Study connects flavonoid-rich foods and lower dementia risk

The investigation, which appears in the journal JAMA Network Open, concludes that increasing intakes of commonly consumed flavonoid-rich foods and drinks, such as tea, red wine, and berries, may lower 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,” said the paper’s authors.

“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.”

Led by Dr Amy Jennings from the School of Biological Sciences at Queen’s University, Belfast, the prospective, population-based cohort study included dietary data from 121,986 adults aged 40 to 70 years in the UK Biobank.

Out of the total participants, 882 had incident dementia. The Flavodiet score adherence and intake of flavonoid subclasses were taken from a touchscreen questionnaire and a series of physical and biological assessments.

Flavonoid-rich foods inked to 28% lower dementia risk

The main finding suggested that consuming six additional servings of flavonoid-rich foods per day, in particular berries, tea, and red wine, was associated with a 28% lower risk of dementia.

The findings were most noticeable in individuals with a high genetic risk as well as those with symptoms of depression.

“These results provide a clear public health message as they suggest that a simple measure such as increasing daily consumption of flavonoid-rich foods may lower dementia risk, especially in populations at high risk,” said Dr Jennings.

“Currently, there is no effective treatment for the disease so preventive interventions to improve health and quality of life, and reduce social and economic costs, should continue to be a major public health priority.”

A wealth of studies in this area have proposed a series of mechanisms explaining the neuroprotective influence of dietary flavonoids that include the reduction of neuroinflammation; and improving cerebrovascular blood flow.

Indeed, many flavonoid intermediates have been shown to cross the blood-brain barrier and mediate the microbiome-gut-brain axis.

Self-reported dietary assessments can include errors and bias

Despite the promise of these findings, the research team also acknowledged the investigation’s limitations that included the use of self-reported dietary assessments and its documented measurement errors and reporting biases.

Commenting on the study's use of self-reported dietary data, Dr Emma Derbyshire, a UK-based registered public health nutritionist, said: “It is always useful to use blood biomarkers alongside self-reported intakes to help validate results.

“Other studies on other populations would be beneficial. Randomised controlled trials would also be more effective in helping to pinpoint whether there is further meaning in these results.”

Red wine should be consumed in moderation

The research team added that despite the study’s prospective nature, they could not rule out reverse causation, whereby participants who developed dementia may have altered dietary preferences before the onset of symptoms. This, according to Dr Derbyshire, “could have potentially biased or skewed findings”.

Commenting on the meaning of the results, she said: “Obviously red wine should be consumed in moderation and be aligned with alcohol guidance advice of no more than 14 units a week.

“…Alcohol in any form should be consumed in moderation. It is more about the totality of the diet rather than any one specific component.”  

“It specifies that the greatest risk reduction was observed in participants consuming at least two of the following per day: 5 servings of tea, one serving of red wine, and 0.5 servings of berries, compared with those who did not achieve any of these intakes. So, tea seems to be the main provider of flavonoids in this instance.”