Currently, there are more than 50 million Americans aged 65 years or more, and that is projected to more than double by 2060. A consequence of this increase in older adults is the escalation of age-related diseases. Alzheimer’s disease (AD) and related dementias, a group of symptoms in which there is progressive deterioration in cognitive function severe enough to interfere with a person’s daily living activities, are regarded as among the most significant public health challenges largely affecting adults of this age.
AD is the most common form of dementia, making up ∼60–80% of dementia cases. Currently, 5.8 million Americans are living with AD, and by 2050 that is projected to escalate to 14 million.
A new study has shown that low intake of flavonoid-rich foods is linked to a higher Alzheimer’s risk over 20 years. Older adults who consumed small amounts of flavonoid-rich foods, such as berries, apples and tea, were 2 to 4 times more likely to develop Alzheimer’s disease and related dementias over 20 years, compared with people who consumed more of those items, according to the study.
The researchers studied the long-term relationship between eating foods containing flavonoids and the risk of Alzheimer’s disease and Alzheimer’s related dementias (ADRD). For this they included in the study 2,800 people aged 50 and older.
Flavonoids are natural substances found in plants, including fruits and vegetables such as pears, apples, berries, onions, and plant-based beverages like tea and wine. Flavonoids are associated with various health benefits, including reduced inflammation. Dark chocolate is another source of flavonoids.
The research team determined that low intake of three flavonoid types was linked to higher risk of dementia when compared to the highest intake. Specifically:
- Low intake of flavonols (apples, pears and tea) was associated with twice the risk of developing ADRD.
- Low intake of anthocyanins (blueberries, strawberries, and red wine) was associated with a four-fold risk of developing ADRD.
- Low intake of flavonoid polymers (apples, pears, and tea) was associated with twice the risk of developing ADRD.
The results were similar for Alzheimer’s disease.
The researchers said that their study can give us a picture of how diet over time might be related to a person’s cognitive decline. They analyzed 6 types of flavonoids and compared long-term intake levels with the number of AD and ADRD diagnoses later in life. They found that low intake of 3 flavonoid types was linked to higher risk of dementia when compared to the highest intake. Some examples are:
- Low intake was equal to no berries (anthocyanins) per month, roughly one and a half apples per month (flavonols), and no tea (flavonoid polymers).
- High intake was equal to roughly 7.5 cups of blueberries or strawberries (anthocyanins) per month, 8 apples and pears per month (flavonols) and 19 cups of tea per month (flavonoid polymers).
Esra Shishtar, first author of the article said that: “When we look at the study results, we see that the people who may benefit the most from consuming more flavonoids are people at the lowest levels of intake, and it doesn’t take much to improve levels. A cup of tea a day or some berries two or three times a week would be adequate.”
She also emphasizes that 50, the approximate age at which data was first analyzed for participants, is not too late to make positive dietary changes, because the risk of dementia really starts to increase over age 70 and that when you are approaching 50, you should start thinking about having a healthier diet if you haven’t already.
Tufts University, Health Sciences Campus. “More berries, apples and tea may have protective benefits against Alzheimer’s: Study shows low intake of flavonoid-rich foods linked with higher Alzheimer’s risk over 20 years.” ScienceDaily. ScienceDaily, 5 May 2020.
Paul F Jacques, Rhoda Au, Jeffrey B Blumberg, Gail T Rogers, Esra Shishtar. Long-term dietary flavonoid intake and risk of Alzheimer disease and related dementias in the Framingham Offspring Cohort. The American Journal of Clinical Nutrition, 2020