Treatment of light sensitivity with carotenoids. Serum concentrations and light protection

Abstract

When beta carotene was administered to 24 volunteers as single oral doses varying from 2 to 8 mg per kg body weight, the average maximal increase of carotenoid concentration in serum was about 30 μg per 100 ml, though with great individual variations. Maximal serum concentrations were obtained mostly within 4 hr after the administration. The binding of beta carotene to human serum proteins was estimated to about 75%, by equilibrium dialysis. Carotenoids were then given as a combination of beta carotene and canthaxanthin, in multiple oral doses of 50 mg every 12th hr, to patients with light sensitive psoriasis, polymorphous light eruptions and erythropoietic protoporphyria, and also to a control group consisting of not particularly light sensitive patients with vitiligo. Maximal serum concentrations of carotenoids were reached after treatment for 20 to 40 days by most patients, with the fastest increase during the first 15 days. The maximal serum concentrations ranged from 338 to 1,219 μg per 100 ml, and the average for these 2 groups of patients was about the same. The maximal light protection factor for the group of patients with light sensitivity varied between a factor of 4 and 8, with an average value of 5.4. In the control group of patients with vitiligo the average light protection factor was 1.6 for normal, and 1.9 for vitiliginous skin. According to results obtained by light testing at various time points during the carotenoid treatment, the maximal protection factor was never estimated before about 2 to 4 mth of treatment. For patients with polymorphous light eruptions there is a positive correlation between maximal light protection and maximal serum concentration (r = 0.74), but none for the patients in the control group. In this study a pronounced difference in the light protection factor could be distinguished for light sensitive patients vis a vis a control group, in spite of the fact that the minimal erythema dose before treatment, whereas the serum concentration obtained during treatment was approximately the same for both these groups.