Mayo's GI doctor told me that any HOT drink would do it. I use tea and it's the first thing I consume in the morning. It stimulates the vagus nerve.
http://en.wikipedia.org/wiki/Vagus_nerve The vagus nerve stimulates the peristalsis (as I understand it). Peristalsis is the movement of the bowel that the body does automatically. And then, make time to spend in the bathroom. Make it a regular habit. I find that if anything interrupts this "schedule", it will cause a problem. But I just make time for it as often as is possible. And sometimes later in the day if I've had to miss the morning window of opportunity, I can have an afternoon cup of hot tea and still stimulate things to work.
Billye