An Instagram post liked almost 10,000 times claims that sunglasses increase the likelihood of getting sunburned. This is false.
The post caption says: “[Sunglasses] trick the brain into thinking that it’s dark due to their dark lens. This leads to a reduction in the production of melanin which is essential for vitamin D synthesis. Wearing sunglasses therefore increases your risk of low vitamin D and sunburn.”
As we will explain, the idea that melanin leads to vitamin D synthesis which then protects against sunburn is wrong at every step.
Honesty in public debate matters
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Melanin is a pigment that affects the colour of your skin, hair and eyes. It protects skin cells against DNA damage caused by UV rays from the sun.
Melanin is produced by cells called melanocytes which sit in the deeper layers of the skin. Melanocytes are stimulated by the sun’s UV rays to produce melanin, although there are other processes that can affect how much is produced (for example pregnancy or hormone dysfunction). The melanin is produced by cells that have been damaged by UV rays, demonstrated when you develop a tan on areas of skin that’s been exposed to the sun.
So melanin production by melanocytes in and around the eyes specifically may be reduced if they are shielded from UV by sunglasses. But sunglasses would not prevent the body from producing melanin in general. Skin exposed to UV will continue to produce melanin.
The use of eye protection by people using sunbeds demonstrates that a tan, and therefore melanin production, can easily be achieved, whether UV reaches the eyes or not.
The post also says that melanin is used in vitamin D synthesis. In fact, it “competes” with cells producing vitamin D, meaning that people with darker skin (as a result of more melanin) generally need more sun exposure than lighter skinned people to make the same amount of the vitamin.
The importance of sunglasses
The caption also says “Sunglasses are not ideal and if you don’t need to wear them, then you probably shouldn’t.”
Exposing your eyes too much to UV rays from sunlight can cause irreversible damage and in some cases blindness. Sunglasses that have been verified to filter out UV rays protect against this and are recommended by the NHS when outside in the sun, especially between March and October.
Bad information about health can cause harm if people make decisions based on it. We have previously written about social media posts that discourage people from using medications or equipment based on false information.
We contacted the account that posted the image via Instagram but have not received a response at time of writing.
Image courtesy of Davner Ribeiro