Low Flavanol Intake May Lead to Memory Loss
Looking for natural ways to protect your noggin from memory loss? Join the club! A recent study from the combined research teams at Columbia and Brigham and Women’s Hospital/Harvard discovered that a diet low in flavanols—those important nutrients in fruits and veggies—may lead to age-related memory loss.
The research showed that in older adults, flavanol consumption aligns with scores on tests that measure memory loss related to normal aging. Replacing these bioactive compounds in individuals over the age of 60 that are mildly deficient in flavanols enhances performance on these particular tests.
Adam Brickman, PhD, professor of neuropsychology at Columbia University Vagelos College of Physicians and Surgeons and co-leader of the study, suggests that "The improvement among study participants with low-flavanol diets was substantial and raises the possibility of using flavanol-rich diets or supplements to improve cognitive function in older adults."
His research also supports the theory that the aging brain needs specific nutrients to function optimally, similar to how the developing brain also needs specific nutrients for normal growth and development.
The study's senior author, Scott Small, MD, the Boris and Rose Katz Professor of Neurology at Columbia University Vagelos College of Physicians and Surgeons, recognizes that "The identification of nutrients critical for the proper development of an infant's nervous system was a crowning achievement of 20th century nutrition science."
Now we are living longer and research is beginning to show that various nutrients are necessary to fuel our aging minds. This study, which relies on biomarkers of flavanol intake, can be utilized as a template by other scientists to find additional, necessary nutrients.
Age-related memory loss associated with changes in the hippocampus
The new research adds to over 15 years of studies in Small’s lab connecting age-related memory loss to changes in an area of the brain’s hippocampus known as the dentate gyrus. This region is necessary for learning new memories. Flavanols improve function in this area of the brain.
Other studies done in mice showed that flavanols, especially epicatechin (found in green tea), enhanced memory by improving neuron growth and blood vessels in the hippocampus.
Smith’s team evaluated flavanol supplements in humans. One small study showed that the dentate gyrus is connected to cognitive aging. A second, bigger study found that flavanols improved memory by selectively acting on this region of the brain and had the most affect on those who started out with a low-quality diet.
The Columbia and Brigham and Women’s Hospital teams evaluated the effects of flavanols and multivitamins in COSMOS (Cocoa Supplements and Multivitamin Outcomes Study). The new study, called COSMOS-Web, was developed to evaluate the effect of flavanols in a bigger group and test whether flavanol deficiency resulted in cognitive aging in this area of the brain.
Study design
Over 3,500 healthy older adults were assigned randomly to receive a daily flavanol supplement (pill form) or a placebo for three years. The ‘real’ supplement had 500 mg of flavanols, of which 80 mg of epicatechins were included, the amount that adults should receive from food.
At the start of the study, all subjects did a survey that evaluated their diet quality, including foods with high amounts of flavanols. Subjects then did a series of web-based activities at home, designed and validated by Brickman, to evaluate the types of short-term memory controlled by the hippocampus. These evaluations were repeated after one, two, and three years. The majority of subjects identified themselves as non-Hispanic and white.
Over a third of the subjects also provided urine samples. This allowed the researchers to measure a dietary flavanol biomarker level, developed by co-study authors at Reading University in the UK, before and during the study. The biomarker provided the researchers with a more exact way to find if flavanol levels correlated to performance on the cognitive tests and monitor if participants were sticking to their assigned regimen (adherence was high throughout the study). Flavanol levels varied moderately, though no subjects were severely deficient in flavanols.
People with mild flavanol deficiency benefited from flavanol supplement
In the group taking the daily flavanol pill, memory scores increased slightly. The majority of subjects were already eating a nutritious diet high in flavanols.
At the end of the initial year of taking the flavanol pill, subjects that admitted to eating a poorer diet and had lower levels of flavanols at baseline had an increase in memory scores by an average of 10.5% when compared to those taking a placebo. This was increased by 16% compared to their baseline memory score. The improvement seen at one year was maintained for at least two more years based on annual cognitive testing.
The study results strongly suggest that a deficiency in flavanols could result in age-related memory loss. Flavanol intake was associated with memory scores and flavanol supplements enhanced memory in older adults who were flavanol deficient.
The results of this study align with a recent study that discovered that flavanol supplements didn’t improve memory in a group of individuals with a range of baseline flavanol levels. However, the other study failed to review the impact of flavanol supplements on those with low and high flavanol levels separately.
Both studies found that flavanols have no impact on individuals who aren’t deficient in flavanols, according to Small. The other study may not have used memory tests that evaluate memory processes in the hippocampus impacted by flavanols. The new study showed that flavanols only helped memory processes regulated by the hippocampus and didn’t improve memory modulated by other regions of the brain.
What’s next?
"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 says, adding that such an experiment might be considered unethical.
A clinical trial to restore levels of flavanols in those with severe deficiency would be the next step. "Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability," says Small. "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."
Below are the top foods to include in your diet to increase flavanol intake:
· Apples
· Green and black tea
· Blackberries, blueberries, strawberries, raspberries
· Citrus fruit
· Kale, spinach, and other leafy greens
· Beans and lentils
· Broccoli
· Cocoa
· Red wine in moderation
Lisa Andrews, MEd, RD, LD
Reference:
Adam M. Brickman, Lok-Kin Yeung, Daniel M. Alschuler, Javier I. Ottaviani, Gunter G. C. Kuhnle, Richard P. Sloan, Heike Luttmann-Gibson, Trisha Copeland, Hagen Schroeter, Howard D. Sesso, JoAnn E. Manson, Melanie Wall, Scott A. Small. Dietary flavanols restore hippocampal-dependent memory in older adults with lower diet quality and lower habitual flavanol consumption. Proceedings of the National Academy of Sciences, 2023; 120 (23) DOI: 10.1073/pnas.2216932120
