New study links flavonol-full foods to better memory in old age
Susan C. Olmstead
Another reason to eat well: A new study shows that eating certain fruits and vegetables—as well as chocolate—may slow cognitive decline in old age. The study investigated the effects of foods containing flavonol, which occurs naturally in certain plants.
According to the new study—from the Rush Institute for Healthy Aging at Rush University Medical Center in Chicago and published in the Nov. 22 online issue of Neurology—older people who ate or drank more flavonol-rich foods experienced a slower rate of memory decline.
To look into flavonol’s benefits, researchers followed 961 participants of the Rush Memory and Aging Project, a group of Chicago residents whose average age was 81, for an average of seven years.
They measured how the participants’ flavonol intake affected their memory, testing their global cognition, episodic memory, semantic memory, visuospatial ability, perceptual speed, and working memory.
The participants took annual standardized tests to measure these cognitive functions and also completed food frequency questionnaires.
The American Academy of Neurology (which publishes the journal Neurology) reported that after the researchers adjusted for other factors that could affect the rate of memory decline (such as age, sex, and smoking), they found that the cognitive score of people who had the highest intake of flavonols declined at a rate of 0.4 units per decade more slowly than people who had the lowest intake.
In other words, those subjects who consumed the highest level of flavonols—an average of about seven servings of dark leafy greens per week—had a 32 percent decrease in the rate of cognitive decline compared to the group that ate the least amount of flavonols, study author Dr. Thomas M. Holland told The Epoch Times.
“It’s exciting that our study shows making specific diet choices may lead to a slower rate of cognitive decline,” Holland said in a statement. “Something as simple as eating more fruits and vegetables and drinking more tea is an easy way for people to take an active role in maintaining their brain health.”
Holland’s work contributes to the ever-growing body of evidence showing “what we eat matters, and a diet that’s diverse in fruits and vegetables is critical for cognitive and physical functioning,” he said.
Flavonoids “help in preventing premature aging and deterioration of brain function, which is related to Alzheimer’s disease and dementia,” the researchers wrote in a review article published in the Iranian Journal of Basic Medical Sciences.
“Degenerative diseases and premature aging are closely associated with oxidative stress produced by the free radicals in the body,” they wrote.
So it just makes sense that foods that lower oxidative stress and neutralize harmful free radicals—that is, antioxidant foods—would fight diseases and slow aging.
After reviewing the evidence, the Iranian group called flavonoid-rich foods “the superfoods of the millennium.”
In Greece, researchers examining the effects of flavonoids on brain health found that flavonoids “enhance cognitive function at a behavioral level and attenuate cognitive decline promoted by brain disorders.” Their paper in the journal Biomedicine & Pharmacotherapy asserted that flavonoids “seem to have the ability to prevent or even reverse cognitive-related deficits by numerous mechanisms.”
They noted that about 5,000 flavonoids have been identified so far and can be divided into six groups: flavones, isoflavones, flavanones, flavonols, flavanols (also called flavan-3-ols), and anthocyanidins.
Foods With Flavonoids, Flavonols
The American Institute for Cancer Research has a list of flavonoid-rich foods on its site Flavonoids in Your Food: Here’s where to get them, featuring:
- Vegetables including onions, broccoli, asparagus, celery, leafy greens, kale, and tomatoes
- Herbs and spices including parsley and oregano
- Fruits including citrus fruits, berries, grapes, cherries, and peaches
- Beverages including black tea, green tea, white tea, and soy milk
The Micronutrient Information Center of the Linus Pauling Institute at Oregon State University features a more detailed list of flavonoid food sources on its site. Foods listed as rich in flavonol (the compound studied in the new Chicago study) include blueberries, broccoli, green chili peppers, cowpeas (black-eyed peas), kale, red onions, parsley, rocket (arugula), scallions, spinach, black and green tea, and watercress.
Organic, Responsibly Farmed Food May Be Better
According to the Mayo Clinic and other sources, organic foods may have more flavonoids than conventionally grown foods.
A meta-analysis of 343 peer-reviewed publications that appeared in the British Journal of Nutrition in 2014 reported that concentrations of flavonols in organic crops were 50 percent higher than in conventionally grown crops. This was in addition to the finding that pesticide residue was four times higher in nonorganic crops.
A six-year investigation published in 2017 in the American Chemical Society’s Journal of Agricultural and Food Chemistry found that flavonoid levels and antioxidant activity in onions grown in organic soil were higher than in conventional onions.
Interestingly, the investigators also found that weather conditions, including temperature and rainfall, also factored in flavonoid content, regardless of whether foods were grown under organic conditions.
Holland also noted that several factors dictate the concentration of flavonoids in foods, whether organically or conventionally grown. Sun exposure, soil composition, timing of harvest, and even altitude can all have an effect.
“There’s so much variability with regard to foods,” he said, explaining that sun exposure is vital.
If nonorganic crops are appropriately placed for maximum sun exposure, they could have a similar concentration of flavonoids as organic crops, he said, so farming technique matters.
Never Too Early—or Late
More good news about flavonoids and cognition: It’s never too early or too late to start making healthy lifestyle changes, especially when it comes to diet, according to Holland.
“We know that changes in the brain, i.e. accumulation of amyloid plaques and hyperphosphorylated tau protein or neurofibrillary tangles, start around 10–20 years before the onset of the easily detectable clinical signs and symptoms of cognitive changes. This means individuals may have Alzheimer’s neuropathology 10–20 years before cognitive decline is detected clinically.”
That means that waiting until symptoms show up isn’t the wisest course of action when improvements in diet can have a meaningful impact on the risk of dementia. Just one more reason to eat well and enjoy the benefits of natural nutrition.