Comparison of vitamin C bioavailability after multiple or single oral dosing of different formulations in sheep.

The purpose of this study was to compare the bioavailability of either multiple or single oral supplementation of different formulations of vitamin C and intra-duodenal supplementation of one form of vitamin C in sheep. Formulations used in the study were (1) ascorbic acid fine powder (AA); (2) ascorbic acid coated with ethyl cellulose (EC); (3) Rovimix STAY-C (SC); (4) sodium ascorbate (SA); (5) Rovimix C (RC). The bioavailability of vitamin C formulations was assessed by the changes in plasma ascorbic acid concentrations, area under the curve (AUC) and area under the curve above its basal concentration (AUCabove) values. There was no effect of single oral supplementation on bioavailability of vitamin C. Multiple dosing over a period of 28 days of oral supplementation of all five formulations resulted in higher AUCabove values. Furthermore, multiple oral supplementation of RC increased plasma concentrations of ascorbic acids and AUC values. Single intra-duodenal supplementation of ascorbic acid resulted in significantly higher AUC when compared with oral supplementation of the same vitamin C.