Before wrapping marinated meat in aluminum foil, know what a study found after baking it at 428°F

If you've ever wrapped salmon, chicken, or a marinated pork chop in foil before baking it, you're doing what most home cooks in the US do without a second thought. But what happens when the oven gets hot? A 2019 study in Food Science & Nutrition by researchers from the University of Veterinary and Pharmaceutical Sciences Brno in the Czech Republic found that aluminum foil does leave measurable amounts of aluminum in food, and how much depends on what you’re cooking and how.

The team tested 11 foods including Atlantic salmon, mackerel, duck breast, cheese, tomato, paprika, Carlsbad dumplings, pork roast, pork neck, chicken breasts, and chicken thighs, each wrapped in five different brands of store-bought foil. All foods were tested both marinated and plain, baked for 40 minutes at 220°C (428°F), a fairly standard home-baking temperature, and then checked using two different lab methods.

Marinade made the biggest difference
The biggest factor in aluminum transfer, the study found, wasn’t the food itself, but whether it had been marinated or not. The highest aluminum increase recorded in the entire study was in marinated duck breast, at 117.26 ± 1.37 mg/kg (dry mass), while the unmarinated duck sample baked in the same foil measured 0.00 mg/kg. Marinated salmon and mackerel had a similar jump, rising to 41.86 mg/kg and 49.34 mg/kg respectively. Overall, marinated salmon and mackerel contained about 20 times more aluminum than unmarinated samples, with some samples showing increases as high as 40 times.


The likely explanation is a chemical reaction. Most of the marinades in the study contained olive oil, salt and acidic ingredients such as lemon juice or tomato. The study found that both salt and acidity increase the rate of corrosion in foil, enabling more metal to leach into the food.

Skin acted like a natural shield
One unexpected finding involved duck skin. According to the study, duck breast baked with the skin on absorbed significantly less aluminum than skinless duck baked in the same manner. Researchers believe proteins in the skin, including collagen, elastin and keratin, help form a barrier that slows aluminum diffusion into the meat.

Should you really be concerned?
The researchers say the risk is low. Aluminum is already present in small amounts in everyday foods such as cereals, vegetables and tea, so the highest readings were described as “not alarming” for a healthy adult eating an occasional foil-baked meal.

Regulators have set reference points for safe exposure to aluminum. In 2008, the European Food Safety Authority established a tolerable weekly intake (TWI) of 1 milligram of aluminum per kilogram of body weight per week, a level considered safe to consume regularly, even over a lifetime. The Agency for Toxic Substances and Disease Registry reports that only a small percentage of ingested aluminum is absorbed in the US, and typical dietary exposure in the US is not a significant concern for those with normal kidney function.

The study's authors said two groups should be treated with extra caution: young children, whose lower body weight means the same amount of aluminum makes up a larger share of their weekly limit, and people with kidney problems, because kidneys usually remove excess aluminum from the body.

This is not an isolated result. Another study titled ‘Aluminum in foodstuff and the influence of aluminum foil used for food preparation or short time storage,’ by researchers Kathrin Ertl and Walter Goessler found that short-term contact between food and aluminum foil does increase aluminum levels in food, but characterized the increase as fairly marginal for most everyday foods, broadly matching what the Brno researchers found.

Most people don't check the label
The team surveyed 784 people about their foil habits. Survey results from the study found 72.9% said they don’t care if they are wrapping acidic or salty foods in foil, while 67.5% said they had never looked into whether aluminum foil could pose a health risk. Just 43.6% said they had heard about the possible dangers of aluminum, which means that more than half had never really thought about it.

Simple swaps that help
You don't need to throw away your foil. Just skip it for acidic or salty marinades. Your recipe calls for lemon, vinegar, tomato, wine, or a lot of salt? Parchment paper or a covered baking dish is a safer bet. If you do use foil with marinated foods, a layer of parchment paper between the food and the foil can help.

The study also suggests watching oven temperature, since other research has linked higher baking temperatures with increased aluminum leaching. Ertl and Goessler's research, cited in the Brno study, also suggests that storage time matters, so it is worth transferring cooled leftovers to a container instead of leaving them wrapped in foil for days.

The takeaway
That does not mean you need to worry about an occasional foil-wrapped chicken dinner. But it is a good reminder that how you cook can be just as important as what you cook. If you’re using lemon, tomato or a salty marinade, a small, easy habit is to reach for parchment paper instead, which can meaningfully cut aluminum exposure, especially if you’re cooking for young kids or someone with a kidney condition.