As a sufferer of IBS (Irritable Bowel Syndrome), I've recently come across a thing called the "FODMAPs" diet - which is meant to relieve some of the symptoms of IBS. Something that none of the many treatments for IBS that I've been prescribed have managed.
Everything that I've read recommends consulting a nutritionist before starting on a FODMAPs diet - but that's a sensible step for anyone considering an exclusion diet.