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Much research has shown that oxidative stress plays a key role in the development of neurodegenerative disorders, such as Alzheimer's and Parkinson's disease. As a result, antioxidant supplements like vitamin E and selenium have been proposed to prevent dementia. Yet a new study on older men published online March 20, 2017, by JAMA Neurology found no evidence they can help.
The Prevention of Alzheimer's Disease by Vitamin E and Selenium clinical trial included 7,540 men, average age of 67. Over a five-year period, the men were randomly assigned to receive 400 international units of vitamin E each day, 200 micrograms of selenium, both supplements, or a placebo. The supplements were stopped and 3,786 of these men agreed to be followed for an additional six years. They were routinely screened for cognitive problems and encouraged to see their doctor if the results suggested any kind of cognitive impairment.
By the end of the study only 4.4% of the men had developed dementia, but there was no difference in dementia rates between the four supplement groups. However, the researchers pointed out that the results could be different depending on factors like a longer duration or changes in dosages and that more research is needed.
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