Any data out there on the amount of iron transferred into food when cooking with cast iron cook ware?
Does the act of seasoning the cast iron (coating it in oil) prevent or diminish iron's capacity to leach into food during cooking?
-- Nicole Journault
[City Unknown], Canada
One of the most thorough studies on this topic, conducted by Brittin and Nossaman, was published in 1986 in the Journal of the American Dietetic Association.
The conclusion? "Acidity, moisture content, and cooking time of food significantly affected the iron content of food cooked in iron utensils."
It is a well established fact that cooking in cast iron cookware will transfer some iron into your food, especially if the food contains high amounts of vitamin C and moisture and is stirred or turned over frequently.
In terms of figures, cooking half a cup of spaghetti sauce in an iron pot for 15 minutes increases its iron content by approximately 800 percent. Foods low in moisture and vitamin C, however, increase by anywhere from 80 to 150 percent.
Keep in mind that these figures depend on how long you cook these foods for.
The "catch 22" is that iron cookware often imparts a strong metallic taste to foods -- especially those high in vitamin C and moisture cooked for long periods of time!
Three more important points:
1) Coating the cookware in oil prevents iron's leaching capacities.
2) Iron absorption gradually decreases with each passing use.
3) Since iron cookware only increases the iron content of non-heme iron, meats are unaffected.