That is all speculations that doesn't line up with the dialog and we are never told that is what is happening. That doesn't change the fact that what we see onscreen makes no sense. You can explain away any plot hole or piece of bad writing if you come up with your own back story and just make stuff up out of thin air and while that may be fun that is not what we are told in any of the episodes. What we are told is that Kes is going to die because she turned nine,she wasn't in danger when she was eight and we are never told anything about the Caretaker or food being involved at all. It treated the same way old age is treated with anyone except it is treat as a fact that no one can live shorter or longer then ten years and that is just silly.

Yeah you can explain it away with stuff you make up in your own head but based on what we are told on the episode it's self this is what happens,once Kes turns nine she drops dead no question about it and it is a natural part of her people's lives.

If the writers wanted us to think it was the caretaker or the food then they should have put a line of dialog saying so in any episode with Kes in it. The writers had three years to give us this information if that was what was supposed to be going on and they didn't. if that was the intent then they are still hacks for not giving out information,and by the way that is a writer's job..giving the viewer or reader information. So in other words this was a huge fail on their part.