It leaches iron. Not "heme iron" (like that found in meat), it isn't absorbed as easily.

This is affected by a number of factors including the acidity of the food, how new the pan is, and how the pan is seasoned

https://ift.onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2...

https://pubmed.ncbi.nlm.nih.gov/10073514/

Iron from the pan is not absorbed as easily as the iron in foods but it is still generally good for you rather than bad for you (like chromium).

If kids are low in iron, doctors still recommend cooking using iron pots & pans (in addition to supplements).

I found this related study interesting:

> Ethiopian children fed food from iron pots had lower rates of anaemia and better growth than children whose food was cooked in aluminium pots [1]

And to your point about Chromium, the type of iron leached by cast iron may not contribute to cardiovascular disease (the same way as heme iron) [2]

https://pubmed.ncbi.nlm.nih.gov/10073514/

https://pubmed.ncbi.nlm.nih.gov/25439662/

I cannot access the full-text of the second article, but is it really thought that heme iron is the component of red meat that contributes/causes cardiovascular disease?

Did the authors somehow adjust for the fact that a high heme iron intake generally implies a diet high in red meat?