Astaxanthin

Astaxanthin is the most potent singlet oxygen quencher known (approximately 6,000× more potent than vitamin C), with double-blind clinical evidence showing increased minimal erythema dose and reduced UV-induced transepidermal water loss at 4 mg/day oral dosing. Primary formulation challenges include intense orange-red pigmentation (cosmetically limiting above 0.01%) and poor water solubility requiring nanoemulsions or solid lipid nanoparticles for optimal delivery. Typical cosmetic use range is 0.001–0.05% with excellent tolerability and no sensitization at these concentrations.

No FDA restrictions for topical cosmetic use. GRAS for dietary supplement use. No specific cosmetic concentration limits. Clinical photoprotection evidence from 4 mg/day oral supplementation — topical and oral routes have separate evidence bases.