Debating the Superiority of Pheomelanin versus Eumelanin
In the intricate world of skin pigmentation, two key players stand out: eumelanin and pheomelanin. These pigments, secreted by melanocytes, play significant roles in determining skin colour, protecting against harmful UV radiation, and influencing health outcomes.
Eumelanin, responsible for darker pigmentation, produces brown and black tones in the skin. It is the predominant pigment in people with darker skin types. On the other hand, pheomelanin produces lighter red or yellow pigmentation and is more common in individuals with lighter skin tones, such as redheads.
When it comes to protection against UV radiation, eumelanin acts as an effective natural sunscreen. It absorbs and scatters UV rays, limiting their penetration into skin cells, which reduces DNA damage, sunburn, photoaging, and the risk of skin cancer. Eumelanin also functions as a potent antioxidant by neutralizing reactive oxygen species (ROS) generated by UV exposure, thereby reducing oxidative stress and cellular damage.
Pheomelanin, in contrast, is less protective. Instead of effectively absorbing UV, pheomelanin can undergo photochemical reactions upon UV exposure that generate ROS. This increases oxidative stress, which can lead to damage of DNA, lipids, and proteins in skin cells, potentially accelerating skin aging and increasing susceptibility to UV-induced skin damage and carcinogenesis.
Individuals with higher eumelanin levels generally have greater natural protection against UV-induced skin damage and related health risks, such as skin cancer. Those with higher pheomelanin levels have less UV protection and may even suffer more oxidative stress upon UV exposure, contributing to increased risks of sunburn, photoaging, and skin cancers, particularly melanoma, which is the most aggressive form of skin cancer.
However, melanin's protection is not absolute, so sun protection measures like sunscreen and protective clothing remain necessary for all skin types. Understanding the biological function of skin color can help dispel discrimination based on skin color.
Melanocytes can be found all over the body, and they populate regions near the hair, the iris, and the adrenal glands. People living near the equator zone are more likely to have a high eumelanin content due to increased UV radiation exposure. In contrast, a high pheomelanin content is typical in people who live far from the equator zone, such as northern Europe.
Pheomelanin content is associated with lighter skin tone, and the MC1R gene, present in melanocytes, induces pheomelanin, which can cause red hair. Pheomelanin can accumulate and cause a yellow and red pigment to appear, most pronounced on the lips, nipples, vagina, and penis. Unlike eumelanin, pheomelanin does not effectively protect from the harmful effects of UV radiation.
In summary, eumelanin and pheomelanin play distinct roles in skin pigmentation, UV protection, and health implications. Eumelanin provides strong UV protection, while pheomelanin can generate ROS upon UV exposure, increasing oxidative damage. Individuals with higher eumelanin levels have a lower risk of UV-related skin damage and skin cancer, while those with higher pheomelanin levels have a higher susceptibility to UV-induced damage and skin cancer. Daily sun protection remains essential, regardless of skin tone.
Health science underscores the role of melanin, specifically eumelanin, in protecting the skin against harmful UV radiation and reducing the risk of skin cancer. On the contrary, pheomelanin, though associated with lighter skin tones, can generate reactive oxygen species upon UV exposure and increase oxidative stress, potentially leading to DNA damage and a higher susceptibility to skin cancer. Health-and-wellness practices like sunscreen and skin-care products with antioxidants can further bolster UV protection for all skin types.
