Variations in the uptake of beta-carotene in the oral mucosa of individuals after 3 days of supplementation.

Variations in the response of individuals to beta-carotene supplementation were studied by measuring the accumulation of beta-carotene in oral mucosa cells. Beta-carotene was administered orally to 178 individuals for 3 consecutive days, exfoliated oral mucosa cells were collected by brushing the entire oral mucosa on the 7th day following supplementation, and the beta-carotene content was measured by HPLC analysis of the pronase-treated cells. The rise in beta-carotene levels in the oral mucosa following supplementation varied considerably. Significant differences in mean beta-carotene levels in the oral mucosa were observed in 4 population groups. After supplementation, beta-carotene levels increased by factors of 10.3 (100 Mile House), 7.8 (Williams Lake), 6.9 (Lytton) and 3.4 (Vancouver), respectively. This difference in mean beta-carotene values is due to there being different proportions of weak and strong responders in the various population groups. Neither peak levels nor increases in beta-carotene levels were correlated with base-line concentrations of beta-carotene in the pre-supplementation samples. A second supplementation was given to 54 individuals several months after the initial supplementation. Of 17 weak responders in the first supplementation study, 10 (58.8%) individuals again showed only a small increase. A time-course study revealed that low responders showed no significant changes in beta-carotene levels over the 21 days following supplementation. Particular attention should be paid to weak responders when results of intervention trials using beta-carotene are interpreted.