Dietary intake of antioxidants, particularly vitamins C and E, may lower the risk of developing Alzheimer's, according to recent evidence.
In the first of two reports, Dutch researchers collected data on 5395 subjects who were at least 55 years of age and free of dementia. After an average of six years, 197 had dementia and 146 of these were diagnosed as due to Alzheimer's disease.
After adjusting for risk factors such as age, sex, overall mental health, alcohol intake, education, smoking and diet, the researchers found that a high dietary intake of vitamins C and E was associated with a nearly 20 per cent reduced risk of Alzheimer's (JAMA, 2002; 287: 3223-29).
Smokers benefited from a nearly 42 per cent reduction in risk when taking vitamins C and E, and beta-carotene and flavonoids also helped lower smokers' risk.
In a second report, researchers at the Rush Institute for Healthy Aging in Chicago found that the more vitamin E-containing foods eaten, the lower the risk of developing Alzheimer's.
To reach this conclusion, data were collected on 815 community-dwelling men and women, aged 65 and older, and without Alzheimer's, and monitored their diets for nearly four years.
Those with the highest dietary vitamin E intake had a 70 per cent lower risk of developing Alzheimer's disease compared with those with the lowest intakes.
In this study, however, no protective effect was seen with supplements of vitamin E and C, multivitamins or beta-carotene (JAMA, 2002; 287: 3261-3).
Nevertheless, the overall conclusions of these reports are in line with those of a recent study suggesting that Alzheimer's is largely an environmental illness.
This study looked at 2459 healthy, community-dwelling residents in a non-industrialised city in Nigeria and compared them with a similar group of healthy, community-dwelling African-Americans living in a busy, industrialised US city. Both groups were followed for around five years.
Rates for both dementia and Alzheimer's were more than twice as high in the African-Americans. It is suggested that exposure to pollutants, heavy metals and processed foods may each have a role to play in the development of Alzheimer's (JAMA, 2001; 285: 739-47).