BETA-CAROTENE ISOMERS IN HUMAN SERUM, BREAST-MILK AND BUCCAL MUCOSA CELLS AFTER CONTINUOUS ORAL DOSES OF ALL-TRANS AND 9-CIS BETA-CAROTENE

The concentrations of all-trans beta-carotene (tBC) and 9-cis beta-car otene (9cBC) isomers in serum, breast milk and buccal mucosa cells wer e determined after continuous oral doses as a simple, non-invasive met hod to determine whether differences in tissue uptake are important de terminants of serum responses. Twelve healthy lactating women were rec ruited for a nonresidential study. On d 1, blood samples were obtained from fasting subjects for baseline concentrations of beta-carotene is omers. Over a 1-wk period, subjects were given either seven doses of a placebo (n = 4) or seven doses of naturally occurring BC (n = 8) deri ved from Dunaliella bardawil (64 mg tBC, 69 mg 9cBC). Subjects were in structed to consume a single beta-carotene dose along with a meal cont aining adequate fat each day for 1 wk, On d 2, 3, 5 and 8, blood sampl es and breast milk were collected from fasting subjects. On d 1 and 8, buccal mucosa cells were collected. Samples were analyzed for caroten oids by HPLC. In the experimental group, the mean serum concentration of tBC significantly increased to seven times the baseline level by th e end of the supplementation period (P < 0.0001). The serum concentrat ion of 9cBC significantly increased to three times the baseline level by the end of the supplementation period (P < 0.0001). The changes in milk and buccal mucosa cells levels of tBC and 9cBC followed a pattern similar to that for serum, showing significant increases at the end o f the supplementation period. In the control group, the serum, milk an d buccal mucosa cell concentrations of BC isomers did not change. This study confirms the previously reported differences in the serum respo nse curves of tBC and 9cBC and provides evidence that there is no diff erence in tissue uptake of tBC and 9cBC.