I eat large quantities of fiber (due to massive grain intake, my biggest food source). While this has certainly kept me regular, I also get lots of gas. I'll sometimes have up to 40g or more of fiber per day (which is around or higher than the RDA). In fact, one package of Bear Naked natural granola contains 33g of fiber. Of course, too much fiber can cause, in some cases, less nutrients to be absorbed, and major bloating and gas, plus a lot of bathroom visits (not diarrhea, but lots of excessive but regular visits). However, I also drink natural juice purees, which contain immense quantities of nutritients (one for example had 1200% Vitamin E, and 280% Selenium, and 100% of many important B vitamins and other minerals). But, they also have fiber. However, plenty of healthy fibers from whole sources help greatly in improving regularity, cleaning out the intestinal tract, strengthening intestinal muscles, lowering LDL cholesterol, satisfying hunger, and reducing calorie and fat absorbtion. Anyway you look at it, fiber is a good thing. Too much only means discomfort, but from what research I have done, there aren't any medical concerns.