7 Foods You Should Never Cook in Aluminum Foil, According to a Registered Dietitian

1. Anything You're Microwaving

Never mix aluminum foil with the microwave, as it can lead to sparks and even fires, potentially damaging the microwave oven. Avoid storing leftovers in aluminum foil since it isn't airtight. It's a good idea to store them in a microwave-safe container made of glass, which can easily be reheated directly in the microwave.

2. Avoid cooking with Tomatoes, Citrus, and Acidic Marinades

Tomatoes, citrus fruits, and vinegar-based marinades fall under acidic foods and should not be cooked in aluminum foil. According to Wood, “Acidic foods can cause more aluminum to leach into your meal, increasing your aluminum intake, which can potentially lead to issues if consumed over time in large amounts.”

3. Avoid Salty Dishes

Just like acidic foods, salt can cause aluminum to leach into dishes. Any food high in salt, such as homemade savory baked goods or cured meats like ham and sausages, should not be cooked with aluminum to avoid a reaction between sodium chloride (salt) and aluminum ions.

4. Slow-Roasted Dishes

Thinking of wrapping your ribs in foil for hours of slow cooking? You might want to reconsider. “Avoid using foil for long-baked dishes like slow-roasted meats or casseroles,” says Wood. “This can cause more aluminum to be released into your food.” If you're used to slow-roasting in foil, consider switching to ceramic or glass cookware, or using parchment paper between the aluminum and your meal to prevent direct contact.

A study in the International Journal of Environmental Research and Public Health revealed that food cooked in oven-safe cookware had significantly lower levels of aluminum compared to food cooked in aluminum foil. This proves that aluminum leached into the food when using foil.  

5. Foods Exposed to High Heat

While aluminum generally melts at over 1,000 degrees Fahrenheit, it is advisable to avoid using it when cooking foods at temperatures exceeding 400 degrees. Above this point, aluminum may leach into the food. Instead of wrapping your baked potato in foil, try lightly coating it with neutral cooking oil or using parchment paper. The same goes for cooking over an open flame in a campfire—avoid wrapping foods in foil when cooking with direct heat.   

6. Seafood

Seafood packets are a common method for easily preparing fish, but a study published in Food Science and Nutrition indicates that aluminum foil can seep deeper into fish compared to meats from mammals or birds. As a result, fish might be one of the worst proteins to cook in foil. A similar alternative for steaming fillets is cooking fish in parchment paper or using the en papillote technique.  

7. Cookies

While cookies generally bake quickly at lower temperatures and could technically be baked on aluminum foil without much risk, the results might not be ideal. The foil tends to make the bottoms of the cookies overly hard and crispy, and they may stick to the material, causing them to break apart when trying to remove them.