I think of it as another important marker for health. You can add a GSH test to a blood test & if low, supplement like any other vitamin or nutrient.

I can't understand why doctors with traditional training don't just say "I have little training in nutrition - go ask someone with more experience & info" !! That's why I suggest having an ND on your CF team - a supplement expert can really help manage the malabsorption situation caused by CF. (...it is not just A,D,E,K !)