My understanding is that Deplin increases the serotonin neurotransmitter sites.
Those antidepressants that are the SSRIs or selective serotonin reuptake inhibitors
hold serotonin within the brain cells longer, and I would think (though I
don't know this) that Deplin also may contribute to the increase of serotonin itself.
I believe 5htpTryptophan may be involved also--not just tryptophan; that
can't cross the blood-brain barrier.

Vitamin B9 or folate is a vitamin which the brain requires for serotonin effectiveness.
Without the ability (because of lacking the stomach enzymes) to transform folic acid
into a form of folate the brain can use, the brain just suffers excessive deficiency of
neurotransmitters that give the "good feeling tone". Prozac, which is an SSRI actually
works on other types of neurotransmitters, as well, so I suppose that it would be
wise to take an additional form of depression medication while one is taking a food med
especially designed for the serotonin neurotransmitter sites.

Deplin does its job nicely.