The study, published in American Journal of Epidemiology, analysed 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, USA.
“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.
Amyotrophic lateral sclerosis (ALS), caused by the degeneration of neurones that control muscle contractions, is the most common form of motor neurone 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 defence, 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,” said the authors.
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 per cent lower among people in the highest group of vitamin E intake from food compared with those in the lowest group, said O’Reilly.
They concluded that as such a possible protective effect of vitamin E in the development of ALS deserves further consideration.
Vitamin E role
The authors noted that vitamin E is an important cellular antioxidant which has been shown to delay the onset of ALS in an animal model.
“Although promising at the time, vitamin E supplementation was found to be ineffective in randomized trials of patients with ALS,” said O’Reilly and her colleagues.
“However, it remains possible that high vitamin E intake in apparently healthy persons could reduce disease risk or delay its onset … Therefore, we conducted a larger prospective study to examine whether supplemental and dietary vitamin E were related to risk of ALS using data from 5 large ongoing cohort studies,” they added.
Source: American Journal of Epidemiology
Volume 173, Issue 6, Pages 595-602., doi: 10.1093/aje/kwq416
“Vitamin E Intake and Risk of Amyotrophic Lateral Sclerosis: A Pooled Analysis of Data From 5 Prospective Cohort Studies”
Authors: H. Wang, É.J. O'Reilly, M.G. Weisskopf, G. Logroscino, et al.