Chocolate and Cognition: Researchers Show Diet Quality and Cocoa Antioxidants Improve Age-Related Memory Function
As the average age of the population increases globally, so too do the considerable societal and personal costs associated with a decline in cognitive performance during normal aging. Consequently, there is a growing amount of research focusing on the development of lifestyle and dietary approaches aimed at preventing or delaying the onset of age-related cognitive decline. The crux of this lies at the intersection of two main areas of interest and scientific inquiry: the unraveling of specific brain regions linked to cognitive aging and the impact of diet on cognitive performance.
Now, a team of researchers from the Columbia University Irving Medical Center in collaboration with scientists from Mars Edge, a business segment within Mars dedicated to nutrition, show that diet quality and intake of cocoa flavanols — plant-based, health-supporting antioxidants found in cocoa — may impact age-related memory function in normal cognitive aging. Their research, published in Scientific Reports, followed over 200 healthy adults aged 50-75 for 20 weeks to show that those with habitually lower diet quality were more likely to experience improved memory following increased flavanol intake. This improvement was found to be tied to activity in the hippocampus — the brain region linked to learning and memory.
These findings suggest that diet in general, and dietary flavanols in particular, may be associated with memory function of the aging hippocampus and normal cognitive decline. Dr. Hagen Schroeter, Chief Science Officer at Mars Edge, said, "This study builds on previous research looking at cognitive benefits of flavanol intake and provides encouraging evidence of the importance of nutrition, and support for the identification of possible dietary approaches to promote healthy cognitive function as we age."
A Cocoa-Inclined Clinical Study
Assessing the impact of diet on cognitive aging, Sloan and colleagues conducted a clinical study testing the effects of taking cocoa flavanols for 12 weeks, followed by an eight-week period in which the participants returned to their typical diet. Flavanols are bioactive compounds naturally present in foods — such as cocoa, grapes, berries, and pome fruits like apples and pears — that are widely investigated for their role in health and nutrition.
Throughout this, participants completed a series of tasks involving areas of the brain thought to be important in cognitive aging. A newly developed object-recognition task targeted the dentate gyrus, a specific region within the hippocampus previously indicated to be sensitive to flavanol interventions. Previously established list-learning and list-sorting tasks respectively targeted the hippocampus and prefrontal cortex, which is linked to complex cognition and decision making.
Also, the collaborative research team assessed the amount of fruits, vegetables, whole grains, and the balance of other foods in an individual’s diet. The team also measured a recently validated novel biomarker in blood, which allowed for an objective assessment of each participant’s typical flavanol intake.
Cocoa Flavanols Favor Fitter Memory
What Sloan and colleagues found was that at baseline, before the dietary flavanol intervention, participants with higher diet quality and higher habitual flavanol intake performed better on list-learning memory tests related to the hippocampus, reflective of episodic memory — the recollection of specific events, situations, and experiences. However, list-sorting memory performance related to the prefrontal cortex was not linked to a persons’ habitual diet quality or flavanol intake at baseline.
After the intervention, those consuming the highest dose of cocoa flavanols daily (770mg) — a 40 gram serving of chocolate (the size of a medium bar) provides 136 mg to 440 mg of flavanols depending on the brand — for 12 weeks performed significantly better in the list-learning task, compared to the group that didn’t take any cocoa supplement. The effects were seen even when participants’ age, sex, and level of education were accounted for. This further supports the interpretation that the flavanol intake was a driving factor for the observed memory improvements. Generally, those with lower diet quality were more likely to experience improved memory following the flavanol intervention. Eight weeks after stopping the flavanol intervention, list-learning performance returned to pre-intervention levels, a finding that also supports the relevance of flavanols in this context.
In contrast to the list-learning results, the prefrontal cortex-dependent task was unaffected by the flavanol intervention, consistent with the findings before treatment. Performance on the new object recognition task was not linked to diet quality and did not improve with flavanol intake. Analysis suggested this task may have been too difficult for older participants.
Can Cocoa Combat Cognitive Crashing?
"It was very interesting to find that participants with lower diet quality and lower flavanol intake in this study were more likely to experience the largest effects on memory,” said Professor Scott Small, Professor of Neurology at Columbia University, who led the study. “To think that if someone with such a diet, which represents more than 50% of US population, improved their habitual diet and flavanol intake, could potentially experience a jump in their memory and cognitive performance, is intriguing.”
“It will be very interesting to see if our findings could replicate at the scale of the population, which is why we are awaiting with great interest the outcomes of the cognitive assessments that are part of the Cocoa Supplement and Multivitamin Outcomes Study (COSMOS),” said Professor Small. COSMOS is being run by Brigham and Women’s Hospital, an affiliate of Harvard Medical School, and the Fred Hutchinson Cancer Research Center. Mars is providing funding for COSMOS and the cocoa flavanol test materials.
Replication of these findings at scale may allow for an evidence-based assessment at the population level of the utility of dietary flavanols to address the significant challenge of age-related cognitive decline in late life. However, it is worth noting that this study was focused on participants with normal cognitive function. So, the generalizability of these findings is limited and cannot be extended to patient populations with clinical manifestations of dementia or cognitive dysfunction. In this context, dietary flavanols may offer meaningful benefits to cognitive health, although further studies are needed.
Sloan RP, Wall M, Yeung LK, et al. Insights into the role of diet and dietary flavanols in cognitive aging: results of a randomized controlled trial. Sci Rep. 2021;11(1):3837. Published 2021 Feb 15. doi:10.1038/s41598-021-83370-2