My understanding is that if the body does not have enough vitamin b6 it cannot convert tryptophan into serotonin. B6 is also involved with dopamine levels too somehow.
http://lpi.oregonsta...mins/vitaminB6/Tyrtpophan is supposed to have some toxicity. To test for a B6 deficiency they can give you a
trytpophan load test to see if you excrete these metabolic waste products like xanthurenic acid in your urine.
"In people who are even marginally vitamin B6 deficient, tryptophan may be rapidly degraded into mildly toxic metabolites such as hydroxykynurenine, xanthurenic acid and hydroxyanthranilic acid. "
It is a sad fact that millions of scripts are written each year for SSRIs and none of these people are ever screened for a vitamin b6 deficiency. I have a b6 deficiency which was never diagnoses by any doctor.
A b6 deficiency will cause depression, anxiety, irriatability or even anger episodes, low energy, and little or no dream recall, among a lot of other things.