Vitamin E intake and the lung cancer risk among female nonsmokers: a report from the Shanghai Women's Health Study.

Vitamin E includes several tocopherol isoforms, which may reduce lung cancer risk, but past studies evaluating the association between vitamin E intake and lung cancer risk were inconsistent. We prospectively investigated the associations between tocopherol intake from diet and from supplements with lung cancer risk among 72,829 Chinese female nonsmokers aged 40-70 years and participating in the Shanghai Women's Health Study (SWHS). Dietary and supplement tocopherol exposure was assessed by a validated food-frequency questionnaire at baseline and reassessed for change in intake during follow-up. Cox proportional hazards models with time-dependent covariates were used to calculate multivariate-adjusted hazard ratios (HRs) and 95% confidence interval (CIs) for lung cancer. After 12.02 years of follow-up, 481 women were diagnosed with lung cancer. Total dietary tocopherol was inversely associated with lung cancer risk among women meeting dietary guidelines for adequate intake (AI) of tocopherol (14 mg/day or more: HR: 0.78; 95% CI 0.60-0.99; compared with the category less than AI). The protective association between dietary tocopherol intake and lung cancer was restricted to women exposed to side-stream smoke in the home and workplace [HR = 0.53 (0.29-0.97), p-trend = 0.04]. In contrast, vitamin E supplement use was associated with increased lung cancer risk (HR: 1.33; 95% CI: 1.01-1.73), more so for lung adenocarcinoma risk (HR: 1.79; 95% CI: 1.23-2.60). In summary, dietary tocopherol intake may reduce the risk of lung cancer among female nonsmokers; however, supplements may increase lung adenocarcinoma risk and requires further investigation.