Are metal containers a safe alternative for your supplements?
At first glance, they may seem durable, hygienic, and elegant. But when it comes to chemical safety and prolonged contact with capsules, tablets, or powders, metals pose risks worth knowing about.
In this post, we explain what you should keep in mind if a supplement comes in a can or metal container.
🧲 What metals are used in packaging?
The most common in food packaging are:
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Aluminum (light and shiny, used in cans or tubes).
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Tinplate or coated steel (on some metal cans or lids).
None of these materials are used directly without internal protection , as they can react with the product or release particles. Therefore, they all require internal varnishes or plastic coatings to act as a barrier.
⚠️ Potential risks of metal in contact with supplements
1. Migration of metals (such as aluminum)
Although the supplement is not acidic like a food, prolonged contact with uncoated aluminum or tin can cause particle migration into the contents.
Some studies have detected higher than permitted levels of aluminum when the coating is damaged or missing.
➡️ PET poses no risk of metal migration because it does not contain any metals.
2. Dependence on interior varnishes
For a metal container to be safe, it needs an internal lining (usually a plastic resin) that prevents direct contact between the metal and the contents .
This is where new questions arise:
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What does that varnish contain?
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Does it contain BPA residue or other legacy monomers?
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Will it degrade over time?
Although European regulations prohibit the use of BPA starting in 2024, not all countries or imported products yet meet this standard.
➡️ PET doesn't need this type of coating. It's safe in and of itself.
3. Presence of old plastic or gaskets on metal lids
Even if the metal container appears sturdy, it often has a lid with plastic components (such as PVC gaskets or sealing discs) that may contain phthalates if they're older generations. Even lids with a pull-and-open ring can release small amounts of aluminum from the edges when the seal is broken.
Sevens PET does not require soft inner seals . The entire package is manufactured to modern food standards.
And from an environmental point of view…
Metal has a great advantage: its recyclability. But it also has:
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It requires large amounts of energy for its primary production .
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If the inner varnish is damaged, the packaging cannot be recycled as food , but as industrial scrap.
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It has a greater energy impact than PET in transport, due to its weight.
So… metal or PET?
While metal containers can be safe if well designed and compliant, they rely on additional critical components and steps to prevent substance migration.
The PET:
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Contains no metals .
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No coatings required .
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It does not depend on sealing gaskets with phthalates .
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It is lighter and emits less CO₂ during transport.
That's why at Sevens Nutrition, we trust in PET as a more controlled, safer option that's consistent with our commitment to your health and the environment.
🔜 Next post: What are microplastics, BPA, and phthalates?
There's a lot of talk about these compounds. But do you really know what they are, how they're generated, and why we avoid them in Sevens? In the next article in this series, we'll explain everything in detail.