You are describing the behavior of a preparation in a dish where you CAN alter the concentration of Zinc. In the interstitial space you can’t. The article I linked above is the most comprehensive article I have ever seen on “Zinc Metabolism”.
Look at it this way, something more people are familiar with. Sodium metabolism. “How much table salt would you have to ingest to raise your interstitial Sodium level (Na+) from 140 mole per deciliter to 141?” The answer is you pretty much can’t do it. You will just put a lot more Na in your urine.
Deficiency states for NA work pretty much the same for Zinc, you have two pools of “reserves” from which to mobilize, a “Readily mobilizable pool” and a “Not Readily mobilizable pool” that is much larger because it is BONE.
IOW you will repair a deficiency of Na or Zn much faster from these pools than your diet. Or Supplement.
RE: IOW you will repair a deficiency of Na or Zn much faster from these pools than your diet. Or Supplement.
So, bottom line — Supplements of ANY kind are pretty useless?