Objective
Tocotrienols (T3s) have been hypothesized to have greater antioxidant capacity than tocopherols (Ts) due to differences in biokinetics that affect their absorption and function. The present trial compares the antioxidant effectiveness following postprandial challenge of two different doses of α-T or palm T3-rich fraction (TRF) treatments and evaluates their dose-response effects on antioxidant status.

Methods
Ten healthy volunteers were given four different doses of vitamin E formulations (268 mg α-T, 537 mg α-T, 263 mg TRF or 526 mg TRF) in a cross-over postprandial trial. Blood was sampled at 0, 2, 4, 5, 6 and 8 hours after meal consumption and plasma antioxidant status, including total glutathione, superoxide dismutase, malondialdehyde (MDA), ferric reducing antioxidant potential and trolox-equivalent antioxidant capacity, was analyzed.

Results
Supplementation with the different doses of either α-T or TRF did not significantly improve overall antioxidant status. There was no significant difference in overall antioxidant status among treatments at the different doses compared. However, a significant dose-response effect was observed for plasma MDA throughout the 8-hour postprandial period. MDA was significantly lower after the 537 mg α-T treatment, compared to the 268 mg α-T treatment; it was also lower after the 526 mg TRF treatment compared to the 263 mg TRF treatment (P < 0.05).

Conclusion
T3 and α-T demonstrated similar antioxidant capacity, despite markedly lower levels of T3 in blood and lipoproteins, compared to α-T.

Key words: Vitamin E, Tocopherols, Tocotrienols, Antioxidants, Postprandial