I have Sjogren's Syndrome-an autoimmune disorder that means that my immune system attacks my exocrine glands. That means that if the body depends upon fluid for it, then that system has a problem. Saliva, tears, and, yes, intestinal peristalsis.
Almost debilitating back pain a few years ago finally was diagnosed as another SS symptom-by my rheumatologist after my GP totally messed up. (Long story; he kept insisting that it had to be a muscle strain even while I demonstrated full out backbends. Learn to advocate for yourself!) As a consequence, I now take laxatives daily. BUT (that's kind of a bad pun, isn't it

)I can't take fiber! Fiber uses WATER to work-which is the source of my problems.
I use prescription lactulose-a sugar alcohol that flushes water through the intestine. My Dr. also tells me that if I forget my 'scrip, try overdosing on sugar free candy-yes, the sugar substitutes in many of them are sugar alcohols! Look for the "oses"-lactulose, maltolose, etc. If you live near a place that caters to the Atkins diet, that's what goes into their low carb sweets, because the body doesn't recognize these sweeteners as carbs and they get flushed right out.
Just another reminder that there are no one size fits all health solutions!
Kitty