Bioefficacy of beta-carotene dissolved in oil studied in children in Indonesia.

BACKGROUND

More information on the bioefficacy of carotenoids in foods ingested by humans is needed.

OBJECTIVE

We aimed to measure the time required for isotopic enrichment of beta-carotene and retinol in serum to reach a plateau, the extent of conversion of beta-carotene dissolved in oil with use of beta-carotene and retinol specifically labeled with 10 (13)C atoms, and the intraindividual variation in response.

DESIGN

Indonesian children aged 8--11 y (n = 35) consumed 2 capsules/d, 7 d/wk, for < or =10 wk. Each capsule contained 80 microg [12,13,14,15,20,12',13',14',15',20'-(13)C(10)]beta-carotene and 80 microg [8,9,10,11,12,13,14,15,19,20-(13)C(10)]retinyl palmitate. Three blood samples were drawn per child over a period of < or =10 wk. HPLC coupled with atmospheric pressure chemical ionization liquid chromatography-mass spectrometry was used to measure the isotopic enrichment in serum of retinol with [(13)C(5)]retinol and [(13)C(10)]retinol and of beta-carotene with [(13)C(10)]beta-carotene. The beta-carotene in the capsules used had a cis-trans ratio of 3:1.

RESULTS

Plateau isotopic enrichment was reached by day 21. The amount of beta-carotene in oil required to form 1 microg retinol was 2.4 microg (95% CI: 2.1, 2.7). The amount of all-trans-beta-carotene required to form 1 microg retinol may be lower.

CONCLUSIONS

The efficiency of conversion of this beta-carotene in oil was 27% better than that estimated previously (1.0 microg retinol from 3.3 microg beta-carotene with an unknown cis-trans ratio). The method described can be extended to measure the bioefficacy of carotenoids in foods with high precision, requiring fewer subjects than other methods.