A new study found that higher intake of flavonoid-rich fruits in middle-aged adults was significantly associated with a lower risk of dementia, compared to a low intake of these fruits.
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A growing body of research suggests that consuming fruits rich in flavonoids can boost cognitive function and lower one’s risk of dementia. But there is little consensus on whether this potential health benefit varies by age.
Now, a new study led by the School of Public Health and Boston University Chobanian & Avedisian School of Medicine has found that higher overall intake of flavonoid-rich fruits during middle age, specifically, may decrease one’s risk of developing dementia in older age.
Published in the Journal of Prevention of Alzheimer’s Disease, the study found that middle-aged adults who consumed flavonoid-rich fruits reduced their chances of developing all-cause dementia by 44 percent, compared to middle-aged adults who consume a low amount of these fruits.
However, the study also found that certain individual fruits consumed in both midlife and late-life, or just in late-life, may provide some protection against dementia in older age. In midlife and late-life, apples and pears appeared to be especially health-protective, and in late-life, oranges, grapefruit, blueberries, peaches, apricots, or plums seemed to provide these cognitive benefits.
Flavonoids are naturally occurring compounds found in many plant-based foods, including vegetables, legumes, and herbs, in addition to fruits. The new results not only align with the possible benefits of a Mediterranean diet, which emphasizes plant-based foods and healthy fats, they also highlight tangible, practical adjustments that individuals can make to their daily diet to preserve their health and delay or prevent the onset of dementia.
“Our study findings help to better understand the timing of or when potential dietary interventions may be most beneficial to reducing dementia risk in late-life and promoting healthy brain aging,” says study senior and corresponding author Phillip Hwang, assistant professor of epidemiology. The study’s lead author is Chenglin Lyu, a bioinformaticist in the Department of Anatomy & Neurobiology at the Chobanian & Avedisian School of Medicine.
The study is among the first to examine potential differences in associations between flavonoid-rich fruit consumption in midlife and late-life and diagnoses of dementia. As the world population ages and more people become at risk of developing Alzheimer’s disease and related dementias (ADRD), this new data can play a vital role in the global fight to prevent or mitigate this loss in cognitive functioning, and the enormous physical, emotional, and financial toll that ADRD can take on individuals, families, and the healthcare system.
For the study, Hwang and colleagues from the Chobanian & Avedisian School of Medicine, Tufts University, Duke University School of Medicine, and Stanford University School of Medicine utilized data on midlife and late-life flavonoid-rich fruit consumption and dementia diagnoses among participants in the Framingham Heart Study (FHS), the longest-running heart disease study in the United States, which launched in 1948. The study is led by Boston University and the National Heart, Lung, and Blood Institute. The researchers focused on 2,790 participants in the FHS cohort that joined the study between 1971-1975, aged 42-59 years old for the midlife group, and 60-82 years old for the late-life group.
While the middle-aged participants ate fewer fruits on average than the older participants—about 11 servings per week, compared to 13 servings per week—consuming these fruits in younger ages appeared to produce significant reduction in dementia risk later in life, compared to low intake of these fruits. The researchers did not observe a similar association between high and low intake of these fruits among the late-life group.
Flavonoids are known for their antioxidant, anti-inflammatory, and antiviral properties, and the researchers surmise that the compounds’ effects on cognitive health may stem from their ability to combat inflammation and protect neurons from toxins. But the team cautions that more research is needed to confirm the new findings and understand the precise impact of flavonoids in the context of a person’s daily diet, particularly younger adults.
“Future studies should examine the relationship between midlife dietary patterns, such as the Mediterranean diet, DASH diet, or MIND diet, and dementia risk, along with other markers of brain aging,” Hwang says.
