From Amy Yasko Pathways to Recovery: "As mentioned, chronic bacterial infection also affects tryptophan breakdown, which is why those with chronic bacterial issues and CBS up regulations should limit intake of P5P. I’ve noted that in certain instances, the use of high dose B6 or P5P is not always helpful, and may cause overstimulatory or OCD type behaviors. While kynurenic acid is a calming neurotransmitter, it’s converted by B6 or P5P into quinolinic acid, which is an excitotoxin that can aggravate the nervous system. Increased levels of quinolinic acid have been implicated in Alzheimer’s disease and in excitotoxic damage of nerves. Quinolinic acid was found to be substantially elevated in patients with Borrelia burgdorferi (Lyme) infection and has been postulated that it contributes to the neurological and cognitive defects associated with Lyme disease"