How do you know that the cast iron seasoning does not leach into your food? It is well established in the scientific literature that those cooking on stainless steel cookware get a portion of their daily iron intake from the iron in the pan that makes it into the food:


Geerligs, Brabin, and Omari, Food prepared in iron cooking pots as an intervention for reducing iron deficiency anaemia in developing countries: a systematic review, J Hum Nutr Diet. Aug 2003, Vol. 16, Num. 4, pp. 275-81.
Kollipara and Brittin, Increased iron content of some Indian foods due to cookware, American Dietetic Association. Journal of the American Dietetic Association, Vol. 96, Num. 5 (May 1996)
Kuligowski and Halperin,
Stainless steel cookware as a significant source of nickel, chromium, and iron, Arch. Environ. Contam. Toxicol. (1992) Vol. 23, Num. 211.


For most people that's not a bad additional nutrient, and those who saw family use a stainless steel pan surviving a lifetime know that the lost steel will not wear a pan out, not even after decades of use.

I'm now giving up on finding a tri-ply skillet whose bottom will remain perfectly flat. Since I cook on ceramic, a cast iron skillet is a good option. I'm hoping this would lead to steaks cooked perfectly evenly.

Suppose I'll use the cast iron skillet for literally just steaks, I'm concerned about the burned fat from the skillet's seasoning that will leach out to the steaks—in analogy with what happens when cooking in stainless steel cookware.

When you cook with cast iron, how do you know that some of the fat from the food you're cooking makes it to the skillet, but never the other way around. How do you know that the burnt pan "seasoning" does not make it into your food? Without some kind of confirmation that the burnt pan seasoning is safe, it would be nice to confirm that this does not occur in even trace amounts?

I'm guessing that deglazing the pan after cooking steaks would only increase the chance of this leaching in the undesirable direction. Hints for safe deglazing are also welcome.

update: A possible litmus test to determine potential leaching is to wipe with a paper towel.
Have you ever had the experience, when cooking in stainless steel, of the oils browning onto the edges of the pan?  You know, the brown gunk that is really tough to clean off...it usually takes a scrub pad, some elbow grease and some abrasive cleaner.  That is polymerized oil.  The idea behind seasoning a cast iron pan is to create a surface of polymerized oil. It's not burnt oils. It is really a pretty tough surface when done correctly.  On top of that you would typically add some fat (for example when searing), though that might not be necessary depending on your cooking method.  The idea that the seasoning would somehow contaminate your food is hard to imagine.  A well seasoned cast iron pan will generally hold up to deglazing...and even a light washing with soap and water.  This is how I think about it as an informed cook.  I would welcome a more informed response from any one with expertise in the actual science.