I think I asked and am awaiting a reply.
The thing is if it isn't in the book, technically it's not allowed. Things that aren't allowed are either not allowed because they will have a detrimental affect on the diet or because they haven't been tested.
I have in times of desparation had some sugar free jelly. And no limbs have subsequently dropped off, it hasn't hindered my ability to get into ketosis and it hasn't slowed my weight loss down. But at the moment I think probably the official answer is no answering from a CDC point of view.
It's a personal choice one. It you start feeling hungry and you stop losing weight - it's not for you.