Copper on your skin: what has actually been measured

The only copper that stays there all day

You drink from a copper bottle a few times a day. A bracelet sits against the same patch of skin for twenty-four hours. That makes it the only use where skin and metal stay in unbroken contact, and it is also the use that has collected the most stories. What follows is what has really been measured, with the source alongside it.

In short

• Copper demonstrably passes through the outer layer of skin: in an in-vivo study it was recovered from the deeper layers of the stratum corneum.
• That study was set up with exactly this question in mind: what does a copper bracelet do on the skin?
• Copper is a building block for your skin itself. Lysyl oxidase, the enzyme that ties collagen and elastin together, only works with copper.
• The copper tripeptide GHK-Cu, which your body makes itself, stimulates collagen and elastin; the level drops from around 200 to 80 nanograms per millilitre between the ages of twenty and sixty.
• Two of the eight officially approved EU claims are about this: normal connective tissue and normal skin pigmentation.
• In a double-blind, placebo-controlled trial with copper-containing fabric, a measurable difference in the skin showed up after two and after four weeks.
• Wound dressings with copper oxide are FDA-cleared and bring microbes down by a factor of ten thousand within three hours in the lab.

Does copper get through the skin?

This has been studied, and the answer is yes. Jurij Hostýnek and Howard Maibach, dermatologists at the University of California in San Francisco, applied copper as a powder to the forearms of healthy volunteers and left it there for up to 72 hours. They then stripped the stratum corneum twenty times in a row with adhesive tape and measured each strip by mass spectrometry, at a detection limit of 0.5 parts per billion. Untreated skin was measured the same way for comparison.

The copper turned out to distribute itself through the successive layers of the stratum corneum. The researchers name, in so many words, the question of whether wearing copper bracelets does anything for people with inflammatory complaints as the reason for their study: this is not a side note but the actual subject.

How much a bracelet gives off in practice has been measured too: in the oldest clinical bracelet study it came to an average of thirteen milligrams of copper a month. That background is in the copper bracelet: a centuries-old tradition.

What copper does inside the skin

Quite apart from what goes in from the outside, there is copper in your skin because your skin needs it. Collagen and elastin, the two proteins that give your skin firmness and spring, only become a network once they are tied to one another. The enzyme that ties those knots is called lysyl oxidase, and it is a cuproenzyme: without copper at the heart of it, nothing happens.

There is another copper compound your body makes itself. In 1973 Loren Pickart isolated a tripeptide from human blood plasma that binds copper strongly: GHK-Cu. At twenty there is around 200 nanograms per millilitre of it in your plasma; at sixty, 80. Research on this molecule describes it stimulating collagen, elastin and glycosaminoglycans and speeding up wound healing. It has become a standard ingredient in serious skincare, and it only does that work with the copper atom in place.

That is exactly why two skin-related claims appear on the European list of approved health claims for copper: copper contributes to the maintenance of normal connective tissue, and copper contributes to normal skin pigmentation. All eight are in the eight official EU claims.

Copper against the skin, measured double-blind

The best measurement of copper in contact with skin comes not from a bracelet but from fabric. In a double-blind, placebo-controlled, randomised trial, 57 volunteers between 40 and 60 slept for four weeks on a pillowcase with copper oxide in it, or on an identical-looking case without copper. Nobody knew which.

After two and after four weeks the copper cases showed a difference that held up statistically, with a p-value below 0.001 for wrinkle depth as well as for fine lines and overall appearance. The trial was published in 2009 in the International Journal of Cosmetic Science. It concerns fabric rather than solid copper, but it is the cleanest evidence there is that skin does something with copper it rests against.

Wound care goes a step further still. Wound dressings with copper oxide are cleared by the US FDA for acute and chronic wounds, and in laboratory tests they bring bacteria, fungi and viruses down by a factor of ten thousand within three hours. They have been in use in healthcare for over six years, good for 3.4 million patient days. That is not a bracelet, but it does show what copper does when it lies against skin all day.

Where the tradition begins

Alongside that measured part sits an older way of looking at it, and it is worth naming, because it is how a lot of people arrive at copper in the first place. In that tradition the body itself is electrical, which on its own is true: an ECG measures nothing other than the electrical activity of a muscle, and a nerve impulse is literally a wave of voltage. Copper is the metal an electrician uses to connect a building to the earth, and that image, direct contact with the earth through a conductor, is what the earthing or grounding tradition rests on.

Research has been done on that as well. The review by Chevalier and colleagues in the Journal of Environmental and Public Health from 2012 gathers what had been published on it up to then. It is a live and contested field, and we attach no health claims to it. What it does explain is why copper in particular is the metal of choice in this corner: the same conduction that all of electrical engineering runs on. How that works physically is in why copper conducts.

What makes the contact good

If you want copper against your skin, then copper has to be against your skin. A copper-plated bracelet with a coat of lacquer gives off nothing and starts flaking after a few months; solid, uncoated copper does what it does because there is nothing in between. Watch out for nickel as well: it is the most common cause of contact allergy in jewellery, and our bracelets contain none. How to recognise real copper is in the complete buying guide.

The faint green mark you see on your skin after a while is a reaction between copper, sweat and skin oils, and it rinses off with water. It is also the most visible proof that you are dealing with pure copper: why copper turns green or black.

Have a look at the copper bracelet in four finishes, or browse the full range.