biostudies-literatureChuang JCNCRR NIH HHSNIDDK NIH HHS1482-8https://www.ebi.ac.uk/biostudies/studies/S-EPMC3138640biostudies-literatureUnknown141(8)Half-lives of α-tocopherol in plasma have been reported as 2-3 d, whereas the Elgin Study required >2 y to deplete α-tocopherol, so gaps exist in our quantitative understanding of human α-tocopherol metabolism. Therefore, 6 men and 6 women aged 27 ± 6 y (mean ± SD) ingested 1.81 nmol, 3.70 kBq of [5-(14)CH(3)]-(2R, 4'R, 8'R)-α-tocopherol. The levels of (14)C in blood plasma and washed RBC were monitored frequently from 0 to 460 d while the levels of (14)C in urine and feces were monitored from 0 to 21 d. Total fecal elimination (fecal + metabolic fecal) was 23.24 ± 5.81% of the (14)C dose, so feces over urine was the major route of elimination of the ingested [5-(14)CH(3)]-(2R, 4'R, 8'R)-α-tocopherol, consistent with prior estimates. The half-life of α-tocopherol varied in plasma and RBC aThe Journal of nutritionQuantitation of [5-14CH3]-(2R, 4'R, 8'R)-α-tocopherol in humans.PMC3138640R01 DK081551P41 RR013461R01 DK 081551UL1 RR024146RR13461Chuang JCClifford AJKim SHFadel JGNambiar KPHolstege DMMatel HDfalseQuantitation of [5-14CH3]-(2R, 4'R, 8'R)-α-tocopherol in humans.Half-lives of α-tocopherol in plasma have been reported as 2-3 d, whereas the Elgin Study required >2 y to deplete α-tocopherol, so gaps exist in our quantitative understanding of human α-tocopherol metabolism. Therefore, 6 men and 6 women aged 27 ± 6 y (mean ± SD) ingested 1.81 nmol, 3.70 kBq of [5-(14)CH(3)]-(2R, 4'R, 8'R)-α-tocopherol. The levels of (14)C in blood plasma and washed RBC were monitored frequently from 0 to 460 d while the levels of (14)C in urine and feces were monitored from 0 to 21 d. Total fecal elimination (fecal + metabolic fecal) was 23.24 ± 5.81% of the (14)C dose, so feces over urine was the major route of elimination of the ingested [5-(14)CH(3)]-(2R, 4'R, 8'R)-α-tocopherol, consistent with prior estimates. The half-life of α-tocopherol varied in plasma and RBC a2011-01-01T00:00:00Z2011 Aug2025-04-05T10:03:19.421Z2019-03-27T03:07:12ZS-EPMC31386402171547010.3945/jn.111.138925