How Much Iron Does Cast Iron Cookware Add to Your Food?
Cooking with cast iron can up the amount of iron found in your food. Here's how much iron you may be adding to your diet by cooking with cast iron pans.
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Cooking in cast iron can add a significant amount of iron to your diet. In studies, researchers found that spaghetti sauce cooked in cast iron skillets increased the iron content anywhere from 2mg to 5mg iron. This can be good news for those who don’t love iron-rich foods like beef and spinach, for vegetarians, or for those who may be at risk of deficiency like women and children. But is it good to get your iron from cookware? Here's what you need to know about cooking in cast iron for your health.
How Much Iron Do You Get Cooking with Cast Iron?
Women need 18mg iron daily (27mg in pregnancy), men need 8mg daily and children four to 13 years old need eight to 10mg, while teen boys need 11mg and teen girls need 15mg. For comparison, foods that contain higher amounts of iron include spinach (3mg), lentils (3mg), beef (2mg), tuna (1mg) and brown rice (1mg). But only animal sources of iron contain the better-absorbed heme iron which is absorbed at 15% to 35%; nonheme iron absorption rate is 2% to 20%, however eating vitamin C-rich foods can greatly increase the absorption of iron.
After reviewing several studies, scientists found that cooking in iron pots can impact iron status, significantly raising blood hemoglobin levels.
Cast iron cooking increases the nonheme iron content of foods. In one study, researchers looked at the amount of iron in 20 foods (3.5 oz portions of each) before and after cooking in cast iron pans. Most foods (90%) contained more iron when cooked in iron pans than in non-iron glassware. Researchers found that food with certain qualities contained more iron after cooking.
- More acidic foods: Often these foods are also high in vitamin C. Applesauce increased by about 7mg, and chili with meat and beans increased by about 5mg.
- Foods with more moisture: Scrambled eggs increased by about 3mg, but fried eggs only by about 1.5 mg.
- Foods cooked longer: More contact time appeared to up absorption; beef stew increased by 2.8mg of iron after cooking.
These foods were cooked in newer cookware which also added to the increased absorption of iron, compared with older, seasoned cast iron with its smooth, hardened surfaces.
A similar study was completed cooking both applesauce and spaghetti sauce in cast iron. Researchers found that the iron content of food was greater when food was cooked in cast iron — even when the cast iron had been used 50 times.
Is Getting Iron from Cast Iron Cookware Healthy?
The type of iron that comes from cast iron cooking is nonheme iron and is safe to consume. It is the same type of iron as found in plant sources such as beans, spinach and tofu.
Children one to three years old only need 7mg iron daily, so if it’s best not to cook every meal for children this age in cast iron cookware. That said, most children do not consume large portions of foods. The portions of applesauce and chili mentioned above were 1 cup servings. For comparison, here’s a list of iron-rich foods with serving sizes.
Which Foods Are Best to Cook in Cast Iron?
In culinary terms, cast iron holds heat very well. Batch-cook foods like pancakes (iron increased by almost 1mg after frying in cast iron). Searing meat works well since the dense metal won’t cool down when several pieces of cold meat are added. One-pan dinners that go from the stovetop to the oven are perfect for cast iron. A well-seasoned skillet is good for baking deep-dish pizza or cornbread.
While acid appears to help increase the iron content of foods cooked in cast iron, acidic foods cooked in cast iron can taste metallic. This is most common when foods are simmered for a long time. Our kitchen tests found that shakshuka cooked for about 20 minutes in cast iron did not have a metallic taste, but the same tomato-based dish cooked for more than 30 minute did have a little bit of tinny taste.
Find our 10 Favorite Foods to Cook in Cast Iron.
When cooked for a long time, some foods with high amounts of oxalates can react with cast iron and turn brown. These include rhubarb, spinach, and beets.
Bottom line: It can be safe for some people to up their iron intake cooking with cast iron.
A well-seasoned cast iron pan can be naturally non-stick, easier to clean, and impart small but meaningful amounts of iron into food. There are other variables like the amount of acid in food, the time food is cooked in cast iron, and the amount of moisture in food. But for people who need extra iron (many women and some children), cooking in cast iron is an inexpensive and easy way to up your intake.
Serena Ball, MS, RD is a registered dietitian nutritionist, food writer, and mom of five children. She blogs at TeaspoonOfSpice.com and is the author of the best-selling The 30-Minute Mediterranean Diet Cookbook, Easy Everyday Mediterranean Diet Cookbook and the forthcoming The Sustainable Mediterranean Diet Cookbook. Follow her @TspCurry on Twitter and Instagram.
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