Awhile back, I wrote a few posts about some cast iron cookware that I've found in second-hand shops and have been restoring. One of you, my readers, commented that her daughter's doctor recommended cooking in cast iron as a way to get iron into her daughter's diet.
Being the scientific person I am, I was curious if this had any truth to it or if it was just an old wives tale. It didn't make sense to me that a well-seasoned pan would give off that much iron. So, I did some Googling, and here's what I found.
It turns out that cast iron will indeed leach a bit of iron into your food. However, how much iron ends up in your food depends on a combination of how well-seasoned your pan is and what you cook in it.
Seasoning is that shiny black patina that everyone wants their cast iron pans to have. A well-seasoned pan can be as slick as Teflon coated nonstick pans if the pan is well cared for. The seasoning is built-up over time as the oil from the foods you eat chemically bond with the pan surface. In general, the more seasoned your pan, the less actual iron is in contact with the food and the less iron will leach out of the pan into your food while cooking.
The other factor is the food that you cook in the pan. Cast iron reacts with acidic food and will leach into the food much more quickly. That's why most chefs warn against cooking tomato products in uncoated cast iron. The leaching of the iron into acidic foods is so heavy that the foods will have a metallic taste. If you have a really great seasoning on your pan, you can sometimes get away with cooking acidic foods in it. It's not unhealthy to do so. It's simply a matter of personal taste.
So here's the kicker. There are something like only two manufacturers of cast iron cookware left in this country and both only sell "pre-seasoned" pans now. The pre-seasoning process isn't perfect, but it helps you develop a really durable seasoning in your home much faster than if you started with a shiny silver pan. Unfortunatley, since all new pans are seasoned, you're not going to get much leaching of iron into the food.
So the answer is yes, you can use cast iron cookware to get more iron into your diet. However, you're probably not getting anything close to what an iron supplement would give you if your pan is seasoned as it should be.