cannot make them, we must get them from our diet, by eating protein rich foods. The essential' amino acids are: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan & Valine. , , Other amino acids are classed as conditional amino acids' this means that generally they are not essential, except in times of illness & stress. Conditional' Amino Acids include: Arginine, Cysteine, Glutamine, Glycine, Proline, Serine & Tyrosine. When taking an amino acid supplement, it is suggested that you take it away from food - either half an hour before you eat or at least an hour after. ARGININE: Each Natures Aid L-Arginine tablet contains 750mg L-Arginine Hydrochloride, providing 620mg L-Arginine. These tablets are suitable for vegetarians., , Directions for Use: Take 1-3 tablets per day on an empty stomach. Do not exceed the recommended intake