Studies on the bioavailability of the provitamin A carotenoid, (beta)-carotene, using human exfoliated colonic epithelial cells

The possibility of using exfoliated colonic epithelial cells for assessing the bioavailability of (beta)carotene was examined. Analysis of exfoliated colonic epithelial cells showed the presence of (beta)carotene and vitamin A. The (beta)-carotene content was significantly lower in cells from stool samples of subjects on a (beta)-carotene-poor diet than those receiving a single dose of a (beta)carotene supplement. Colonic epithelial cells isolated from stool samples collected daily during a wash-out period while the subjects were on a (beta)-carotene-poor diet showed a steady decrease in (beta)-carotene content, reaching the lowest value on day 7. Kinetic analysis showed that a single dose of a (beta)-carotene supplement in the form of spirulina (Spirulina platensis) or agathi (Sesbania grandiflora) after the wash-out period caused an increase in the (beta)-carotene content after a lag period of 5-7 d, but the vitamin A levels during these periods were not significantly affected. Analysis of plasma (beta)-carotene concentration also showed similar changes, which correlated with those of exfoliated colonic cells. A relationship between the (beta)-carotene content of the diet and that of the colonic epithelial cells suggests that analysis of the (beta)-carotene content in exfoliated human colonic epithelial cells is a useful non-invasive method to assess the bioavailability of provitamin A (beta)-carotene.