Solution: don't use "unsafe" Rust.

Oh stop you.

ah ah ah !

Actually what you need in your body is rust, i.e. iron ions.

Metallic iron cannot be used in any way by living beings, before it is oxidized to rust.

The leaked iron from cookware is already in the form of "rust", more precisely the iron is leached after it is oxidized to iron ions. The ions with 2 elementary charges remain dissolved in the water, and they may be absorbed by the body, while the iron ions with 3 elementary charges (these are the components of rust in the strict sense, i.e. of red iron oxide) will normally precipitate into red rust crystals, which will pass through the digestive tract mostly without being absorbed (a few might be reduced to ions with 2 charges, and then be absorbed).

I am not an expert but it seems that the form of iron absorbed by human body is ferrous sulfate, iron in +2 oxidation state. Iron rust of iron pan is in +3 state, which is chemically a different thing.

Your comment reminds me of the Lucky Iron Fish[0] developed in Cambodia as an iron supplement for populations plagued by iron-deficient anemia.

[0] https://en.wikipedia.org/wiki/Lucky_iron_fish

You beat me to this!

https://www.bbc.co.uk/news/health-32749629

You can buy them in the west now (even on Amazon I think):

https://luckyironfish.com/

I think a lot of the iron in the body is already in ionic form, so it's not a huge concern.