by Mounting research suggests that what you eat plays an important role in preventing dementia.
Greater adherence to the Mediterranean diet, for example, has been linked to a lower risk of cognitive disorders and Alzheimer’s disease. Diets rich in whole plant foods have been shown to offer the strongest protection against dementia in middle-aged and older adults.
Higher intakes of flavonoids, bioactive compounds found in fruits, vegetables and other plant foods, are also associated with a lower risk of dementia.
Now, a new observational study – the largest to date – supports the cognitive benefits of a flavonoid-rich diet.
According to the researchers, eating a diet with a high “flavodiet” score offers significant protection against dementia, especially in people at high genetic risk and those with hypertension or symptoms of depression.
What is known about the study, as well as which flavonoid-rich foods – and how many servings per day – may benefit the most.
Flavonoids and brain health
Flavonoids are a family of over 5,000 plant (phytochemical) compounds. They are categorized into subclasses based on their chemical structure, which affects their specific health properties.
Flavonoids are thought to protect brain cells by reducing inflammation, protecting against free radical damage, improving blood flow to the brain and preventing the harmful effects of beta-amyloid, sticky proteins that form plaques and destroy brain cells.
The latest research
The study, published online September 18 in the journal JAMA Network Open, investigated the relationship between daily flavonoid intake and dementia risk among 121,986 male and female participants in the UK Biobank, an ongoing study of more than 500,000 adults across of the United Kingdom.
Participants, aged 40 to 70, provided demographic, health and lifestyle information through questionnaires and oral interviews. Genetic testing was performed to calculate participants’ genetic risk scores for dementia.
Dietary data were collected twice during the study. A unique “flavodiet” score was calculated for each participant by adding the daily intake of the main contributors to each flavonoid subclass: tea (black and green), red wine, apples, berries, grapes, oranges, grapefruit, sweet peppers, onions and dark chocolate.
During a follow-up period of 9.4 years, 882 participants had developed dementia.
Overall, compared with the highest and lowest flavodiet score, eating an additional six daily servings of flavonoid-rich foods was associated with a 28 percent lower risk of developing dementia in all participants.
The results also showed that a high flavonoid diet was protective against dementia in people with a non-modifiable risk factor (genetics) and those with modifiable risk factors (depression or hypertension).
When the researchers specifically considered participants at high genetic risk, eating six additional servings per day of flavonoid-rich foods was linked to a 43 percent lower risk of dementia.
Among those who reported symptoms of depression at the start of the study, eating six extra flavonoid-rich foods a day was associated with a 48 percent lower risk. And for participants with hypertension, the risk of dementia was reduced by 30 percent for those who ate six additional servings of flavonoid-rich food per day.
Study results on tea, berries and red wine
The greatest protection was seen in participants who consumed at least two of the following each day: five 6.5-ounce servings of black or green tea, one 6-ounce serving of red wine and half a serving of berries ( two or three tablespoons).
This was associated with a 38 percent lower risk of dementia compared to participants who did not meet any of these ideal intakes, defined as the average daily intake of participants who were the highest consumers of these foods.
The researchers’ analysis of flavonoid subclasses supported this finding. The subclasses of anthocyanins, flavan-3-ols and flavones, of which tea, red wine and berries are among the participants’ favourites, showed the strongest protection against dementia.
Current data on alcohol intake and risk of dementia are unclear. Canada’s current health guideline is to drink no more than two standard drinks per week at minimal or low risk of negative health consequences. One standard drink is 5 ounces of wine, 12 ounces of 5 percent beer or 1.5 ounces of 80-proof spirits.
Finding flavonoids
According to the researchers, the results of the study “showed the benefits of eating a variety of flavonoid-rich foods to lower the risk of dementia.”
Include different flavonoid subclasses in your regular diet. These include anthocyanins (berries, red grapes, cherries, red cabbage), flavan-3-ols (green tea, black tea, cocoa), flavonols (onion, kale, arugula, broccoli), flavanones (citrus fruits), flavones (bell pepper, celery, parsley) and isoflavones (soybeans, tofu, chickpeas, peanuts).
Leslie Beck, a private practice dietitian based in Toronto, is the director of food and nutrition at Medcan. Follow her on X @LeslieBeckRD
