Musing about cannibals

Trolls, as we have learned, are unfortunately inclined to indulge in a touch of cannibalism occasionally. One would hasten to add that not all trolls tend to lean towards eating their fellow trolls (or, indeed, humans, dwarves, elves ....) but there have been incidences where such atrocities have taken place.

Which gives one pause for thought - in a world that has a veritable population explosion, are trolls and their proclivities the answer to this problem?