Of the twenty amino acids, ten are considered ‘essential’ amino acids. The term ‘essential’ may cause confusion – in biological terms, ‘essential’ nutrients are those that the body can not manufacture from other components. They are ‘essential’ to the diet – in the sense that they must be consumed in some form every day because the body has no other way to obtain them.

Those ten essential amino acids are arginine (required for the young, but not for adults), histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. If the body isn’t fed enough of even one essential amino acid for its energy, it will begin to deconstruct its own tissues to obtain it.

The other ten amino acids are no less essential to the functioning of the body – but they are considered ‘non-essential’ amino acids because the body can synthesize them from other amino acids and ingredients. Those amino acids are alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine. While the body can synthesize these, it must have the right ingredients to do so. Because tyrosine is made from phenylalanine, for instance, if your diet is lacking phenylalanine then your body won’t have enough tyrosine either.

All of the amino acids are found in animal products as proteins – but your body can’t use the proteins as they are. It must first break down each protein into its component amino acids, then put them back together into protein that it can use. In addition, because all amino acids fit together into proteins in specific combinations with specific proportions, your body’s ability to make any particular protein is limited by the amino acid that it has in least supply.

One of the best ways to illustrate ‘limiting amino acid’ is to think of a recipe for baking a cake. You need eggs, flour, milk, sugar and baking powder. You may have 40 pounds of flour, five of sugar and fifty gallons of milk, but if you only have two eggs, you can only make one cake.

Likewise, if your diet is rich in tryptophan but lacking in lysine, your body’s ability to make use of the tryptophan is limited by the amount of lysine it has available. Since tryptophan is needed by your body to make use of vitamin B6, a deficiency of tryptophan can lead to a deficiency of B6. While ‘protein deficiency’ is rare outside famine areas, your body can become depleted of particular amino acids through trauma, infection, stress, medication side effects, aging and chemical imbalances. The result can be cold sores, outbreaks of herpes, fatigue, reduced metabolism, insomnia, hair-skin-and-nail problems, undue stress and poor health in general.

The best way to get sufficient protein and amino efforts is through the foods that you eat, but supplements of specific amino acids can help your body utilize all of the nutrients that you eat more efficiently. Specific amino acid supplements have been shown effective in clinical trials in alleviating depression, helping to protect against heart disease, preventing blindness due to aging and macular degeneration and more. As always, before taking any supplements consult your doctor for his or her recommendations.