This issue also relates to copper, iron, selenium, boron, possibly iodine, and probably many other minerals.
The short story is that excess toxic forms of the minerals are accumulated either through supplementing incorrect/toxic forms, accumulating oxidized forms from free radical cascades, or in the case of calcium once it is pulled from bone to buffer acidity it becomes unuseable as a nutrient.
The iotards are playing with fire using Lugol'sIodine which may turn into a giant mess for them at some point in the future, and the same thing happened when selenium supplements first came out years ago with sodium selenite which is a toxic form of selenium. And I have warned about the same thing with silver users, we don't know what will happen in 10 or 20 years with them.
A good way to increase stomach acid is to borrow from people who were doing this sort of thing 5000 years ago and take ginger or ginger, cumin, lemon, and salt before meals. Also some people may not realize that certain supposedly healthy foods are not compatible with their chemistry and can interfere with stomach acid production.