If you eat a piece of food at the exact moment that you go through the nether portal, you will die. (and I don't mean that you are chewing it but instead are swallowing it at the exact second you teleport) You go through the portal and see that the next world is loading, but you can hear yourself suffocate as you load, and it takes a long time to load. Once you have loaded, you are dead and can see yourself looking out of the portal, but your items are nowhere to be found. If you have another person in your world, they can see your death cloud, but not you or your items. Even after mining the portal and all blocks surrounding it, your items are gone regardless. I was able to do this with bread and fish, but I haven't tried with other foods, though I don't think the type of food is what is causing the problem.

Xbox can't rollback servers so my items are gone for permanent. We can't switch to creative or we won't be able to get achievements anymore.