True that. It is easy to see workmates who are intollerent though, just feed them some wheat products and watch them go for some antacit 2 hours later while they are burping and farting everywhere
A lot of that is people who avoid a certain food for a period of time then the stomach takes some adjusting to get used to that food when you reintroduce it. Not an actual intolerance.
The prime example for most of us is the first time you have protein power. The worst farts ever. Now most people never have any issues.