A team of researchers led by Columbia University and Brigham and Women’s Hospital has recently discovered that a diet low in flavanols – a type of nutrients found in a variety of fruits, vegetables, and beverages such as tea, cocoa, or wine – plays a fundamental role in driving age-related memory loss. These findings suggest that the aging brain requires specific nutrients for optimal health in a similar way that the developing brain needs specific nutrients for proper development.
“The identification of nutrients critical for the proper development of an infant’s nervous system was a crowning achievement of 20th century nutrition science,” said senior author Scott Small, a professor of Neurology at Columbia.
“In this century, as we are living longer, research is starting to reveal that different nutrients are needed to fortify our aging minds. Our study, which relies on biomarkers of flavanol consumption, can be used as a template by other researchers to identify additional, necessary nutrients.”
The study builds on 15 years of research conducted at Small’s lab examining the relation between age-related memory loss and changes in the dentate gyrus – a region of the brain’s hippocampus that is vital for the formation of new memories. In a series of experiments on both mice and humans, Small and his colleagues discovered that flavanols improve function in the dentate gyrus by enhancing the growth of neurons and blood vessels.
The current study was designed to investigate the impact of flavanols in a much larger group, consisting of 3,500 healthy older adults randomly assigned to receive either a daily flavanol supplement or a placebo for three years.
At the beginning of the study, each participant had to complete a survey assessing the quality of their diet. Afterward, the individuals performed a series of web-based activities in their own homes to assess the types of short-term memories structured by the hippocampus. These tests were repeated each year.
Finally, over a third of the participants supplied urine samples in order for researchers to measure a biomarker for dietary flavanol levels to determine if these levels corresponded to performance on the cognitive tests and make sure the participants were sticking to their assigned regimen.
The analyses revealed that, after one year, participants who had initially reported consuming a poor diet with lower flavanol levels saw an increase in their memory scores by an average of 10.5 percent compared to the placebo group and 16 percent compared to their memory at baseline. Such improvements were sustained for at least two more years. However, in the case of participants who did not have a flavanol deficiency at the beginning of the study, no significant increase in memory scores was found after taking the supplement.
These findings, which are published in the journal Proceedings of the National Academy of Sciences, suggest that flavanol deficiency is a driver of age-related memory loss, although it is not yet clear what other factors are at play.
“We cannot yet definitively conclude that low dietary intake of flavanols alone causes poor memory performance, because we did not conduct the opposite experiment: depleting flavanol in people who are not deficient,” Small explained.
In future research, the scientists plan to confirm flavanols’ effect on the brain through a clinical trial aiming to restore flavanol levels in adults with severe flavanol deficiency.
“Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability. If some of this variance is partly due to differences in dietary consumption of flavanols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavanols when they’re in their 40s and 50s,” Small concluded.
Flavanols are a type of flavonoid, a class of compounds with antioxidant effects. Flavonoids are a diverse group of phytonutrients (plant chemicals) found in almost all fruits and vegetables. They are known for their health benefits, which are often attributed to their antioxidant, anti-inflammatory, and immune-boosting properties.
These are perhaps the best-known sources of flavanols. It’s important to note that the flavanol content can vary significantly, depending on the cocoa processing method. Dark chocolate and cocoa powders that have undergone minimal processing tend to have the highest flavanol content.
These fruits, especially their skins, are good sources of flavanols.
Both these teas are rich in a subclass of flavanols known as catechins.
Flavanols might improve cardiovascular health by reducing blood pressure and improving blood flow to the heart and brain. They can also help make blood platelets less sticky, reducing the risk of blood clots.
Some studies have found that flavanols can improve blood flow to the brain, potentially protecting against age-related cognitive decline.
Flavanols, like other antioxidants, can neutralize harmful free radicals, reducing the risk of cell damage and potentially the risk of certain types of cancer.
Some research suggests that flavanols can improve insulin sensitivity and blood sugar control.
Flavanols in cocoa may improve the structure and function of skin, protect against sun damage, and improve hydration and complexion.
However, it’s important to note that while the potential health benefits of flavanols are promising, many of the effects have been observed in laboratory studies or large-scale population studies, and further research, particularly in the form of randomized controlled trials, is needed to confirm these findings