Evidence continues to mount that the family of plant compounds known as flavonoids can help slow or even halt the progression of Alzheimer’s disease and other forms of dementia.
Flavonoids are a family of chemicals that have been widely studied for a variety of health benefits. They are powerful antioxidants and occur in high concentrations in a variety of fruits and vegetables, particularly citrus fruits, berries, grapes, onions, parsley and legumes. Other good sources include tea (especially green and white), red wine, dark chocolate, ginkgo biloba and seabuckthorn.
For a long time, scientists believed that the powerful antioxidant properties of flavonoids – allowing them to scour damaging free radicals from the body – were behind their health effects. Alzheimer’s-related flavonoid research fell out of favor, however, when studies demonstrated that most flavonoids break down rapidly in the body and cannot cross the blood-brain barrier, and when tests with other antioxidants such as Vitamin E showed no benefit in dementia patients.
New research suggests that flavonoids may operate by a different mechanism entirely to provide benefit to patients with Alzheimer’s disease and other forms of dementia, however.
“There have been some intriguing epidemiological studies that the consumption of flavonoid-rich vegetables, fruit juices and red wine delays the onset of the disease,” said Robert Williams of Kings College London.
In a presentation to the summer meeting of the British Pharmacological Society in Edinburgh, Williams reported findings that the chemical epicatechin, in the catechin family of flavonoids, can reduce the symptoms of Alzheimer’s disease when taken orally.
“We have found that epicatechin protects brain cells from damage but through a mechanism unrelated to its antioxidant activity and shown in laboratory tests that it can also reduce some aspects of Alzheimer’s disease pathology,” Williams said. “This is interesting because epicatechin and its breakdown products are measurable in the bloodstream of humans for a number of hours after ingestion and it is one of the relatively few flavonoids known to access the brain suggesting it has the potential to be bioactive in humans.”
“Our findings support the general concept that dietary intake of flavonoid-rich foods or supplements could impact the development and progression of dementia,” Williams said, calling for more research.
“The challenge now is to identify the single flavonoid or combination of flavonoids that exert the most positive effects and to define the mechanisms of action and optimal quantity required before embarking on clinical trials to treat their effectiveness in dementia.”
Prior studies have found improved cognition in senior citizens who drink higher quantities of green tea, which is particularly high in flavonoids. Other studies have suggested that the catechins in green tea may reduce the cognitive effects of Alzheimer’s disease, including impaired memory and reference ability. Another study found that antioxidants in green tea reduced the oxidative stress in the brain caused by the buildup of beta-amyloid plaques.
Beta-amyloid proteins are strongly correlated with the progression of Alzheimer’s disease, although researchers remain divided over whether the proteins actually cause the disease or play some other role altogether.
Alzheimer’s disease is the most common form of dementia. It is an incurable, fatal and degenerative disease that leads to progressive loss of cognitive function. Approximately 15 to 20 million people suffer from the disease worldwide.
In addition to helping slow the progression of Alzheimer’s, research suggests that flavonoids may also help the body react to allergens, viruses and carcinogens. Catechins have been found in laboratory studies to reduce the risk of cancer, cardiovascular disease and diabetes, and to delay some of the signs of aging.
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