Carotenoids in erythropoietic protoporphyria and other photosensitivity diseases.

Studies in bacteria, animals and humans have demonstrated that carotenoid pigments can prevent or lessen photosensitivity by endogenous photosensitizers such as chlorophyll or porphyrins, as well as by exogenous photosensitizers such as dyes (e.g., toluidine blue) or porphyrin derivatives. The carotenoids beta-carotene and canthaxanthin have been found to be effective in the treatment of the photosensitivity associated with EPP and certain other photosensitivity diseases. No serious toxicity has been reported from their use, although the use of canthaxanthin is not recommended because of its propensity to form retinal granules. The pigments perform their protective function by quenching excited species formed by the interaction of porphyrins or dyes, light and air, thereby preventing the cellular damage which leads to the symptoms of photosensitivity.