Flavonoids? These are very common molecules among plants, which are responsible in particular for the bright colors of flowers, fruits and vegetables. They are also known for their antioxidant properties. A new American study confirms that the consumption of foods and drinks rich in flavonoids – in particular berries, apples and tea – decreases the risk of developing Alzheimer's disease or other forms of dementia.
Several previous studies have already proven that diet has a definite impact on dementia. However, most of them were based on data collected over short periods of time. This new study, conducted by US researchers from the Center for Research on Human Diet and Aging, followed a sample of older people for 20 years! “Our study provides a preview how diet over time might be related to a person's cognitive decline, as we were able to look at flavonoid intake for many years before participants were diagnosed with dementia “says Paul Jacques, professional epidemiologist and lead author of the study.
Alzheimer's disease is the most common form of dementia (it accounts for about 60-80% of cases). Currently, nearly 6 million Americans are living with this disease, and by 2050, that number is expected to reach 14 million. In the absence of effective drugs to treat or alleviate the disease, preventive measures are currently the only way to, if not block, at least postpone its appearance and slow down its progression. Prevention through diet is one of the avenues to explore.
Flavonoids are natural substances found in plants, including fruits and vegetables such as pears, apples, berries, citrus fruits, onions, and plant-based beverages such as tea, beer, and red wine . Dark chocolate is also an excellent source of flavonoids. Not only do these molecules give nature its pretty colors, especially in spring, but they are very beneficial for health. Scientific studies have revealed that their antioxidant properties give them protective properties against cardiovascular disease and cancer.
Their protective effect does not seem to stop there:flavonoids also have a protective effect against Alzheimer's disease and other related dementias. The team behind the study followed 2,800 people, aged 50 and over, over 20 years to find out how their diet influenced the development of these diseases, diagnosed later in life. life. Result:a low intake of three types of flavonoids in particular was linked to a higher risk of dementia compared to the highest intake of these substances. The three types of flavonoids identified are:
– flavonols (known to be the most effective antioxidants), found in particular in red fruits (strawberries, blackberries, raspberries), tomatoes, apples, pears, spinach, cauliflower, cocoa, beer and red wine;
– anthocyanins , which is also found in red fruits (cherries, blackberries and blueberries), but also in black grapes and eggplant for example;
– flavonoid polymers , which are present in apples, pears and tea.
Specifically, scientists have determined that a low intake of flavonols and flavonoid polymers is associated with a twice as high risk of developing dementia (Alzheimer's or related disease). Worse still:a low consumption of anthocyanins quadruples the risk of developing such a disease!
A “low” intake corresponds approximately to the consumption, per month, of an apple and a half (source of flavonols), but no berries (source of anthocyanins) or tea (source of polymers). Conversely, an intake considered “high” is equivalent to the monthly consumption of approximately 7.5 cups of blueberries (the fruit, not the flower!) or strawberries, 8 apples or pears and 19 cups of tea. A diet that must be adopted a priori if you want to put the odds on your side:“Tea, especially green tea, and berries are good sources of flavonoids “, underlines Esra Shishtar, lead author of the study. According to her, a cup of tea a day or a few berries two or three times a week would be enough to keep her flavonoid intake at a satisfactory level.
In concrete terms, to measure long-term flavonoid intake, the research team used dietary questionnaires, completed by participants during medical examinations carried out approximately every four years. To increase the likelihood that the information provided was accurate, the researchers excluded questionnaires from the years following the diagnosis of dementia, assuming that because cognitive status had declined, eating behavior may have changed and the questionnaires food items were more likely to be inaccurate. At the start of the study, none of the participants had any signs of dementia.
Obviously, the researchers are aware of the fact that the use of self-reported dietary data through questionnaires can be a source of errors (due to the effort of memory that this requires on the part of the participants). In addition, factors such as education level, smoking status, physical activity, body mass index, and overall diet quality of participants may have influenced the results. However, the researchers took these factors into account in their statistical analysis. In any case, the effect of flavonoids on health is proven and their consumption - even if no real causal link has been established with Alzheimer's disease - can only be beneficial for the body, several levels.
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The researchers point out that it's never too late to adopt a healthier diet. At 50 – the average age of study participants, from which the data began to be analyzed – there is still time to change your eating habits to evolve towards a more reasoned diet:"The risk of dementia really starts to increase from the age of 70, and the take-home message is that when you approach 50 or just beyond, you should start thinking about a healthier diet for your brain if you don't have it already done », insists Paul Jacques.
