There is now scientific proof that our immune system is mainly in our Gut. This article explains some of it.
I hover between the Thyroid forum and this PTSD forum on HU. I was apparently on the correct medication & dosage for my low thyroid, but I was left with PTSD, which I think was caused from all the decades of trauma, suicidal thoughts, near homelessness, my son on drugs etc etc.
I banished the PTSD symptoms by doing the AIP (auto immune paleo) diet.
Today, I do have some flashbacks due to about three horrible situations re-appearing in my life. But mainly I'm so so much better. I only followed the AIP diet for around 6 weeks.