If someone cares about what they're eating, I suggest the only reasonable strategy is to bring your own food. Even if UA told you what the ingredients were, you can't trust that information. There are far too many variables from source to plate, and it's not a priority for UA. Further, UA is notoriously pathetic about failing to honor special meal choices. So, you can't trust them to deliver what they promise. Therefore, if you want to eat, and it's important you control what you eat, you've got to bring your own food. With enough effort and creative planning, it's possible to design a TSA-proof meal plan that will last for 20 hours, and most trips don't last that long.