Serum carotenoids and retinol of human subjects consuming carrot juice

The effects of carrot juice consumption on serum alpha- and betacarotene, total carotenoid and retinol levels were studied in 10 adulted volunteers, age 23-48 years. Five subjects consumed 16 ounces of juice per day for 7 days and then 8 ounces every other day for the next 7 days. Another group of 5 subjects consumed 16 ounces of juice per day for 7 days and then received no carrot juice for the next 7 days. Blood serum collected from both groups at the start of the study and after day 7 and day 14 was analyzed by HPLC and spectrophotometry for carotenoid and retinol concentration. When consumption of carrot juice was continuous, alpha-carotene and total carotenoids increased at 1 week and stabilized, while beta-carotene continued to increase over the course of the 2 weeks. When carrot juice consumption occurred for 1 week and was then terminated, alpha-and beta-carotene rose at 1 week and then stabilized, while total carotenoids rose at 1 week and returned to baseline level after the week of withdrawal. Serum retinol levels did not change for either group throught the study period.