Use of exfoliated cells to study tissue-specific levels of beta-carotene in humans.

This study was designed to explore the feasibility of using exfoliated cells to study beta-carotene incorporation into different epithelial tissues in humans. Exfoliated cells were collected from the oral cavities (by brushing the oral mucosa) and from the urogenital tracts (by centrifuging urine samples) of 36 females and basal levels of beta-carotene (without oral supplementation) were determined. Beta-carotene levels in cells from the two sites differed significantly, although a weak correlation was observed. As a second aspect of the study, 10 of these females were given oral supplementation with beta-carotene (90 mg twice weekly for 4 weeks). Beta-carotene levels increased significantly in both exfoliated urogenital tract (6.8-fold) and oral mucosa (5-fold) cells. However, the supplemented levels remained significantly different for the two types of cells. Beta-carotene levels did not change in individuals receiving a placebo treatment (n = 7). These studies suggest that exfoliated cells collected from different sites may be of value in quantifying tissue levels of beta-carotene during cancer intervention trials.