This thread goes back to 2008 with anecdotal experiences. Beware the Fiber One Fart Bars.

http://www.pleasegodno.com/archives/66-Fiber-One-Bars-make-me-Fart.html

I ate two in one day once. That was not a fun day.

Fiber one bars have some kind of ingredient in them that acts as a laxative. I learned this the hard way, when I ate 3 in a day. You will SEVERELY bloat. Get a ton of gas. Then massive cramping. Then get explosive diarrhea.

Was looking at some of their products the other day (brownies, gummies etc) and they're really not particularly high in fiber. It's junk food marketed as something healthy. Vegetables and water is what people need, not sugar.