Researchers found that people who ate or drank lots of coffee, tea, oranges and red wine were just as likely to develop neurological problems over the next 14 years as those who skimped on antioxidant-rich foods.
"The literature on antioxidants and dementia has been mixed," said Elizabeth Devore, who led the new research at Brigham and Women's Hospital in Boston.
Although there's some evidence that specific vitamins have a protective effect in the brain, she said it's unclear whether that's the case for all antioxidants - which include vitamin C, vitamin E, selenium and flavonoids.
"There is the thought that overall antioxidants might be helpful, but it's also true that if you actually look at the individual antioxidants, there's not necessarily a reason to think that one would behave exactly the same way in the body as the next."
The Netherlands-based study included 5,395 people aged 55 years and older, who reported their usual consumption of 170 different foods in 1990.
Devore and her colleagues tracked those participants over the next 14 years, during which 599 were diagnosed with dementia - including 484 with Alzheimer's disease - and 601 had a first stroke.
People who consumed the most antioxidants, according to an analysis of their diets, were just as likely to end up having either of those neurological disorders as study participants who hardly got any antioxidants.
That pattern held after the researchers took into account people's ages, how much they ate in general and whether they smoked, according to the findings published Wednesday in Neurology.
There was also no link between total dietary antioxidants and white or gray matter volume in the brain, according to scans done on 462 of the participants.
Since the study looked only at foods consumed, it can't address whether antioxidant supplements may impact dementia or stroke risk, according to Devore.
Her team concludes that it's still likely certain individual antioxidants have positive effects on the brain.
"There have been a number of studies that have shown that higher intake of dietary vitamin E is associated with lower risk of dementia," Devore told Reuters Health. The same goes for vitamin C and stroke risk, she added.
That suggests people should continue eating plenty of fruits and vegetables, including berries, and seek out specific antioxidants, she said.
"For dementia specifically and stroke specifically, if you're worried about those you should try to take in vitamin E for dementia and vitamin C for stroke."
SOURCE: http://bit.ly/csS3ol Neurology, online February 20, 2013.