The science on irritable bowels is clear as day: Meds do absolutely nothing for this condition.

Yet docs keep dishing them out anyway. And when one doesn't work, they'll try another... and another... and another.

It's a waste of everyone's time -- and meanwhile, your bowels are not only madder than ever, you're battling drug side effects to boot.

Now, new research confirms what I've been telling you all along: Low vitamin D levels play a critical role in any number of bowel disorders, including Crohn's disease and ulcerative colitis.

Americans who live in the sun-soaked south are 52 percent less likely to come down with Crohn's and 38 percent less likely to get hit with ulcerative colitis than folks who live up north, according to the study in the journal Gut.

This gels with other studies, which find that Crohn's is rare in the sunniest climes along the equator, and gets more common the further north you go (Sorry, Canada).

Of course, there's a lot more to a healthy gut than adequate vitamin D levels. Naturally, diet plays a major role as well.

The best way to find out which foods are behind your pain is with a food elimination diet -- a painstaking and time-consuming diet that involves starting with almost nothing and then slowly adding foods to see which ones send you running for the toilet.

I won't lie -- it's a lot of work. If you're not ready to go through all that, try my shortcut: I had the inside scoop on the five ingredients most likely to cause bowel trouble in the December 2010 issue of my Douglass Report newsletter. Click here to get all the details.