Er - if one is not "regular" ought one not to change diet/fluid intake until one is?
It's not a question of regularity...it's a question of the build up of impacted and hardened, you know, that everyone on a western diet has that prevents the colon from doing it's work.
Irrigation sort of cleans the slate, levels the playing field, and gives the body the chance to do its own work to keep you healthy. It's a tool. Like all tools, it's not the only one for the job but can work with other tools such as proper diet and exercise to enhance the bodies natural ability to police and heal itself.
This makes sense to me and there's a body of work and research to back it up.