If you are engulfed by the planet as soon as you step foot on it the question of whether they provide adaquate nutrition is rather moot. Mind you, if you, all other surface dwelling life, and presumably most of the scenery have sunk into the planet, can it truly be said to be made of sandwiches any more?
Imagine if you will the absolute carnage wrought by your sugar-loving gut biome once you take that first dump on this pbj planet (assuming you don’t sink in).
How long do you think you’ve got before the whole thing spoils and you die of sepsis from living in rot? Think you could outrun it on a daily basis to stay alive?
I think it would depend on the ratio of jam to peanut butter and bread. High sugar concentrations are an excellent way of preventing bacterial growth as it acts as a desiccant which is why jam can last so long without spoiling. So, unless there's enough moisture in the peanut butter and bread, your discarded gut bacteria will die out. It turns out that too much of a good thing really can be bad for you.
