Prostate-focused EBRT causes diarrhea, to some degree or another, in most if
not all people.  In my case, I was drinking liters of water daily, so the
damage wasn't that bad.  It still caught up with me eventually.  I had been
taking Metamucil to elminiate constipation.  Metamucil no longer became
necessary.  The diarrhea never became serious.  After EBRT, constipation and
Metamucil returned -- no worse.... no better.

I'm getting a RRP (and a colon resection) in a couple of weeks, but
consulted a radiation oncologist before committing to the RRP for a reality
check after seeing several surgeons and reading a bunch of books by
surgeons -- every one biased towards surgery. When the radiation weenie saw
that I already had some IBS and an overactive bladder, she said . . . CUT!
Radiation tends to exacerbate existing urinary and colon problems long term,
she (and the books) said, and I DON'T need that!

But while we're on the topic, are you aware that many cases of "IBS" are
self-inflicted and easily cured almost overnight, free, almost permanently,
by yourself? White Bread. Too much white bread, aka plugs, including pasta,
white rice, so-called "wheat bread", junk food made from white bread, etc.
That's bad enough, but coupled with insufficient fluid intake it's a
nightmare. Hint: ever roll up a ball of Wonder Bread, pack it tightly, and
bounce it off a wall? The dang stuff can be DRIBBLED like a Superball! Now
imagine that in your gut.

Since I quit eating any bread or pasta whose first ingredient is not "whole
wheat", my IBS went away, about 15 years ago. I can make it return any time
by eating much bread in a seafood restaurant (it's always white bread
sourdough), restaurant pasta (always white bread), etc. "Wheat Bread"? Look
at the ingredients: it's NOT whole wheat; it's man-made white bread with a
dash of molasses or food coloring to LOOK like whole wheat. Another
gauranteed relapse for me is to stuff my face at a buffet and forget to CRAM
down fluids the entire rest of the day.

If the notion of self-inflicted -- and self-healing from -- IBS intrigues
you, there's more available on the 'net from reliable sources. OTOH, I don't
NEED reliability for an experiment so simple, logical, cheap, and safe.

I.P.