Association of Serum γ-Tocopherol Levels with Mortality: The Multiethnic Cohort Study

BACKGROUND/OBJECTIVES: γ-Tocopherol has unique properties that protect against nitrogen oxide-mediated cellular damage. To elucidate the potential role of γ-tocopherol in the aging process, we examined the associations of serum γ-tocopherol levels with all-cause and cause-specific mortality. SUBJECTS/METHODS: Among participants in the biorepository subcohort of the Multiethnic Cohort Study, pre-cancer diagnostic serum γ-tocopherol levels were measured in a subset of 3904 men and 4461 women. Of these, 22.7% of men and 13.5% of women died during a mean follow-up time of 9.6±2.6 years. Hazard ratios (HRs) and 95% confidence intervals (95%CIs) for mortality associated with γ-tocopherol were estimated by Cox proportional hazards regression. RESULTS: Positive associations of serum γ-tocopherol with all-cause, cancer and cardiovascular disease mortality (CVD) (P(trend)<0.05) were detected after adjusting for age, race-ethnicity and serum cholesterol levels. The respective HRs (95%CIs) for the highest versus the lowest sex-specific γ-tocopherol quartile were 1.43 (1.17–1.74), 1.79 (1.22–2.64), and 1.52 (1.10–2.11) for men and 1.58 (1.25–2.00), 1.59 (1.05–2.41), and 1.59 (1.07–2.37) for women. Associations remained significant for all-cause mortality among women after further adjusting for smoking variables and history of cancer, CVD, diabetes, and hypertension at cohort entry (highest vs. lowest γ-tocopherol quartile: HR=1.38; 95%CI=1.08–1.75; P(trend)= 0.005). Overall, associations with all-cause mortality were consistent across race/ethnicity and were significant in three of ten sex-specific racial/ethnic groups in the fully adjusted models with no interactions between ethnicity and γ-tocopherol. CONCLUSIONS: The positive association between γ-tocopherol and mortality suggests a potential physiological role for γ-tocopherol in response to pathological conditions.