Brown spots form as a result of melanin accumulation in the skin. This dark brown pigment is an essential component that plays a protective role against UV rays. Melanin production is triggered by exposure to sunlight. UV rays indeed act on tyrosine, an amino acid, and, thanks to the enzyme tyrosinase, trigger a cascade of reactions leading to the synthesis of melanin. This process is melanogenesis.
Brown spots gradually form throughout life, as exposure to the sun is repeated. Their shape and size vary. Brown spots are primarily located on the most sensitive and exposed parts of the body, such as the face, neck, shoulders, arms, and legs. They frequently appear around the age of forty, but can also emerge earlier.
Although the sun plays a major role in the development of brown spots, other factors can also contribute to this phenomenon. Indeed, tobacco, pollution, or an unbalanced diet can lead to a oxidative stress in the body's cells, that is, the production of free radicals. These reactive oxygen species then cause damage to the DNA and accelerate skin aging.
Finally, the melasma is a type of brown spot directly related to a hormonal change. During pregnancy, the level of estrogen in the body significantly increases, which induces an overproduction of melanin.