Substantial improvement with (strange) dietary adjustments

[Wishful]

I don't think the sublingual route, if it exists, plays a significant role.

I was suggesting it as a test for solubility. Holding water-soluble chemicals in your mouth will get then into your bloodstream, even if you then spit out the food and rinse well. So, this might reveal whether it's a chemical in the food that affects you through the bloodstream, or if the food affects gut biochemistry. If it's fat-soluble, it should show no effect.