Abstract: Compositions of high-purity natural beta-carotene and of the 9-cis isomer of beta-carotene are provided, as are methods for the production of these compositions from plant matter, conveniently algae such as Dunaliella species. Typically, the compositions contain at least about 5% 9-cis beta-carotene and less than or equal to 40% of all-trans-beta-carotene, and in some cases may contain 75% 9-cis beta-carotene or higher. The compositions are suitable for administration to humans or other animals, particularly for oral delivery, in a variety of formulations and dosages as pharmaceutical agents or as dietary supplements.