Natural substances found in deep-coloured foods such as tea are linked to a lower risk of dementia, according to new research.
And the international and Australian researchers said the link was higher among those who are generally more at risk of developing the condition.
People with the highest ‘flavodiet’ scores had a lower risk of dementia compared with those with the lowest scores, with drinking just four servings of tea per day also associated with a lower risk for dementia.
Flavonoids, already known for various health benefits, are found in a range of fruits and vegetables including berries and leafy greens, as well as tea, red wine and dark chocolate.
ECU’s Dr Nicola Bondonno said their consumption had been linked to a decrease in the risk of type 2 diabetes, certain cancers and cardiovascular events, and the research from ECU had shown their potential role in reducing the risk of dementia.
“The findings from this large cohort study of more than 120,000 UK Biobank participants suggest that consuming six additional servings per day of flavonoid-rich foods, specifically tea, red wine and berries, was associated with a lower risk of dementia, with the strongest associations observed for tea,” Dr Bondonno said.
“We were also able to show, for the first time in our knowledge, that these associations were evident in participants at high genetic risk of dementia and those with modifiable risk factors, including depression and hypertension, but not in those without.
“Intakes of tea have previously been associated with lower dementia risk in this cohort, with a 14% lower dementia risk in participants consuming more than four servings per day of tea compared with those who did not consume tea.”
This was just half of the risk observed for the combination of flavonoid-rich foods in the current analyses, highlighting the benefits of consuming a range of flavonoid-rich foods for lowering dementia risk.
“Our findings appeared to be driven by intakes of tea, berries, and red wine, with the greatest risk reduction observed in participants consuming at least two of the following: five servings per day of tea, one serving per day of red wine, and 0.5 servings per day of berries,” Dr Bondonno said.
“These findings are supported by our analyses of flavonoid subclasses showing that the anthocyanin, flavan-3-ol, and flavone subclasses, of which tea, red wine, and berries are among the top contributors, had the strongest associations with dementia risk – meaning that modest changes to the diet could increase flavonoid levels to that required to lower a person’s dementia risk.”
Of the flavonoid subclasses, higher intakes of anthocyanins (found in red wine and berries), flavan-3-ols (tea), flavonols (tea, wine and berries), and flavones (the pigments in blue and white flowering plants) were associated with a lower risk of dementia.
Dr Bondonno noted that the study also showed a more pronounced protective association of flavonoid-rich food with dementia risk in participants at high genetic risk of dementia.
“Another key finding was that the association between flavonoid-rich food consumption and dementia risk was observed in participants with depressive symptoms at baseline,” she said.
“Depression activates many of the mechanistic pathways known to be targeted by flavonoids, including increased proinflammatory cytokines, reduced cerebral blood flow, and modified vascular risk factors.
“However, while red wine, a key contributor of anthocyanin intake, has been shown to be beneficial for both dementia and depression at moderate intakes, the associations among alcohol intake, depression, and dementia are complex, and future studies are needed to further understand these findings.
“Moreover, our population-based study could not identify whether moderate alcohol or anthocyanins in red wine underlie the observed associations.”