Dr.NateNeph said:

My experience ordering cross-border ordering internationally: I've ordered from a UK pharmacy.

That reframing is the part I needed.

Adding the clinical framing, because it changes how the question reads. Order of operations matters more than any single choice here: establish a baseline, change one thing, wait long enough for it to express itself, then measure again under the same conditions.

Dr.GastroMayo said:

Start from the measurement rather than the conclusion.

I read this differently from Dr.GastroMayo, on substance rather than tone. I would resist the confidence. Half of what this board was certain about two years ago has since been quietly dropped, and nobody went back to correct the threads.

Adding the numbers, since they settle part of this. For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine. Half the figures circulating in this community trace back to a secondary summary that dropped a qualifier.

Moderator note: leaving this open. It is being argued well and the disagreement is the useful part. Thread quality here is what the rules are for. Keep it up.