The claim that sunglasses cause cancer isn’t backed by evidence

Several Facebook posts are sharing a video we have written about before, which claims that wearing sunglasses makes you more likely to develop cancer.

There’s no evidence for this. As we said last time, 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 the video says

The video in this Facebook post shows an extract from an interview with Andreas Moritz, a “medical intuitive” and Ayurveda practitioner who reportedly died in 2012.

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 the 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”.

Why it’s wrong

As our previous fact check explains in more detail, the UV rays in sunlight, and especially the sunburn they can cause, raise people’s risk of skin cancer.

Melanin, a natural pigment that tans the skin in response to sunlight, is produced locally in cells called melanocytes, which is why people develop tan marks where they’ve had contact with the sun beside other areas that were covered up.

A tan from the melanin in your skin does not completely protect it from the sun’s harmful effects, however. A so-called “base tan” is estimated to be the equivalent of wearing sunscreen with a sun protection factor (SPF) of about 3 or 4—far below the SPF30 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.

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.

Gus Gazzard, a professor in ophthalmology and Director of Surgery at Moorfields Eye Hospital in London, previously told Full Fact: “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, also previously 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.

Full Fact has approached the accounts posting this video for comment.