Lee Swanson Research Update

Vitamin E May Reduce Risk of Motor Neuron Disease ALS

July 2011

Long-term use of vitamin E supplements may be associated with a reduced risk of the motor neuron disease ALS, according to new research.

The study, published in the American Journal of Epidemiology, analyzed data from over one million people from five longitudinal cohort studies, and suggested an inverse association between dietary vitamin E intake and amyotrophic lateral sclerosis (ALS), which "warrants further study."

"Among participants in cohorts with information on years of vitamin E supplement use, ALS risk declined with increasing duration of use," said the authors, led by Eilis O’Reilly from Harvard School of Public Health.

"Dietary intake of vitamin E was inversely associated with the risk of ALS, although this association was only marginally significant," they noted.

O’Reilly and her colleagues noted that, to their knowledge, the study is the largest to have examined the association between dietary and supplemental vitamin E intake and ALS.

ALS, caused by the degeneration of neurons that control muscle contractions, is the most common form of motor neuron disease.

Previous research has suggested a role for oxidative stress in the development of ALS, which is supported by the presence of biomarkers of oxidative damage in many ALS patients, and also by the occurrence of mutations in the copper/zinc superoxide dismutase gene (SOD1), a critical component of cellular antioxidant defense, in genetic ALS.

The authors used data from five studies to investigate whether vitamin E intake was associated with ALS: the Nurses’ Health Study (1976-2004), the Health Professionals Follow-Up Study (1986-2004), the Cancer Prevention Study II Nutrition Cohort (1992-2004), the Multiethnic Cohort Study (1993-2005) and the National Institutes of Health-AARP Diet and Health Study (1995-2005).

They reported that among the 1,055,546 participants, 805 developed ALS, and noted that overall use of vitamin E supplements was not associated with the development of ALS.

However, O’Reilly and her team added that within cohorts that provided information on duration of vitamin E supplement use, ALS rates were found to decline with increasing years of use.

"In this large, pooled prospective study, long-term vitamin E supplement use was associated with lower ALS rates," the authors said.

The finding that dietary vitamin E was associated with lower rates of ALS is similar to previous findings reported in a case-control study from the Netherlands in which the odds of developing ALS were 50% lower among people in the highest group of vitamin E intake from food compared with those in the lowest group, O’Reilly said.

They concluded that as such a possible protective effect of vitamin E in the development of ALS deserves further consideration.

"It remains possible that high vitamin E intake in apparently healthy persons could reduce disease risk or delay its onset," the researchers concluded.

American Journal of Epidemiology 173(6):595-602, 2011

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