No, there’s no evidence sunglasses cause cancer

We’ve seen another widely shared post on Instagram, from an account with over 700,000 followers, making claims about sunglasses supposedly causing cancer.

As we’ve said before, and more recently in a fact check in April, there is no credible evidence to support these claims. Verified sunglasses protect your eyes and the skin around them by filtering out the harmful cancer-causing UV rays from sunlight, and their use is widely recommended, including by the NHS.

What’s been claimed

The latest video we’ve looked at, which was posted in April and now has over 130,000 likes, appears to be some edited extracts from a longer interview with Andreas Moritz, a “medical intuitive” and Ayurveda practitioner who reportedly died in 2012. The video was also posted on TikTok in May.

In the Instagram video, Mr Moritz says: “When they first introduced sunglasses, it started triggering a massive increase of cancers… It has everything to do with cancer.”

Later on, he says: “You have to allow UV light to come in. When you do that you are producing a hormone in the brain that is responsible for the melanin production in your skin. So that’s where your skin protection occurs. If you are not producing that, your skin becomes susceptible to even sunlight.

“Say you wear sunshades, your body thinks it’s dark outside. It doesn’t make that hormone that is responsible for producing melanin to protect your skin.”

Mr Moritz seems to be claiming here that the body effectively protects itself from the risk of sun-caused skin cancer by producing melanin, which tans the skin—and that it is unable to produce a hormone responsible for the production of this melanin if UV light is blocked by sunglasses, thereby raising the risk of cancer.

But there is no credible evidence to support this claim, which a leading eye doctor told Full Fact has “no scientific basis”.

The role of melanin

As we said before, the UV rays in sunlight, and especially the sunburn they can cause, do raise people’s risk of skin cancer. Indeed, Cancer Research UK says that nine out of 10 cases of melanoma—the most serious type of skin cancer—could be prevented if people stayed safe in the sun and avoided sunbeds.

Melanin is a pigment that is produced locally in cells called melanocytes that sit in the skin’s deeper layers. This is why people can develop tans on the parts of their skin that were exposed to the sun, but not on the areas that were covered up. Melanocytes are stimulated by the sun’s UV rays, but other things such as pregnancy or hormone dysfunction can affect how much melanin is produced.

A tan from the melanin in your skin does not completely protect it from the sun’s harmful effects. A so-called “base tan” is estimated to be the equivalent of wearing sunscreen with a protection factor of about 3 or 4—far below the 30 or more provided by most recommended sunscreens, or by covering up or staying in the shade. And of course the skin lacks even this protection while the tan is being achieved.

How do sunglasses affect your protection from the sun?

Sunglasses verified to filter out UV rays can protect your eyes and the skin immediately around them, and they are recommended by the NHS. But there is no good evidence that they will have any effect on the protection of your skin everywhere else. You can check whether a pair of sunglasses will filter out harmful UV by looking for the appropriate mark.

Mr Moritz refers to a “hormone”, which he claims is stimulated by light through the eyes and has a role in producing melanin. It’s not clear which hormone he is referring to. There is limited evidence that mice whose eyes were irradiated with UVB light may produce more melanocyte-stimulating hormone (MSH), which regulates melanin production, but this is not good evidence that sunglasses significantly affect human melanin production or skin protection.

Full Fact spoke to Gus Gazzard, a professor in ophthalmology and Director of Surgery at Moorfields Eye Hospital in London. He told us: “Any link between sunglasses and increased risk of cancer is purely hypothetical and speculative, with many unproven steps within that link. UV eye protection is recommended because of the protective effect that it has for the eye itself.

“The argument here, that sunglasses cause cancer by reducing tanning all over the body, makes no sense, and has no scientific basis…. Melanin production can be stimulated locally within the skin, as we all know from local sun tanning, which doesn't require ophthalmic stimulation, and people who lose vision can still get tanned.”

Dr Rubeta Matin, a consultant dermatologist and senior clinical lecturer in dermatology in Oxford, told us that there was no good evidence that wearing sunglasses raises the risk of skin cancer by reducing the UV light that enters the eye in the manner described in this video.

She confirmed that UV light on the skin “does increase levels of MSH which leads to increased melanin production which causes tanning which is protective against skin cancer”, but noted that this has only a limited effect in fair-skinned people.

She also told us that there is evidence that UV light contributes to the risk of developing ocular melanoma (a form of cancer in the eyes), which means that wearing sunglasses can reduce that proven risk.

The account that shared this video on Instagram is called The Conscious Awakening. Full Fact has contacted them to explain the reasons for our fact check and to ask if they wanted to comment, but we have not heard back.