Why do some people get suntanned and others don't?

In summer, we have more outdoor activities and expose ourselves much more to the sun. That’s why you should use sunscreen, especially at this time of year. However, even using sunscreen properly is not enough to stop some people's skin turning red after the slightest exposure to the sun, while others will get a tan. Why this difference? Dr Susana Puig, head of the Dermatology Service at the Clínic Barcelona, explains:

This happens because “Each of us produces a different quantity and quality of melanin. Melanin is a pigment produced by our cells found in the basal layer of the skin,” explains Dr Puig. The cells that produce melanin are called melanocytes. This pigment or melanin produced is transferred to keratinocytes, the cells that make up the entire outer layer of the skin, which flakes off every 21 days. “The melanin covers the keratinocyte nuclei like an umbrella” adds Dr Puig. By forming this kind of protective layer, the melanin pigment prevents the sun's rays from damaging skin cells and causing burns or diseases like skin cancer.

The difference is in the quality  

Everyone produces two fundamental types of melanin. The first one is eumelanin, or “good” melanin, and the other is called pheomelanin or “bad” melanin. Pheomelanin is orange-red in colour. Eumelanin, on the other hand, is dark brown or black.  

The ratio between these two types of pigment is what makes the difference in each person's ability to tan. The skin of people with a higher amount of eumelanin will darken faster when exposed to the sun and so they will be more protected from burns.  

In Spain, 70-80% of the population have a similar proportion of eumelanin and pheomelanin. Although, Dr Puig adds, “5% of the population produces pheomelanin only. Can you imagine who these are? Exactly, redheads." Red-haired people have pheomelanin only, and cannot produce “good” melanin. Pheomelanin is not photoprotective, while it also increases so-called oxidative stress in the cell. This is the damage that occurs in the cell caused by ultraviolet radiation.  

Therefore, what will determine whether a person can tan or simply turn red is both the amount of melanin produced by their skin cells and its quality. Or, the ratio between “good and bad” melanin. However, it’s a good idea for everyone to protect themselves from the sun at its hottest, by wearing sunscreen, t-shirts and hats. Even a tanned person is still vulnerable to damage from the sun's rays, especially long term.