Excess vitamin E decreases canthaxanthin absorption in the rat

The recent attention given to the possible role of alpha-tocopherol (alpha-Toc) and carotenoids in the prevention and treatment of a variety of illnesses resulted in segments of the population increasing their consumption of these nutrient/antioxidants. Once consumed, alpha-Toc and carotenoids are thought to follow the same absorptive pathway and may influence each other's absorption, particularly when taken in large doses. The purpose of this study was to determine if alpha-Toc and the carotenoid, canthaxanthin (CTX), interact during absorption. Rats were intraduodenally infused with corn oil emulsions containing combinations of alpha-Toc (0 or 300 mu mol/L) and CTX (5, 10, 15, 20 mu mol/L) in a 2 x 4 factorial arrangement. Absorption was determined by measuring recovery of CTX and alpha-Toc in the mesenteric lymph. The amount of CTX in the lymph increased significantly with the amount infused into the duodenum. The overall efficiency of CTX absorption from emulsions without a-Toe averaged 12% with individual animals having a range of 8 to 18%. Efficiency of absorption was not related to concentration of CTX infused. When alpha-Toc (300 mu mol/L) was added to the oil emulsion, the absorption of CTX was decreased by at least 50%. Recovery of alpha-Toc in the lymph averaged ca. 10% and was not affected by CTX. These results suggest that concurrent consumption of a large dose of alpha-Toc may influence carotenoid bioavailability.