Chinese people value fair skin as an ideal of beauty, but as a member of the yellow race, skin can darken easily with insufficient care, affecting one's appearance and causing distress for many. How does skin darken?
1. Melanin Production and Metabolism
Melanin is the most crucial substance determining skin tone, biochemically classified as a high-molecular-weight protein with a polyquinone structure.Melanin formation involves a complex series of metabolic processes. Primarily, tyrosine is gradually converted into dopa under the action of tyrosinase. Dopa is then accelerated into dopaquinone by tyrosinase, subsequently evolving into colorless substances—dopachrome——dihydroxyindole—quinone-type indole, ultimately forming melanin. This synthesis requires the participation of enzymes, copper, zinc, iron, multiple amino acids, pantothenic acid, folic acid, vitamin B12, para-aminobenzoic acid, and ultraviolet light. Disruption at any stage can impair melanin formation.
2. Causes
Skin darkening arises from multiple factors, primarily including genetic predisposition, endocrine disorders, and melanin synthesis abnormalities. It is also associated with occupational exposure, environmental conditions, light exposure, and certain medications.
3. Prevention and Treatment
(1) Protection: Avoid direct sun exposure. Maintain a balanced diet rich in fresh vegetables, fruits, hawthorn berries, carrots, etc., while minimizing intake of irritating foods to reduce melanin production.
(2) Avoid estrogen-containing preparations and low-quality cosmetics.
(3) Oral Medication. Take vitamin C orally or via intravenous drip at 1 gram daily for 2–3 consecutive months. It reduces dopaquinone back to dopa, inhibiting melanin formation.Sunscreens are chemical substances that absorb, scatter, or block ultraviolet rays, preventing direct and reflected UV exposure to the skin and reducing melanin production. To prevent sunburn, UV radiation between 280–320 nanometers must be blocked. To prevent tanning, UV radiation between 320–400 nanometers should also be blocked.