Dietary α‐, β‐, γ‐ and δ‐tocopherols in lung cancer risk

Abstract

Studies of vitamin E and cancer have focused on the α‐tocopherol form of the vitamin. However, other forms of vitamin E, in particular γ‐tocopherol may have unique mechanistic characteristics relevant to lung cancer prevention. In an ongoing study of 1,088 incident lung cancer cases and 1,414 healthy matched controls, we studied the associations between 4 tocopherols (α‐, β‐, γ‐, and δ‐tocopherol) in the diet and lung cancer risk. Using multiple logistic regression analysis, the adjusted odds ratios (OR) and 95% confidence intervals (CI) of lung cancer for increasing quartiles of dietary α‐tocopherol intake were 1.0, 0.63 (0.50–0.79), 0.58 (0.44–0.76) and 0.39 (0.28–0.53), respectively (p‐trend < 0.0001). For dietary intake of β‐tocopherol, the OR and 95% CI for all subjects were: 1.0, 0.79 (0.63–0.98), 0.59 (0.45–0.78) and 0.56 (0.42–0.74), respectively (p‐trend < 0.0001). Similar results for dietary γ‐tocopherol intake were observed: 1.0, 0.84 (0.67–1.06), 0.76 (0.59–0.97) and 0.56 (0.42–0.75), respectively (p‐ trend = 0.0002). No significant association between δ‐tocopherol intake and lung cancer risk was detected. When the 4 tocopherols were summed as total tocopherol intake, a monotonic risk reduction was also observed. When we entered the other tocopherols in our model, only the association with dietary α‐tocopherol intake remained significant; i.e., increasing intake of dietary α‐tocopherol accounted for 34–53% reductions in lung cancer risk. To the best of our knowledge, this is the first report of the independent associations of the 4 forms of dietary tocopherol (α‐, β‐, γ‐ and δ‐tocohperol) on lung cancer risk. Given the limitations with case‐control studies, these findings need to be confirmed in further investigations.