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Crohns can vary dramatically in presentation and severity from minor annoyance symptoms to life-threatening catastrophies.
It is also possible your bud has IBS along with the Crohns, and that's why it has taken so long to find a good diet for him. Current thinking is that diet probably plays a minimal role in causing inflammatory bowel disease flares. Exceptions doubtless exist.
It's not clear what is going on with Gutz from the press releases but Crohns or UC are probably right up there based on age (though neither really fit with a "slow" digestive system.