Yes, and no. If you are not accustomed to a high-fiber diet, getting there too fast is apt to result in, to put it delicately, gastrointestinal duress. Even after you acclimate, you may find that you are using the restroom more often that before. That may not be a problem- the medical missionary Dennis Burkett famously noted that 'by world standards, the entire U.S. population is constipated.'

Very high fiber intake can interfere with absorption of some vitamins and minerals- calcium often gets top billing here. And rapid GI transit can lower absorption of fat soluble vitamins slightly. So, along with a high intake of fiber, eating nutrient-dense, natural foods- and/or taking supplements- is apt to be prudent.

As for the up side: studies in diabetes and those at risk of diabetes have shown dramatic metabolic benefits with fiber intake of 50 grams a day. That is as much as twice the current RDA for adults. Dr. David Jenkins at the University of Toronto conducted a study of the 'portfolio' diet that included 75 grams of fiber (much of it soluble, less of it insoluble) daily- and demonstrated the regimen could lower LDL cholesterol as much as statin drugs! (The regimen also included 2 grams daily of plant sterols.)

Finally- paleoanthropologists estimate that our Stone Age ancestors consumed roughly 100 grams of fiber daily, suggesting that our systems are adapted to handle that.

So while it is possible to eat 'too much' fiber for comfort, it is unlikely to eat too much for health. Most of us eat far too little, so that is clearly the more present danger.

Build up slowly, take nutrient rich foods and judicious supplements along with you, cut back a bit if you overshoot and pay the price- but within bounds of reason, go for it. Benefit is likely, risk remote.