It was done with cooking oil at one time. Problem is it gave most of the test subjects diarrhea after eating a bag of potato chips that were fried in it. Of course anyone that eats a bag of potato chips is at risk of that anyway...
I replied to your post because I started having similar troubles, went to the doc and I tested positive in several issues, being the main one that I have Fructose intolerance.
That was when I learned about FODMAP, and I learned about the work Monash University is doing on that field: https://www.monashfodmap.com/
Hope that helps, but better if you don't need them!