1. Using deuterium-labelled α-tocopherol (vitamin E), the plasma kinetics of α-tocopherol derived from supplemental RRR-α-tocopherol and RRR-α-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 Venous blood samples were withdrawn 6, 12 and 27 h after the oral administration of a gelatin capsule containing an equimolar mixture of RRR-α-tocopherol and RRR-α-tocopheryl acetate. Plasma concentrations of endogenous and administered forms of α-tocopherol were determined by a combination of HPLC and GC-MS.
3. Both the free phenol and the acetate ester concentrations of α-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) μmol/mmol cholesterol for RRR-α-tocopherol and RRR-α-tocopheryl acetate respectively. The highest concentation of α-tocopherol derived from administered RRR-α-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 α-tocopherol were administered in equal doses, plasma from smokers contained significantly higher concentrations of RRR-α-tocopherol derived from the free phenol form than from the acetate form (0.99 versus 0.66 μmol/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 α-tocopherol, particularly when it is presented as the acetate ester, or increased clearance of newly absorbed α-tocopherol compared with non-smokers.