No poison or starvation flag?Suggestion

Just wondering if there is a way to make it so a player can't starve or poison themself to death.. I'm setting up a trap base for trolls on my PVE server so when they enter, the door closes..

They can't:
teleport, suicide, use chat, etc.. But I found if you poison your self or starve to death they can spawn in their own sleeping bag out of the zone. Is there a way that they would stay at like 1-5 health and never die?

I know the jail plugin does something like this but thats if the command is pushed on them. I want it so when they enter the zone they are F**KED!

Thank you.