High-Antioxidant Diet May Not Prevent Stroke, Dementia, Study Finds

By Carina Storrs

HealthDay Reporter

WEDNESDAY, Feb. 20 (HealthDay News) -- Antioxidants are celebrated as "brain foods" and "super foods," but a new study suggests that not all diets high in antioxidants reduce the risk of dementia and stroke.

The study involved more than 5,000 people in the Netherlands who were 55 years and older. Researchers determined each participant's antioxidant score, based on questionnaires about the foods they typically ate, and kept track of whether they developed dementia or had a stroke over the next 14 years.

"We asked, 'Is the [measure] of total antioxidant levels the important predictor for dementia and stroke, irrespective of what foods are contributing?'" said Elizabeth Devore, an instructor in medicine at Harvard Medical School in Boston and lead author of the study.

Although the study did not find lower rates of dementia and stroke among people with antioxidant-rich diets, similar research in other populations has come to different conclusions. For example, a study of older Italian adults found that higher antioxidant levels were linked to lower stroke risk.

The difference between the Dutch and Italian groups could lie in the types of antioxidants they eat, Devore said.

Almost 90 percent of the variability in antioxidant levels among the Dutch participants was due to coffee and tea consumption, whereas the antioxidants in the Italian cohort came largely from eating fruits and vegetables.

"There's a lot of [studies] to suggest that higher fruit and vegetable intake is associated with lower risk of stroke," Devore said. "It is possible that, though the Italian study did report diet antioxidant score, that is really being driven by those specific foods."

"It is not about total antioxidant level, it is about specific antioxidant-rich foods," Devore added.

The research in the Dutch population was published Feb. 20 in the online issue of the journal Neurology.

"It's a little bit hard to interpret the finding that total antioxidant capacity of the diet does not have a role, because of the abundance of evidence showing that oxidative stress [on cells] has a role in these diseases," said Gene Bowman, a nutritional epidemiologist at Oregon Health and Science University, in Portland.

However, "it may be that the antioxidants that they're capturing aren't the ones that are the big players," Bowman said.

Still, the idea of looking at total antioxidant capacity instead of individual antioxidant-rich foods is a new and important approach, he said.

"We've already had large observational studies showing us that certain antioxidants are linked to less stroke and dementia risk, but when giving these antioxidants in clinical trials to reduce risk for less stroke and dementia, the results have been disappointing," Bowman said.

The current study included almost 5,400 people who did not show signs of dementia and almost 5,300 people who had never had a stroke.

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