This Kinetic, Bioavailability, and Metabolism Study of RRR-a-Tocopherol in Healthy Adults Suggests Lower Intake Requirements than Previous Estimates  

Oleh:

Novotny, Janet A. ; Fadel, James G. ; Holstege, Dirk M.

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: JN: The Journal of Nutrition vol. 142 no. 12 (Dec. 2012), page 2105-2111 .
Topik: NUTRIENT; Nutrient Requirements; Optimal Nutrition

Ketersediaan

Perpustakaan FK Nomor Panggil: J42.K.2012.02 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

Kinetic models enable nutrient needs and kinetic behaviors to be quantified and provide mechanistic insights into metabolism. Therefore, we modeled and quantified the kinetics, bioavailability, and metabolism of RRR-a-tocopherol in 12 healthy adults. Six men and 6 women, aged 27 ± 6 y, each ingested 1.81 nmol of [5-14CH3]-(2R, 4'R, 8'R)-a-tocopherol; each dose had 3.70 kBq of 14C. Complete collections of urine and feces were made over the first 21 d from dosing. Serial blood samples were drawn over the first 70 d from dosing. All specimens were analyzed for RRR-a-tocopherol. Specimens were also analyzed for 14C using accelerator MS. From these data, we modeled and quantified the kinetics of RRR-a-tocopherol in vivo in humans. The model had 11 compartments, 3 delay compartments, and reservoirs for urine and feces. Bioavailability of RRR-a-tocopherol was 81 ± 1%. The model estimated residence time and half-life of the slowest turning-over compartment of a-tocopherol (adipose tissue) at 499 ± 702 d and 184 ± 48 d, respectively. The total body store of RRR-a-tocopherol was 25,900 ± 6=220 µmol (11 ± 3 g) and we calculated the adipose tissue level to be 1.53 µmol/g (657 µg/g). We found that a daily intake of 9.2 µmol (4 mg) of RRR-a-tocopherol maintained plasma RRR-a-tocopherol concentrations at 23 µmol/L. These findings suggest that the dietary requirement for vitamin E may be less than that currently recommended and these results will be important for future updates of intake recommendations.

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