Flavonoid Consumption and Its Relationship with Alzheimer's Disease

The role of diet in the development of Alzheimer's disease has become a popular topic in recent years. One study on this subject claimed that insufficient consumption of foods containing flavonoids increases the risk of Alzheimer's disease.

Alzheimer's disease is common worldwide and is also the most common cause of dementia. People who develop Alzheimer's disease experience changes in memory, thinking and behavior. Their ability to perform daily activities can deteriorate to a mild or severe degree. In individuals aged 65 and over, the incidence of dementia increases by a factor of 2 every 5 years.

There is currently no effective treatment for Alzheimer's disease. However, its onset can be delayed to some extent. The role of diet in the development of Alzheimer's disease has become a popular topic in recent years. One study on this subject claimed that insufficient consumption of foods containing flavonoids increases the risk of Alzheimer's disease. Flavonoids are powerful antioxidants that oxidize free radicals produced in the body or taken in from outside.

What Are the Types of Flavonoids, and Which Foods Contain Them?

There are 6 subtypes of flavonoids, which are found mainly in fruit and vegetables. The flavonoid subtypes and the foods richest in them are listed below:

• Flavonols: onions, broccoli, peaches, lettuce, tomatoes, red grapes, red wine
• Flavan 3-ols (catechins): strawberries, apples, blueberries, cocoa, purple grapes, red grapes, white tea, green tea, black tea
• Flavones: parsley, green peppers, celery, mint, chamomile
• Flavanones: lemons, oranges, limes, grapefruit
• Isoflavones: soy and soy products, broad beans
• Anthocyanins: strawberries, blackberries, blueberries, red wine, cranberries, and red and purple grapes are some examples.

Does Insufficient Flavonoid Consumption Increase Alzheimer's Risk?

Diets low in flavonoids are thought to increase the risk of Alzheimer's disease by causing a long-term decline in brain function.

American Journal of Clinical Nutrition published a study investigating the relationship between flavonoid consumption and Alzheimer's disease in 2,801 participants over 20 years. Flavonoid intake was assessed using food-consumption records completed by the participants every 4 years. In the study, consumption within 1 month of:

• 1 apple, 100 g of berries and 0 cups of tea was classified as “Low”,
• 750 g of berries, 7 apples and 19 cups of tea was classified as “High” flavonoid consumption.

The study found that 193 people developed dementia, including 158 with Alzheimer's disease. When the relationship between flavonoid consumption and dementia was examined:

• People following a low-flavonoid diet were observed to have a 2-4 times higher likelihood of developing dementia according to the observations.

When the relationship between different flavonoid types and dementia was examined:

• Low anthocyanin intake was found to increase dementia risk 4 times,
• while low flavonol intake was found to increase it 2 times.

- Related topic: What Is Dementia? Are Dementia and Alzheimer's Disease the Same Thing?

Neurology published another study involving 921 participants, which found that the group with the highest flavonoid consumption had a risk of developing Alzheimer's disease that was 48% lower according to the results.

Many risk factors can contribute to dementia, including older age, a family history of dementia, chronic disease and smoking. These findings therefore do not mean that everyone who follows a diet low in flavonoids will develop Alzheimer's disease.

In addition to foods rich in flavonoids, fish, olive oil, walnuts and other nuts such as hazelnuts are important for reducing Alzheimer's risk. For example, the MIND diet, whose name comes from the initials of “Mediterranean-DASH Intervention for Neurodegenerative Delay,” combines the Mediterranean and DASH diets. This eating pattern was developed to reduce the risk of neurological disease and promotes whole grains, legumes, leafy green vegetables, fruit, fish, red wine and nuts.

Summary and Commentary

An effective treatment for Alzheimer's disease has not yet been developed. However, as with many diseases, a healthy diet and a good lifestyle are important for protection against Alzheimer's disease. The Mediterranean diet has been shown in many studies to reduce the development of progressive neurological diseases such as Alzheimer's disease. A balanced, healthy eating pattern such as the Mediterranean diet can therefore increase your flavonoid intake, while regular exercise and a good social life can help improve your cognitive function.