Vitamin E serum levels and controlled supplementation and risk of amyotrophic lateral sclerosis.

There are no observational studies or controlled trials of amyotrophic lateral sclerosis (ALS) and circulating α-tocopherol (vitamin E) for prevention of ALS. This study addresses that gap. The study population comprised 29,127 Finnish male smokers, aged 50-69 years, who participated in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, which is both a prospective cohort and a randomized, double-blind, placebo-controlled trial of α-tocopherol (50 mg/day) and β-carotene (20 mg/day). Serum α-tocopherol and β-carotene was assayed at baseline (1985 - 1988). Follow-up (median 16.7 years) continued through 2004. ALS cases were identified through the national Hospital Discharge Register with diagnostic verification by hospital records and death certificates. During 407,260 person-years of follow-up, 50 men were identified with ALS. For males with serum α-tocopherol concentration above the median (≥ 11.6 mg/l), the age-adjusted relative risk (RR) compared to α-tocopherol below the median, was 0.56 (95% confidence interval 0.32 - 0.99), p = 0.046. The RR among α-tocopherol supplement recipients was 0.75 (95% CI 0.32 - 1.79), p = 0.52. Neither serum β-carotene level nor β-carotene supplementation was associated with ALS. In conclusion, the results are consistent with a hypothesized protective effect of α-tocopherol on ALS risk. However, pooled analyses of cohorts with serum and controlled trials are needed to clarify the role of α-tocopherol in ALS risk.