That means the natural form has something the synthetic does not.
In experiments at Israel's National Institute of Oceanography, the researchers gave young, healthy men supplements of either natural beta-carotene from Dunaliella algae or synthetic beta-carotene. Blood analyses showed the presence of the all-trans isomer of beta-carotene, but not the 9-cis form found in natural beta-carotene. However, the researchers looked for‹and found‹9-cis metabolic byproducts, indicating the presence and activity of the natural isomer.