Zaynoun S T, Hunter J A, Darby F J, Zarembski P, Johnson B E, Frain-Bell W
Br J Dermatol. 1977 Dec;97(6):663-8. doi: 10.1111/j.1365-2133.1977.tb14274.x.
In a group of 19 subjects suffering from erythropoietic protoporphyria the administration of beta-carotene appeared to produce improvement based on a subjective assessment of alterations in exposure times required to produce the symptoms and signs of the condition. This clinical improvement however failed to show a direct correlation with the prophyrin levels in blood and faeces, or with the estimation by phototesting of the minimal response dose within the action spectrum of 400-600 nm.