Poster Topical Area: Vitamins and Minerals
Location: Hall D
Poster Board Number: 528
Objective: We hypothesized that fractional intestinal d3-alpha-tocopherol (d3-α-T) absorption could be measured using the balance method to quantify the difference between intake and excretion.
Methods: Both oral d3-α-T with a breakfast shake containing 40% fat and intravenous d6-α-T (30 mg each) were administered simultaneously. Participants (n=6 women) collected all feces up to 96 h. The pooled, frozen (-80 C) fecal collection for each 24 h was weighed and a 2:1 ratio of homogenizing solution (ascorbic acid, delta-T, penta-methyl chromanol and diethylene triamine penta-acetic acid) was added. After defrosting overnight, the sample was homogenized and aliquoted for analysis by liquid chromatography/mass spectrometry of labeled and unlabeled α-T. The amounts were quantitated by comparison to authentic standards and corrected for internal standard recoveries which were more than 55%.
Results: The time course of excretion demonstrated that 72 h was sufficient to collect >90% of the total d3-α-T excreted. Fractional d3-α-T absorption was calculated from the difference in the dose administered and the sum of the d3-α-T excreted over the 96 h. Fractional absorption averaged approximately 66%. About 6% of the IV administered d6-α-T dose was excreted over the 96-h study period, with daily excretion about 0.5 mg. These data confirm that the IV-administered d6-α-T was not excreted in large amounts via the bile and feces over the 96 h. Thus, the excreted d3-α-T from the oral dosing is not extensively contaminated with d3-α-T, which has undergone enterohepatic circulation. About 6 mg unlabeled-α-T was also excreted daily, representing both unabsorbed dietary α-T and that excreted from the body.
Conclusions: In conclusion, fractional α-T absorption is about 66% when the α-T is consumed with a 40% fat meal given as a breakfast shake. By judicious use of protective antioxidants and metal-chelating reagents, fecal vitamin E could be protected from loss and accurately quantitated.
Funding Source: NIH DK081761
Ava Helen Pauling Chair
Oregon State University