Amino Acids

Amino acids are the building blocks of proteins; hundreds of amino acids linked together to form a chain of polypeptides, which forms a protein. Human proteins contain +/- 20 kinds of amino acids. These proteins are necessary for the construction and functioning of an organism. Certain proteins are involved in building and strengthening of bones, nails, teeth, tendons etc. Others are needed for transporting oxygen, the immunity system and the hormone system.
Certain amino acids are turned into neurotransmitters in the brain, which are chemical substances that transmit impulses from one neuron to another. Naturally, different neurotransmitters induce different effects. If you lack certain neurotransmitters, it may lead to an altered state of mind.

All foods contain amino acids. However, they always contain a wide variety of amino acids, and those different amino acids compete with each other in crossing the blood/brain barrier.
Therefore, if you are trying to obtain the desired effect, it is better to take the amino acid in its pure form, and on an empty stomach. Do not exceed the amounts advised on the package, because more is not always better (the liver will just have to work harder). Some amino acids, like phenylalanine and tryptophan, cannot be produced by the body, and thus need to be part of nutrition.