Amyotrophic lateral sclerosis is a progressive neurodegenerative disease that attacks nerve cells in the brain and spinal cord resulting in muscle weakness and atrophy. It is estimated to cause nearly two deaths per hundred thousand population annually, more than from Huntington's disease or multiple sclerosis.
Researchers from the Harvard School of Public Health studied data from 957,740 individuals, aged 30 or older, who were participating in the American Cancer Society's Cancer Prevention Study II.
Information on vitamin use was collected when recruiting for the study in 1982 and researchers followed up for ALS deaths from 1989 to 1998.
Occasional use of vitamin E supplements appeared to have little benefit but those using the supplements regularly for up to 10 years were 40 per cent less likely to die from the disease, report the researchers in the November issue of the Annals of Neurology.
The risk was further reduced in regular users for 10 years or more - 62 per cent lower than in nonusers of vitamin E.
No significant associations were found for use of vitamin C or multivitamins, they added.
"These results suggest that vitamin E supplementation could have a role in ALS prevention," conclude the researchers.
The findings support the theory that oxidants play a key role in the development of ALS. Earlier research found that increased brain levels of vitamin E seem to delay the onset of ALS in lab animals.