I don't wish to debate medical/biostatistics with you, but you're both picking the numbers wrong and not performing the analysis necessary to really define what food poisoning is (which is usually defined as food-borne illness of a known bacterial or viral nature). The actual estimate of foodborne cases of known etiology is 9.4 million. While it is likely that a small portion of the 38.4 million foodborne cases of unknown etiology meet the definition of food poisoning (a foodborne infection by known bacteria or virus), the vast majority of those are likely allergic reactions, hypersensitivities, sensitivities, correlation but not causation, or any other number of issues.

Further, one must consider the multiple stages at which airline food is cooked, frozen, and cooked again to be a limiting factor as to the likelihood that a case of food poisoning is actually what's happening here.

TLDR, statistically, it's unlikely. I'm not saying impossible - just that it's very unlikely.

If OP really feels they got food poisoning, go get it diagnosed with a causative agent and report the causative agent to United - then they can actually do something about it (testing catering facilities, corroborating with other reports). If OP simply says "yo UA, i felt sick after a flight" they're very likely going to file that straight into the "customer sent us an email that we can't do anything about" folder.