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Warning: Cooking with Aluminum Foil is Toxic

Aluminum foil is super convenient in the kitchen.

You can wrap up foil packets of marinated veggies for the grill, line a baking sheet with foil to cut down on clean up, or cover casseroles in the oven. And don’t forget about storing leftovers in foil!

Most of us don’t think twice about cooking with aluminum foil, but what I’ve uncovered in my research oughta give you pause.

Warning: Cooking with Aluminum Foil is Toxic

The primary issue with aluminum foil is that it can leach aluminum into the food it’s cooked with.

And not just tiny amounts.

A number of studies have looked at aluminum content of foods cooked with aluminum foil, aluminum cookware, and aluminum utensils (even at storing food in aluminum containers), and all of the above can cause aluminum to leach into your food.

Below are some research highlights showing how cooking with aluminum foil is toxic.

Grilled and Baked Fish

How many fish recipes have you read that tell you to wrap the fish in a neat and tidy foil packet? Chefs love it because the flavors infuse into the fish and the foil locks in moisture and gently steams the fillets.

But is cooking in foil packets safe?

One study looked at baked and grilled fish fillets that were wrapped in aluminum foil during cooking and found aluminum concentrations rose by a factor of 2 to 68. (Food Chemistry, 2001)

“All results clearly showed that some aluminium migrated from the aluminium foil into the food.” (Food Chemistry, 2001)

A DOUBLING of aluminum is scary, no doubt, but 68x more? Yikes!

What accounted for the difference?

In this study, grilled fish fillets accumulated more aluminum compared to the baked fish, likely due to higher heat exposure. Also, the longer the fish was in contact with aluminum foil, the more aluminum accumulated.

Acidic ingredients also upped the amount of aluminum that leached into the fish.

So, that grilled salmon recipe that calls for lemon juice? Best to skip the foil packet on that one and choose another cooking method! (psst – Keep reading for safer alternatives to aluminum foil.)

Ground Meat

“Cut down on clean-up by lining your baking sheets with aluminum foil,” they say. But “they” might rethink this advice after reading the following study.

In a 2012 study, the concentration of aluminum was measured in ground meat before and after cooking in aluminum foil.

They tested 6 different “food solutions” (gotta love the not-so-mouth-watering research jargon) containing ingredients such as tomato juice, citric acid, apple vinegar, salt, and spices to see if it affected how much aluminum leached into the food.

Aluminum leaching was found to be highest in acidic solutions (in other words, recipes that contained vinegar, tomato juice or citric acid). (Int. J. Electrochem. Sci., 2012)

That means it’s wise to skip aluminum foil baking pans to make lasagna, meatloaf (coated in tomato sauce), or for cooking marinated meat.

Most alarming, though, was the fact that aluminum levels exceeded recommended upper intakes set by the World Health Organization (WHO) in some samples.

As the researchers put it:

The results clearly indicate that the use of aluminum foil for cooking contributes significantly to the daily intake of aluminum through the cooked foods. According to the World Health Organization (WHO), the obtained values are considered to be unacceptable.” (Int. J. Electrochem. Sci., 2012)

Vegetables

Meat and fish are not the only foods prone to accumulating aluminum when cooked in foil or aluminum cooking vessels.

In one study, vegetable extracts were cooked in an aluminum pot and tested for aluminum residues. Six different vegetables were prepared: tomato, onion, potato, green bean, carrots and zucchini. (Int. J. Electrochem. Sci., 2012)

Aluminum leached into every vegetable extract tested, but varied by the type of vegetable, temperature, cooking time, and presence of salt.

Tomatoes accumulated the most aluminum, likely because they are acidic. (For what it’s worth, potatoes accumulated the least).

Consider this food for thought if you line your baking sheets with foil when roasting vegetables, especially acidic veggies, like tomatoes.

Aluminum leaching from cookware isn’t something to take lightly. It can add “large doses” of aluminum into the diet:

“Comparing the present results with the Provisional Tolerable Weekly Intake of aluminum approved by the FDA/WHO of 1mg/kg body weight per week showed that aluminum leaching from aluminum cookwares in some vegetable extracts may add large doses of aluminum into the diet.” (Int. J. Electrochem. Sci., 2012)

Other Foods

A number of other foods have been tested for aluminum leaching – from foil, cooking vessels, cooking utensils, and even storage in aluminum containers.

I only highlighted a few foods in this post, but everything from lamb, chicken, fish, milk, lentils, tea, and even leafy greens are known to accumulate aluminum when either cooked or stored in contact with aluminum. (Journal of Saudi Chemical Society, 2010; Food Chemistry, 2000; Biological Trace Element Research, 2000)

But maybe you’re not convinced that aluminum is anything to worry about…

Why should we be concerned about cooking with aluminum foil and aluminum leaching into food?

Simply put, aluminum is a toxic metal with no known beneficial effects in the human body.

It preferentially accumulates in the brain and has been linked to neurological problems. (Environmental Research, 2002)

Some research has found high aluminum exposure correlates with the development of Alzheimer’s disease. (J Alzheimers Dis, 2011)

“The hypothesis that aluminum significantly contributes to Alzheimer’s disease is built upon very solid experimental evidence and should not be dismissed. Immediate steps should be taken to lessen human exposure to aluminum, which may be the single most aggravating and avoidable factor related to Alzheimer’s disease.” (J Alzheimers Dis, 2011)

Pregnant women and developing babies are especially vulnerable to aluminum exposure. (I consider it one of the 5 reasons to avoid soy in pregnancy.)

Aluminum can also interfere with normal mineral metabolism in the body, contributing to a specific type of bone softening called aluminum-induced osteomalacia.

The takeaway here: you don’t need aluminum in your body, nor do you want it there.

Whatever you can do to minimize your exposure, the better.

That means finding alternatives to aluminum foil, so you’re not accumulating toxic levels in your body.

Alternatives to Aluminum Foil

If you use aluminum foil to line baking sheets, consider using parchment paper instead. I prefer this brand of unbleached parchment paper. (I often skip lining pans entirely and just use some elbow grease to wash baking pans. Just ensure your metal baking pans are NOT made of aluminum!)

When covering food in the oven (or stovetop), you can try pans that have a lid (like a lidded casserole) or cooking in a dutch oven.

Sometimes, though, you really need the flexibility and non-flammable properties of foil (like when you need to cover a turkey). In that case, I recommend using a layer of parchment paper directly over the food and a layer of foil on top of that. The foil will keep the parchment in place and the parchment will keep the aluminum from actually touching the surface of the food. I use this same method when covering casseroles, like my Low-Carb Lasagne with Zucchini Noodles.

For grilling, consider stainless steel grill pans for vegetables (like this one) or doing the parchment-aluminum foil trick in lieu of straight up foil packets like I described above. (You can cook things “en papillote” (meaning wrapped in parchment paper) in the oven, but this would obviously burn on the grill.)

For storing leftovers, opt for glass storage containers, which don’t leach a thing! I like these glass lock containers. Bonus points: these can go from oven-to-fridge, so they cut down on dishes.

Hopefully this post was helpful to you!

Before you go, I’d love to hear your thoughts on cooking with aluminum foil:

Did you know cooking with aluminum foil was toxic?
Will you stop cooking with aluminum foil after reading this?

Until next week,
Lily

PS – If you know a friend or family member who’s always cooking with aluminum foil, they probably aren’t aware of the dangers.  Keep each other healthy and share this post with them!


References

  • Ertl, Kathrin, and Walter Goessler. “Aluminium in foodstuff and the influence of aluminium foil used for food preparation or short time storage.” Food Additives & Contaminants: Part B 11.2 (2018): 153-159.
  • Bassioni, Ghada, et al. “Risk assessment of using aluminum foil in food preparation.” Int. J. Electrochem. Sci 7.5 (2012): 4498-4509.
  • Ranau, R., J. Oehlenschläger, and H. Steinhart. “Aluminium levels of fish fillets baked and grilled in aluminium foil.” Food Chemistry 73.1 (2001): 1-6.
  • Stahl, Thorsten, et al. “Evaluation of human exposure to aluminum from food and food contact materials.” European Food Research and Technology 244.12 (2018): 2077-2084.
  • Dordevic, Dani, et al. “Aluminum contamination of food during culinary preparation: Case study with aluminum foil and consumers’ preferences.” Food science & nutrition (2019).
  • Cammaerts, M. C., and R. Cammaerts. “Is Metal Leakage from Aluminum Foil without Adverse Effects? A Study on Ants as Models.” J Nutr Health Sci 5.1 (2018): 103.
  • Al Juhaiman, Layla A. “Estimating aluminum leaching from aluminum cookware in different vegetable extracts.” International Journal of Electrochemical Science 7.8 (2012): 7283-7294.
  • Bamji, M. S., and M. Kaladhar. “Risk of increased aluminium burden in the Indian population: contribution from aluminium cookware.” Food Chemistry 70.1 (2000): 57-61.
  • Al Juhaiman, Layla A. “Estimating Aluminum leaching from Aluminum cook wares in different meat extracts and milk.” Journal of Saudi Chemical Society 14.1 (2010): 131-137.
  • Semwal, Anil D., et al. “Leaching of aluminium from utensils during cooking of food.” Journal of the Science of Food and Agriculture 86.14 (2006): 2425-2430.
  • Al Zubaidy, Essam AH, Fathia S. Mohammad, and Ghada Bassioni. “Effect of pH, salinity and temperature on aluminum cookware leaching during food preparation.” International Journal of Electrochemical Science 6.12 (2011): 6424-6441.
  • Veríssimo, Marta IS, Joao ABP Oliveira, and M. Teresa SR Gomes. “Leaching of aluminium from cooking pans and food containers.” Sensors and Actuators B: Chemical 118.1-2 (2006): 192-197.
  • Bichu, Shrirang, et al. “Relationship between the Use of Aluminum Utensils for Cooking Meals and Chronic Aluminum Toxicity in Patients on Maintenance Hemodialysis: A Case Control Study.” Journal of The Association of Physicians of India 67 (2019): 52.
  • Tietz, Thomas, et al. “Aggregated aluminium exposure: risk assessment for the general population.” Archives of toxicology (2019): 1-19.

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Lily Nichols is a Registered Dietitian/Nutritionist, Certified Diabetes Educator, researcher, and author with a passion for evidence-based prenatal nutrition and exercise. Her work is known for being research-focused, thorough, and unapologetically critical of outdated dietary guidelines. She is the author of two bestselling books, Real Food for Pregnancy and Real Food for Gestational Diabetes.

37 Comments

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  1. Hey! I have a coated Dutch oven that is aluminum… would that be the same thing? Or since technically no metals touch it would be fine?

    • Hi Christina,
      Assuming there are no scratches (meaning the enamel is in very good shape), you’re probably fine.

      A dutch oven made of aluminum is surprising, though, given that aluminum does a pretty poor job of maintaining heat. Most are made of cast iron. You might check with the manufacturer to see if it’s indeed made of aluminum.

  2. Wow — thanks for posting this. I had not thought about this as a source of dietary aluminum and plan to be way more careful when and where I use foil in the kitchen.

  3. Great post. I stopped wrapping my food in foil to cook a few years ago, but still do line some pans with it, especially when cooking in my toaster oven, and cover pies and roasts. I will definitely avoid that and start using parchment paper.

    • I use the parchment + foil trick quite often for covering roasts. 😉

  4. This is just the post I needed to share with our readers – I am big fan of parchment paper too- the unbleached pre-cut sheets are so great. Thanks for the well -written and well-researched post, Lily!

    • Thanks Jessica! I always appreciate that you and Stacey steer clear of foil in your recipes.

  5. I always avoid aluminium when cooking but must admit to sometimes using tinned foods (fish, coconut milk, chickpeas) – these are going to have to go too!

  6. Ugh. Yes I knew aluminum wasn’t good, so I’ve been using it minimally. I’ll probably just have to stop all together now. What disturbs me the most is how many times I wrapped a sweet potato in it and then fed it to my daughter when she was a baby! Uggghgg!

    • Don’t sweat the past. All we can control are our future choices and your daughter is lucky to have such a mindful mama.

  7. Had no idea, thanks so much for this valuable info! Just bought the parchment paper you recommended and am sharing this article!

    • You bet, Lana. Thanks for sharing!

  8. Had no idea! Thank you for this post . I will definitely use your parchment foil trick.

  9. I usually cover my pan in foil before baking bacon, I had no idea I was making the bacon so toxic! Would layering foil and then parchment make it safe?

    • I suppose if the parchment paper is larger than the foil (meaning no bacon or bacon grease is in contact with foil), you’d be safe.

  10. I always had oven linning by aluminum foil. Would that release toxins into my food?

    • Everything that I’ve read suggests foil needs to be in contact with the food to leach aluminum.

  11. Did you run across any research about aluminum levels in drinks in aluminum cans?

    • I’d love to know about this, too! I have sparkling water in aluminum cans daily… eek!

  12. I was wondering the same thing, I don’t use too much in the kitchen but I do drink out of cans every day.

  13. I had heard this before and so I minimize my use of foil. I’ve done the foil over parchment thing when storing food as well (like when I make my husband a sandwich for his lunch on a baguette that won’t fit in a baggie). One question – what’s the max temp on unbleached parchment? I usually use Reynolds and you can’t use it in an oven higher than 425.

    • That’s a good question. I’m not sure of the max temp for parchment paper.

  14. can you provide actual references so we can read them? all i see are the abbreviated in-text citations.

  15. Lily – what do you recommend as an alternative to aluminum cookie sheets – everything I’m finding seems to be made of Aluminum

  16. were can i buy parchment paper

    • Grocery stores, kitchen/baking stores, or Amazon.

  17. I see what your saying about how aluminum is bad but when you were talking about it being correlated with Alzheimer’s. Correlation does not mean causation. It hasn’t been scientifically proven.

  18. Because I have to have gluten free toast, but my husband doesn’t, I line the rack to toast my GF bread. Otherwise I would have to wash the rack every time. Is my toast toxic? If I use parchment paper instead, how do I keep it flat? I have been using the aluminum foil for a long time. Thanks!

    • In my opinion, the risk:benefit here of gluten contamination outweighs the aluminum in this situation. I doubt there’s a significant transfer of aluminum to the toast considering it’s dry, non-acidic, and compared to other foods (like chicken breast or fish, for example), has low surface contact to the foil.

  19. What about aluminized steel cookie sheets? Would those be considered toxic?

  20. Great Thoughtful and thorough. Human reasoning can connect the dots that Aluminum is poison to the human body in amounts that are not naturally derived thru food and water and that Aluminum has serious side effects to the living organism.
    Aluminum is a significant part of the modern world and its ill effects are condemning.
    We as a species are doing our own selves in, and future generations will not thank us for poisoning the planet in the quest for progress and whatever that means…wrecking this planet and attempting to leave for another which is madness in itself- colonization.
    Love one another by taking care of planet earth.
    Wisdom is expensive.

  21. Excellent article, I can’t wait to repost for our nutrition clients.
    What do you think about Silpat sheets?

  22. Is using foil to line your racks to keep them clean considered as harmful as cooking with it touching your food. Do the chemicals release into your food that way?

  23. Great article. Here’s a slightly different question: I have a new toaster oven with a non-stick drip tray (another potential toxin) that doesn’t touch the food. However, if I wrap it in aluminum foil, does that prevent the teflon (or related chemical) particles from contaminating food? I have to prevent the teflon/aluminum double whammy!

    • That’s a good question. I’m not sure.

      With aluminum, it only transfers to food if it’s in direct contact. With non-stick chemicals, some are airborne and can be breathed in if the surfaces reach a high temperature. You might like this article on non-stick cookware for more info on that topic. https://lilynicholsrdn.com/non-stick-pans-pregnancy/

  24. Butcher paper is another option to consider because it’s raw paper, whereas parchment paper has a silicone (aka plastic) lining to make it non-stick—yes, even the “natural” parchment papers are lined.

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