Are Cast Iron Skillets a Safe Source of Iron?
Iron Leaching, Absorption, and Your Health
Hello and happy Thursday, health heroes!
Today is a special day — I held Health Shift in my hands for the first time! It’s hard to explain the feeling of seeing an idea materialize into something physical—something you can touch, flip through, and hand to another person. It’s like having a baby - I’m so proud, yet I’m still experiencing the pain and anguish of the hard work behind it. But it was worth it, 100%.
This book is about clarity. It’s a guide for those moments when you find yourself swimming in health advice, articles, posts, warnings, and hacks—and you’re not quite sure what to believe. Whether you’re deciding between supplements, diets, or yes, cookware—your decisions deserve a filter grounded in science, not hype. When we pause, consider the science, and apply logic instead of jumping to conclusions.
So, today, with my book in one hand and a question in the other, I started thinking about the latest trend of people cooking with cast-iron skillets.
It’s not so much about the skillet, though, but about iron. Do we really need iron from cast-iron skillets, and what should we know before switching all our cookware to cast iron?
Let’s sort through this the Health Shift way.
What Iron Does in the Human Body
Iron is a trace mineral.
What does that mean? We only need minute amounts. Highly sophisticated technology is required to measure such small quantities in both food and body tissues. But don’t let the term trace fool you—it’s essential to human life. Its primary role is in oxygen transport, forming the central atom in hemoglobin, which is found in red blood cells, and myoglobin, which is found in muscle tissue. Without iron, oxygen cannot be transported efficiently through the body, making iron indispensable for energy production, endurance, and basic survival.
Iron also supports:
DNA synthesis
Cellular respiration
Neurological development (especially during childhood)
Immune function
Thyroid hormone metabolism
Because of its broad involvement across systems, iron deficiency can present with a range of symptoms, including fatigue, pallor, weakness, brain fog, cold intolerance, brittle nails, and shortness of breath, among others. The body uses several mechanisms to regulate iron absorption. Controlling absorption is essential because our bodies cannot easily eliminate excess iron once it has been absorbed. Iron absorption from foods is about 18% of that present in healthy people, and somewhat higher in people with iron deficiency.
But having too much iron—yes, it happens—can be equally damaging. More on that in a moment.
Heme vs. Non-Heme Iron: What's the Difference?
Iron exists in two dietary forms: heme iron and non-heme iron.
Heme iron is found in animal products—particularly red meat, poultry, and fish. It’s absorbed through a specific transport system in the gut and is highly bioavailable, with absorption rates around 15–35%.
Non-heme iron is found in plant foods, eggs, dairy, and cast iron cookware. Its absorption is significantly lower—2 to 20%, depending on a variety of factors.
And here’s where things get more complex.
Factors That Inhibit (or Enhance) Non-Heme Iron Absorption
Like I just mentioned, non-heme iron is less efficiently absorbed by the body. It is also highly susceptible to dietary inhibitors:
Phytates – Found in whole grains, legumes, seeds, and bran. These bind iron and reduce its uptake.
Polyphenols – Found in tea, coffee, red wine, and some fruits and vegetables. These reduce non-heme iron absorption significantly when consumed with meals.
Oxalates – Present in spinach, beets, rhubarb, and some nuts, also bind to iron and limit absorption.
Calcium – Competes with iron for absorption at the intestinal level.
The biggest enhancer of non-heme iron absorption is Vitamin C. Just 50 mg of vitamin C with a meal can dramatically increase uptake of non-heme iron. This is why pairing iron-rich plant foods with citrus, tomatoes, or bell peppers is often recommended.
Now, let’s connect this to the cast-iron question.
Cooking With Cast Iron: Does It Meaningfully Increase Iron Intake?
Yes, iron leaches into food during cooking—especially when the food is:
Acidic (tomatoes, vinegar-based sauces)
Moist (soups, stews)
Cooked over longer periods
Stirred frequently (abrasion increases transfer)
Studies have shown that iron content can increase by 2–5 mg per serving when using cast iron, depending on the food, acidity, and cooking duration. For context, that’s potentially 20% to nearly 60% of the RDA for some individuals.
But is this iron actually usable by the body?
Since it’s non-heme iron, it still depends on the rest of your meal. If you’re eating that cast-iron chili with a slice of high-phytate cornbread and a glass of iced tea, you may be canceling out a good portion of what leached in.
When you first use a cast iron skillet—especially a new or lightly seasoned one—it releases more iron into the food. That’s because the iron surface is relatively exposed, and the food (especially if it's acidic or has moisture) comes into direct contact with the metal.
But over time, as you cook with fats and oils, you build up what's known as a polymerized seasoning layer—a hard, carbonized coating created when fats are heated past their smoke point. This layer acts like a natural, non-stick barrier and also physically separates food from the raw iron surface.
The better seasoned the pan, the less contact your food has with the iron, which means less leaching.
A few factors still matter, even in a well-seasoned skillet:
Acidic foods (like tomatoes or vinegar-based dishes) can still break through the seasoning and promote some leaching, even in older skillets.
Scrubbing or using soap too aggressively can thin or strip the seasoning layer, increasing iron exposure again.
Long cook times and high moisture levels, such as in soups and stews, also increase the leaching potential.
So, iron release lessens over time, but it doesn’t disappear entirely, especially if the pan is used in a way that wears down or disrupts the seasoning layer.
So I permit people to scrub their cast-iron pans now and then, even though many cast-iron officianados may balk at that suggestion. If you’re using cast-iron as a health intervention, tell them that it increases the leaching capacity of the iron.
Recommended Dietary Allowance (RDA) for Iron
According to the National Institutes of Health (NIH):
Men (19–50 years): 8 mg/day
Women (19–50 years): 18 mg/day
Pregnant women: 27 mg/day
Postmenopausal women: 8 mg/day
Women of reproductive age have higher needs due to monthly blood loss. Vegetarians and vegans typically require 1.8x more iron intake because they consume only non-heme sources.
Most individuals eating a diverse diet with animal protein, legumes, whole grains, fruits, and vegetables can meet their iron needs without supplementation—or cookware-based interventions.
Dietary Sources of Iron
Let’s ground this with actual food sources of iron:
Heme Iron Sources:
Beef, lamb, pork, liver
Chicken, turkey (especially dark meat)
Tuna, sardines, shellfish (clams, mussels)
Non-Heme Iron Sources:
Lentils, chickpeas, tofu
Spinach, kale, collard greens
Fortified cereals and grains
Quinoa, oats
Pumpkin seeds, sesame seeds, almonds
Dried fruit (apricots, raisins)
What Happens If We Get Too Much Iron?
Unlike water-soluble nutrients (like vitamin C), excess iron is not excreted through urine. The body has no reliable pathway for iron elimination, aside from blood loss.
Excess iron is stored in organs, especially the liver, pancreas, heart, and even the thyroid. Over time, this can lead to oxidative stress, tissue damage, and dysfunction of those systems.
A genetic condition called hereditary hemochromatosis affects about 1 in 200 people of European descent. It causes excessive iron absorption regardless of dietary intake. Many people are unaware they have it until symptoms develop—chronic fatigue, joint pain, skin pigmentation changes, liver enzyme elevation, or even diabetes.
In these individuals, regular use of cast iron or unnecessary supplementation could be harmful. Iron overload is diagnosed through laboratory tests, such as serum ferritin and transferrin saturation. If you're unsure about your iron levels, a simple blood test can provide valuable insight. That should be the first step in assessing whether cast-iron cookware should be used as a health tool or a cooking tool.
So... Should You Cook with Cast Iron?
It depends on whether it makes sense within your personal context. Cast iron is excellent cookware - I love it. It retains heat well, is naturally non-stick when seasoned properly, and is free from the synthetic coatings found in non-stick pans, many of which are undergoing reformulation due to mounting health concerns.
Yes, cast iron can be a subtle source of non-heme iron, but it’s not a universal fix. It’s just a tool. Not everyone needs extra iron. And not everyone will absorb what they get from it.
If you’re iron-deficient, cooking in cast iron—alongside a vitamin C-rich diet—might help increase intake in a gentle, food-based way. But if your iron levels are normal or elevated, there's no strong health argument to use cast iron solely for its iron content. Decide - is the cast-iron a cooking tool, a health tool, or both? If you plan to use it as a health tool, adjust your expectations based on your health status and cooking approach. Treat it as a health tool, and monitor your iron levels periodically. Treat it like a serious health intervention to prevent excessive iron intake.
The Bigger Picture
The real story here isn’t just about cookware. It’s about discernment.
There’s a trend right now of embracing old ways of living as if they are inherently better. Much of that is valuable and healthful. Some of it is performative. And some of it—like cooking every meal in cast iron for the iron content—is somewhere in the gray.
If you're navigating health decisions like these—do I need this? Will it help me? Could it hurt me?—Congratulations! You are asking the right questions. That is one of the primary purposes behind my book Health Shift. It’s not about being for or against interventions like this one. It’s about asking better questions, checking your personal context, and making smarter choices based on physiology, not peer pressure or falling for the latest health trend and assuming it’s healthy because someone says it is.
So yes, I held my book today. But more importantly, I used it today to achieve a moment of clarity—I wanted to use it to navigate a new health trend: cast-iron skillets!
I hope you found this helpful. Please share any comments or feedback, and I hope to see you all at the book launch party coming up in May. Stay tuned!
In good health,
Dr Alice
A little more about Dr. Alice Burron and Strategic Action Health:
Dr. Burron is a co-founder of Strategic Action Health, dedicated to helping organizations help their employees make better health decisions. Come check us out here!
Catch us on Instagram: @the.health.navigator and @dr_burron
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Health Shift: Your Strategic Guide to Making Strategic Health Decisions book will officially launch on May 17, 2025! Mark your calendars! And if you’re in Cheyenne, join us for our party at Blacktooth Brewery. Have a beer on us! More information is coming soon.