In most cases, yes. It will usually say on the packet whether they are suitable or not. If it comes in granulated form (rather than little pills) then it is more than likely fine. I use sweetners all the time in cooking - the one I use is called Total Sweet Xylitol. The only occasion where I do not recommend it is when you are caramalising in a sauce pan as it does not tend to go brown, and just crystalizes once cooled.