Interesting. I've had a coworker hit a similar issue when bringing high value computer equipment* out of the country and back, and he was told to bring an invoice/receipt showing purchase in the United States in order to avoid duty. This looks like the alternative you'd want to do for that, if you didn't have the invoice.

Hard to imagine doing this with a bottle of pills, but I guess if you really need your scheduled medications it's better than the alternative.

(* the specific case was that we needed a very powerful server temporarily at a customer site in NZ for a few weeks, and it was not practical to lease one and set it up remotely. It was much easier and somewhat cheaper to send someone with it as personal baggage -- even with oversize and overweight fees -- and have him bring it in using a "temporary business materials" rule [I think this is also called carnet?] rather than send it Fedex and have it have to clear customs there unattended where they are likely to assume it will stay in the country. I volunteered for this, but my colleague was the more logical one to send. )

From what I can see, declaring a potentially problematic food item and being sent to the agricultural inspectors (are they also CBP, or are they USDA?) is bordering on a reliable (but time consuming) way to avoid other aspects of secondary.