I've heard some people have problems.
A quick Google later lead me to this.
An excerpt:
As with all artificial sweeteners, moderation is key. Keep in mind that, though sugar-derived calories may be absent, fat and calories from other ingredients are still out in full force in your favorite carb-free candy bar. In addition, sucralose [Splenda] and other artificial sweeteners are notorious for causing laxative effects — bloating, diarrhea, gas — in some snackers. This might be because the bacteria in our gut metabolize certain components of Splenda and produce a fun byproduct: nitrogen gas. Also, the excess of "stuff" sitting in the gut causes osmosis to kick in, bringing water into the colon, potentially causing some unpleasant diarrhea. |