You may be interested in this small, but somewhat intriguing study.
A case report of only four patients, none of whom had ME/CFS, but "a history of significant (sometimes severe) and repetitive inflammatory reactions including respiratory symptoms, joint pain, irritable bowel symptoms, muscular pain and enervation." Other symptoms are listed as well, including 'mental fatigue'.
The only time these patients suffered, was when the food product or products contained 'citric acid'. Even if the food was organic, but citric acid was used as a preservative. Citric acid is most often made from aspergillus niger, a mold.
They cut out all and anything that listed it as an ingredient, and all got better.
Don't want folks falling into another rabbit hole, but it just might help?
https://pmc.ncbi.nlm.nih.gov/articles/PMC6097542/