What provides a tan and protects against ultraviolet radiation?

The substance that provides a tan and protects the skin against ultraviolet (UV) radiation is melanin. When the skin is exposed to UV rays, melanocytes (the cells in the skin responsible for producing melanin) increase production, leading to a darker skin tone or tan. This pigmentation acts as a natural barrier, absorbing UV radiation and thereby reducing the risk of DNA damage to skin cells that can lead to skin cancer.

While collagen is important for skin structure and elasticity, and carotene can contribute to skin color through diet, neither directly functions to tan the skin or protect against UV radiation like melanin does. Tyrosine, an amino acid, is a precursor to melanin synthesis but does not provide pigmentation itself. Therefore, melanin is the key component that offers both the cosmetic benefit of a tan and protective properties against harmful UV rays.