Carotenoid profile and retinol content in human serum — simultaneous determination by high-pressure liquid chromatography (HPLC)

Abstract

A reversed-phase HPLC method developed for the simultaneous determination of carotenoids and retinol in foods of vegetable and animal origin was applied to the study of 100 samples of human serum. The subjects were urban adult Malaysians of Malay, Chinese and Indian descent with a mean age of 52.8 years (range 17–78 years). For comparison, all serum samples were also simultaneously determined using the direct spectrophotometric method for carotenoids and the Carr-Price colorimetric method for retinol. Compared to the conventional methods, the HPLC method was found to give significantly higher results for retinol and total carotenoid concentrations. The major advantages of the liquid chromatographic method are that it is more specific and that it overcomes the problems associated with the Carr-Price method. In addition, only the HPLC procedure could provide an account of the serum carotenoid profile, a knowledge of which is now of increasing health importance in view of the possible inverse association of carotenoid intake and some forms of cancer. Six major carotenoids — lutein, cryptoxanthin, lycopene, γ-carotene, α-carotene and β-carotene — were quantitated, the most abundant being lutein and cryptoxanthin, each contributing to about one quarter of all the carotenoids quantitated. β-carotene and lycopene were the next abundant carotenoids, each contributing to about 20% of all carotenoids. γ- and α-carotenes together made up about 10% of all the carotenoids detected and quantitated. The mean content of total carotenoids was 196.0 ± 83.2 μg/dl, with no statistically significant difference between levels for female and male subjects. The mean serum retinol level was 74.2 ± 23.0 μg/dl and none of the subjects in this study could be regarded to be vitamin A deficient.