Antioxidant Diet May Not Prevent Stroke, Dementia
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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.
Participants answered questionnaires about how often and how much they ate 170 typical Dutch foods. The researchers looked up the antioxidant capacity of each food item, which had previously been determined by chemical analyses, and added up the capacity of all the food items to calculate each participant's antioxidant score.
"There are thousands of antioxidants in the diet, and some of them may have more antioxidant power," Devore explained. This calculation allowed the group to estimate the whole antioxidant measure, although it does not take into account how antioxidants in different food items could influence one another, she added.
"The typical Dutch diet tends to be a lot of meat, pork or beef, a lot of dairy, coffee and tea, and lower intakes of fruits and vegetables," Devore said. The diet in this older population probably did not change much over the 14-year follow-up, she added.
Between 1990, when the researchers conducted the food surveys and collected the first health reports, and 2004, 599 of the participants developed dementia and 601 had a stroke. There was no difference between the groups that had high and low antioxidant capacity and the rates of these diseases.
Devore and her colleagues also failed to find a connection between total diet antioxidant power and brain sizes among the 462 participants who got an MRI test.
These findings suggest that it is time to go back to studying individual antioxidants, but more comprehensively, Devore said.