There are cast iron purists that cringe at the thought of lining a dutch oven with anything more than their favorite oil or shortening. Some consider it “cheating” if one is placing anything between the food being prepared and the well seasoned cast iron bottom of a dutch oven.
There are folks who say when one lines a dutch oven, the food doesn’t taste nearly as well as when cooked directly on the iron. There are those who believe that eating food cooked in cast iron can help with iron deficiency and that liners reduce that benefit. At the same time, some cooks would never use any tomato-based product in a dutch oven for fear of the acidity destroying the seasoning. For such recipes liners are a thought to consider. I am not one of those who gets too worked up over any of the above statements.
I think food tastes better when cooked in cast iron, however, my palate is not usually discerning enough to tell if a liner has been used or not.
As to the question about trace iron supplementation for one’s diet when using cast iron, there is research that seems to support this. That said, if one’s reason for cooking in cast iron is for that iron supplement, don’t use a liner. The other option is to use that liner where it makes sense and cook a whole lot of other food without a liner. That way you get the best of both worlds.
I don’t worry about tomatoes affecting the seasoning because I’m not storing acidic food in the pot. As long as I do my normal, post cooking routine that includes a good cleaning job, rinse, thorough drying, wiping the cook surface with a bit of oil, then back on the heat a bit, my seasoning seems to hold up very well.
Most of the time, when I have easy access to plenty of water and space to work for cleaning, I like to cook directly on the iron. I also don’t hesitate to use liners, inserts, or other pans in the oven when it makes sense to do so.
Cobbler in Parchment Liner 
Apple Dumplings 
Dumplings out to cool 
Pigs in a cornfield – simple cleaning – parchment paper liner 
Pesto Pasta Veggie Medley
simple cleaning w/parchment liner
I’ve found liners very helpful to me in a variety of settings. If cooking a sticky dessert like a dump cake or cobbler out in the woods where the water supply is limited, a layer of aluminum foil or parchment paper in the oven makes clean up a snap. Even if not in the woods when I’m cooking in multiple pots for dozens of folks, at the end of the day, I’m tired and while cleaning one pot is not a big deal, cleaning a half a dozen or more can sure make the idea of using a liner a lot more appealing.
I like the ease of removing items from the oven when baking. Cakes, breads, and cookies that need to be quickly removed from the heat when they get to that, “just right”, level of doneness seem to do much better for me when I use a parchment paper liner.
Cake layers – liner helps with quick removal for cooling 
Lil Smokies/Pigs in a blanket – liner for quick removal for multiple batch cooking 
Chocolate Chip Cookies – Liner for batch cooking, quick removal for cooling, and serving tray cover
Liners can also increase my cooking efficiency. If baking multiple batches of cookies, biscuits, or pigs in a blanket I can have an oven loaded with food on a parchment paper liner inside, another liner of food just recently pulled from an oven on a cooling rack, and one being prepped with a fresh batch ready to go to the heat. Quick loading and emptying of ovens can really help speed up a big breakfast and conserve heat and coals at the same time.
Cake in a Bundt Pan 
Cobbler in a cake pan 
Beer Bread Loaves 
Any pan used in the oven at home can also be a helpful tool for dutch oven cooking.
Sometimes a springform pan, loaf pan, cake pan, fluted pan or disposable serving pan adds a degree of flexibility to dutch oven cooking and I do not hesitate to use any of the above.
Just like any other project, the task seems to go best when using the right tool for the job. Along with using the right tool, personal preference is a huge factor in determining what one uses successfully. So use a liner or don’t use a liner. Either way, don’t miss out on good food coming out of a dutch oven!
