Glutamine is hyped garbage IMO, but taking it shouldn't hurt you any, also taking creatine might make you gain some water weight, but with low carbs, I don't think the creatine will be as effective as it would be with moderate to high carbs. But to answer your original question, taking glutamine and creatine should be ok, my friend is on south beach and he takes both of them. BTW, I never do atkins or south beach, but when I'm cutting I lower my carbs, but to make sure I have energy I will have some carbs pre workout, also dextrose postworkout, but the rest of the day I avoid carbs. I got my bodyfat down to like 7 percent using my method. But I doubt you could do that on south beach, anyone on it know for sure?