Plasma RRR-alpha-tocopherol concentrations are lower in smokers than in non-smokers after ingestion of a similar oral load of this antioxidant vitamin.
1. Using deuterium-labelled alpha-tocopherol (vitamin E), the plasma kinetics of alpha-tocopherol derived from supplemental RRR-alpha-tocopherol and RRR-alpha-tocopheryl acetate were determined in asymptomatic individuals who smoke and, for comparison, in a group of healthy non-smokers. 2. Venous blood samples were withdrawn 6, 12 and 27 h after the oral administration of a gelatin capsule containing an equimolar mixture of RRR-alpha-tocopheraol and RRR-alpha-tocopheryl acetate. Plasma concentrations of endogenous and administered forms of alpha-tocopherol were determined by a combination of HPLC and GC-MS. 3. Both the free phenol and the acetate ester concentrations of alpha-tocopherol were lower in smokers than in non-smokers: 0.99 versus 1.60 (P < 0.05) and 0.66 versus 1.49 (P < 0.05) mumol/mmol cholesterol for RRR-alpha-tocopherol and RRR-alpha-tocopheryl acetate respectively. The highest concentation of alpha-tocopherol derived from administered RRR-alpha-tocopherol and its acetate ester were observed in plasma at 12 h (compared with 6-h and 27-h measurements) in most subjects. 4. Although the two forms of alpha-tocopherol were administered in equal doses, plasma from smokers contained significantly higher concentrations of RRR-alpha-tocopherol derived from the free phenol form than from the acetate form (0.99 versus 0.66 mumol/mmol cholesterol, P < 0.05, 12 h). Non-smokers did not exhibit preferential uptake of either form of vitamin E. 5. These results suggest that individuals who smoke have either a reduced ability to absorb alpha-tocopherol, particularly when it is presented as the acetate ester, or increased clearance of newly absorbed alpha-tocopherol compared with non-smokers.
Munro
L H
LH
Cardiovascular Research, Rayne Institute, St Thomas' Hospital, London, U.K.
Burton
G
G
Kelly
F J
FJ
D000284:Administration, Oral; D000328:Adult; D001682:Biological Availability; D003903:Deuterium; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007408:Intestinal Absorption / Q000502:physiology; D012907:Smoking / Q000097:blood*; D013997:Time Factors; D024505:Tocopherols; D014810:Vitamin E / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood*; D024502:alpha-Tocopherol / Q000031:analogs & derivatives*
D014810:Vitamin E; D003903:Deuterium; D024502:alpha-Tocopherol; D024505:Tocopherols