[zenkat]

Double-blind experiments are a great way to separate correlation and causation. See my (@zenkat's) wife's story above. Every so often, she accidentally and unknowingly eats foods she is sensitive to, and exhibits symptoms shortly afterwards. We go back and check the label and ... yep, there's the dairy/soy/yeast extract.

Oh, and there's no financially motivated third-parties here. We've done all this testing, elimination, and observation on our own.

[enziobodoni]

That's not a double blind experiment, but I'd agree it points to an intolerance. Actual experiments, I will reiterate, are hard to do. Have you tried feeding your wife food devoid of known triggers but told her they were in the food? I would hope not, because it's not an ethical thing to do, but you need that sort of thing to nail it down. Also, since she seems to accidentally eat food of unknown provenance, can you be sure the times she's gotten away with it without symptoms that the food in question was truly devoid of triggers? In others words, it is very very easy to confirm that things are bad for you, correctly or not.

[xorcist]

That's not a double blind experiment. I don't even know how to qualify it unless you at least have some data on how often those things the unknowingly eats that contains whatever she is sensitive against does not exhibit any reactions in her.