Flavanols and the Hippocampus


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The importance of diet for a developing brain in adolescence is often well recognized. It is widely understood that children need nutrient-rich sources of foods, such as fruits and vegetables among other quality foods, to support their growth and development. However, the role of diet for the health of the brain in our older years often gets overlooked. Similarly to a developing brain, the brain needs extra support and attention to promote healthy neurological function well into advanced age. Diet plays a key factor in brain health, so eating the right foods to boost cognitive health is essential.

“Similarly to a developing brain, the brain needs extra support and attention to promote healthy neurological function.”

As we age, our cognitive abilities, including memory, begin to decline in most people. This common occurrence in older adults is known as “cognitive aging” and can bring about mild memory loss and other cognitive impairments. The symptoms of cognitive aging may not be as disruptive to one’s livelihood as more severe neurodegenerative diseases, such as dementia, but it can still make life more challenging and become disruptive to one’s daily routine.

While it is inevitable that we all age, it possible to significantly slow down the process of cognitive aging and lower the risk of impairments such as memory loss. According to a study
by Adam Brickman and coinvestigators at the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Vagelos College of Physicians and Surgeons, Columbia University, New York and published in the Proceedings of the National Academy of Sciences (PNAS), the foods we are eating play a significant role in the health of an aging brain. This study, “Dietary flavanols restore hippocampal-dependent memory in older adults with lower diet quality and lower habitual flavanol consumption,” is a culmination of 15 years of research providing evidence of the significant connection between the dietary consumption of flavanols and age-related memory changes. Flavanols are-plant derived phytochemicals found in fruits, vegetables, tea, and cocoa. They belong to the family of Flavonoids, the largest group of molecules within the polyphenols category. They have antioxidant properties when tested in cell cultures and are known to support cardiovascular and brain health as well as the growth of new brain cells.

This study builds on the previous culmination of research of Scott A. Small MD, Director of the Alzheimer’s Disease Research Center at Columbia University, who found that age-related cognitive decline was related to changes in the dentate gyrus, a region of the hippocampus that plays a major role in memory formation, in particular in the initial step of memory encoding. The hippocampus plays a major role in learning and memory. Additional research also found that flavanols support the formation of new blood vessels, enhance the vasodilatory effect of nitric oxide, along with neurogenesis specifically in the hippocampus region of the brain.

““…age-related cognitive decline was related to changes in the dentate gyrus, a region of the hippocampus that plays a major role in memory formation.”

Based on brain imaging studies with MRI, the flavanols selectively improved the function of the dentate gyrus by increasing global blood flow and capillary density. Researchers found that the flavanols had the greatest impact on those who previously had a poor diet. This outcome led for researchers to further question if the benefits that dietary consumption of flavanols has on memory are affected by the quality of their habitual diet.

In order to test this hypothesis, the researchers utilized data from 3,562 adult participants from the COSMOS study to understand the impact of flavanols on memory. Participants were randomly assigned to a 3-year intervention of flavanol consumption or a placebo. If assigned the flavanols, they were given 500 mg of cocoa flavanols per day.

At the beginning of the study, participants were initially tested on the quality of their diet using the alternative Healthy Eating Index along with recording biomarkers of flavanol intake in 1,361 of the participants. This subset group of participants provided urine samples to determine biomarkers of flavanol intake. This helped to ensure a more accurate understanding as to whether the flavanol intake had a significant impact on the memory scores when participants were being tested. It also served as confirmation as to if the participants were following the protocol for the correct supplemental dosage.

Following the assessment of diet, participants were then given a cognitive assessment designed to test memory. They were reassigned to take this memory test following year one, two, and three of flavanol intake. The researchers found improvements in the memory scores of all participants, however those who already had a healthy diet rich in flavanols (from consumption of fruits, vegetables, tea, and cocoa) showed only slight improvements.

The group that showed the most significant improvement in their memory scores from taking the flavanol supplement were those who originally had a poor-quality diet and a lower baseline of flavanols, a large percentage of the US population. With the annual testing, these results remained consistent throughout the three-year process demonstrating the significant effect that flavanols can have on memory. The findings of this study conclude that a deficiency in flavanols is a major risk factor of cognitive aging. While supplementing with flavanols was shown to not have such an effect in those who do not have a flavanol deficiency, ensuring that an individual does not have a lack of flavanols is essential to the support of the health of the brain in later years.

““The findings of this study conclude that a deficiency in flavanols is a major risk factor of cognitive aging.”

Just as the developing brain requires specific nutrients for optimal function, so does the aging brain in older adults. By consuming a diet rich in flavanols, it is possible to delay or slow cognitive aging. Since the average human lifespan and the percentage of centenarians in the world has been continuously increasing over the past 50 years, it is critical that we begin to understand the proper precautions to take to optimize wellbeing in our later years and increase not only our lifespan but the healthspan.

Finally, the observation that flavonol supplementation primarily benefited individuals with low flavonol levels suggesting insufficient consumption of fruits and vegetable, supplementation is an important part of the study, and this information may be applicable to other dietary supplements as well. If you stick to a healthy diet and lifestyle, and if you are in an age group that does have an extra need for such supplements, you probably are wasting your money on an expensive placebo. This extensive amount of research provides strong evidence of the importance of flavanols for brain health based on the recorded biomarkers, laying the way for future researchers to discover other essential nutrients for a healthy aging brain.

Amanda Johnson is a recent graduate from the University of Southern California where she received her degree in Psychology. In addition to her university studies, she earned her Integrative Nutrition Health Coach certification from the Institute of Integrative Nutrition (IIN).

This article was reviewed and approved by Emeran Mayer, MD