Abstract
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.
Acknowledgements
We thank Barry Graubard and Sarah Daugherty of NCI, Maret Traber of the Linus Pauling Institute of Oregon State University, and Matthew Longnecker of the National Institute of Environmental Health Sciences for their thoughtful contributions to this study and Dominick Parisi and Kirk Snyder of Information Management Services, Inc. for biomedical computer assistance.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
This research was supported by the Intramural Research Program of the National Institutes of Health, National Cancer Institute, and the U.S. Public Health Service, and in part by contracts from the United States National Cancer Institute, National Institutes of Health, Department of Health and Human Services.