Beta-carotene serum levels in patients with erythropoietic protoporphyria on treatment with the synthetic all-trans isomer or a natural isomeric mixture of beta-carotene.

The all-trans-beta-carotene serum level of patients suffering from erythropoietic protoporphyria increases substantially during continuous treatment with beta-carotene (either with the synthetic all-trans compound or with beta-carotene from a natural source consisting of a cis-trans isomeric mixture). On continuous daily ingestion, the beta-carotene serum level rose from day 0 to day 30, and no further increase was observed between day 30 and day 150. Slightly lower beta-carotene steady state serum levels were observed with the natural isomeric mixture than with synthetic beta-carotene. Higher levels of 13-cis-beta-carotene, in some cases up to 10% of the total beta-carotene, were detected after ingestion of the synthetic compound. The level of 9-cis-beta-carotene was below or close to the limit of quantification in all samples, even when the isomeric mixture containing high amounts of 9-cis-beta-carotene was applied.