Each neurotransmitter is made from a specific amino acid through a series of steps that require specific nutrients (called cofactors). Taking these amino acids and cofactors is the only way to improve neurotransmitter levels and function in the brain because the neurotransmitters themselves cannot cross the blood-brain barrier.
The neurotransmitters that we are most concerned about are serotonin and the catecholamines (which include dopamine, norepinephrine and epinephrine). Serotonin is made from L-tryptophan and/or 5-hydroxytryptophan (5-HTP). The catecholamines are made from L-tyrosine and/or L-dopa.
Picture from Marty Hinz, MD: www.neuroassist.com
The important thing to note is that neurotransmitters cannot cross the blood-brain-barrier (this is depicted as the solid line in the above illustration. However, the individual amino acids (and the cofactors) can cross the blood-brain-barrier. Therefore, in order to raise the levels of neurotransmitters in the brain it is necessary to take the appropriate amino acids and cofactors AND facilitate their delivery across the blood-brain-barrier so they can be transformed into their respective neurotransmitters.
In theory, this is a fairly easy thing to do. It is a little bit more complicated in practice. How this can be best accomplished will be discussed in a future post.
