The results of many animal and cell experiments support the notion that foodborne antioxidants protect and enhance brain function, with positive findings attached to tea, berries, turmeric, grapes, and cocoa, among other foods and fruit juices rich in polyphenol-type flavonoid antioxidants.
The positive effects seen in lab and animal studies range from beneficial effects on cell signaling to direct antioxidant effects on cell-damaging free radicals and increases in blood flow to the brain.
But surprisingly few studies have looked for confirming evidence from human population or clinical studies.
A French team now reports that diets rich in flavonoids—the antioxidant compounds in fruit, vegetables, coffee, tea, and chocolate—could reduce the decline in mental function associated with aging.
The researchers, based at INSERM—France's equivalent of the US National Institutes of Health—recruited 1,640 subjects with an average age of 77 who showed no signs of dementia at the start of the study.
The participants’ estimated intake of flavonoids was assessed using diet surveys administered four times over a 10 year period.
Their level of cognitive function was measured using standard tests.
After adjusting the results for age, sex, and education level, the French group linked higher flavonoid intake with better mental performance at the start of the study and less risk of mental decline over time.
The people with the highest flavonoid intakes displayed better brain function than those with the lowest intakes.
While these encouraging results need confirmation in controlled clinical trials, they fit with everything we know about the effects of flavonoids at the cellular level, and their general ability to neutralize cell-damaging free radicals and increase blood flow to the brain.
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