In my 20's, had a severe digestive disorder (mine was diverticulitis but I consider diverticulitis, colitis, and Crohn's to have the same root cause). Then for almost two years, I worked overseas. While I was abroad, I gave up my "American" diet and ate according to local traditions in an Asian country. After a few weeks, my digestive symptoms simply went away.
Why would symptoms disappear because I ate differently? When I returned home to the U.S., my symptoms came back with a vengeance. It became obvious to me that my diet that was the problem.
I researched and found that diverticular disease mainly exists in 7 countries. The other 180+ countries, with billions of people, have very few, to zero cases of diverticulitis. This is a fact. Here is what doctors at Cornell University said (paraphrased): 30% to 65% of the population in the “Western world countries” have this disease but it is almost nonexistent in the other 180! Here are the medical research citations: