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-alpha-tocopherol in 12 healthy adults. Six men and 6 women, aged 27 +/- 6 y, each ingested 1.81 nmol of 14C-RRR-alpha-tocopherol; each dose had 3.70 kBq of 14C. Complete collections of urine and feces were made over the first 21d from dosing. Serial blood samples were drawn over...

BACKGROUND: To our knowledge, there is no direct information on lycopene metabolism in humans. OBJECTIVE: The objective of this study was to quantify the long-term human bioavailability of lycopene in plasma and skin after a single dose of (14)C-lycopene and to profile the metabolites formed. DESIGN: We preselected 2 male subjects as lycopene absorbers and gave them an oral dose of 10 mg synthetic lycopene combined with 6 µg [6,6',7,7'-(14)C]lycopene (30,000 Bq; 92% trans lycopene)....