A clinical trial has shown that in older people, a diet supplemented with cocoa flavanols– naturally occurring compounds found in cocoa beans—may improve performance on a specific memory task. The study is published on Monday 15 February in the journal Scientific Reports.
Researchers from Columbia University and New York University recruited 211 healthy people aged 50-75 for the trial, which lasted for 12 weeks.
At the start and end of the study, participants undertook a series of cognitive tests to assess their thinking and memory and a subset of the participants were given an MRI scan to measure blood flow in the brain.
During the trial, the participants were divided into four groups and given different levels of a supplement containing cocoa flavanols:
- Placebo (0 mg of Flavanols per day)
- low intake (260 mg)
- Medium intake (510 mg)
- high intake (770 mg).
Dr. Susan Kohlhass, Director of Research at Alzheimer’s Research UK, said:
“This small trial highlights some possible effect of flavanols found in cocoa beans over a short time period, but we’d need to see much longer, large-scale studies to fully understand whether a diet high in these flavanols could boost cognition in old age.
We also don’t know how meaningful the improvements measured in the tests used here would be for people in their daily lives.
“While the researchers found that by the end of the study, those on a high-flavanol diet performed better in a list-learning task compared to the placebo group, they did not find a relationship between flavanol intake and performance on two other cognitive tests, one of which was the primary endpoint for the study.
There was no effect of 12 weeks of flavanol supplementation on blood flow to the region of the brain the researchers had identified in advance of the study.
“This study didn’t look at dementia, and we can’t know from this research whether a diet high in cocoa would have any effect in either preventing or delaying the onset of the condition. The study used cocoa flavanol supplements provided to participants in capsule form.
While cocoa beans are the basis for chocolate, chocolates are not a reliable source of flavanol compounds and this study does not suggest that eating chocolate is good for our cognitive health.
“The study was partly supported by MARS, Inc. the company that produces Mars bars and a range of other chocolate products.
“Continued investment in research is crucial to find ways to protect the brain and reduce the risk of diseases that cause dementia. Although there’s currently no certain way to prevent dementia, research shows that a healthy lifestyle can help keep our brains health as we age. A healthy diet, regular exercise, not smoking, and keeping blood pressure and weight in check can all help lower the risk of dementia.
“We must do all we can to help people take action in support of their brain health. That’s why Alzheimer’s Research UK has launched the Think Brain Health campaign as an important first step.”
A healthy lifestyle is essential for the maintenance of normal cognitive functions both in young and elderly populations [1,2]. Cognitive abilities, particularly memory, attention, execution, and processing speed are progressively declined throughout the adult lifespan [3].
A complex interplay of genetic, endogenous, and environmental factors determine this process, with aging being the greatest risk factor for cognitive deterioration and dementia [4]. Increasing data suggest that lifestyle approaches such as nutrition may represent a promising opportunity to slow or prevent the progressive cognitive decline [5,6].
Indeed, there are numerous evidences that certain dietary patterns, as well as physical activity, can improve cognitive abilities and brain health across the human lifespan [7–9]. In this context, the role of plant-based dietary patterns and polyphenol-rich plant foods on either preventing or improving cognitive function has become an emerging area of investigation [10].
Considering this, recent reports have indicated that polyphenols could be associated with beneficial effects on cognitive and brain functions in young [11] and older adults [12]. Consistent findings from several studies confirm that these natural compounds can induce a positive effect on several cognitive processes, specifically executive function, attention, working memory, and processing speed [13].
Moreover, polyphenols can also exert neuroprotective functions due to their effectiveness against oxidative stress and inflammation as well as their capacity to modulate prosurvival or antiapoptotic signaling pathways [14]. Interestingly, better beneficial effects of polyphenols on brain plasticity biomarkers and on different cognitive functions have been found in young and middle-aged adults than in elderly [12,15], suggesting that young people can be an attractive population target to prevent onset of age-related diseases and cognitive decline. Indeed, cognitive function in young adults has great potential for intervention since brain tissue is less damaged and shows greater plasticity in response to new challenges.
In this context, cocoa is considered one of the best-known sources of dietary polyphenols, mainly monomeric flavanols such as (−)-epicatechin and (+)-catechin, as well as their dimers procyanidins B2 and B1 [16]. Furthermore, in recent years, evidences from human clinical studies have suggested that cocoa and cocoa-derived products consumption can be effective to improve general cognition and working memory, particularly among older population at risk or with cognitive decline [17,18].
Indeed, in a very recent systematic review [19], it has been indicated that memory and executive function can increase significantly after intake of intermediate doses of cocoa flavanols (CF) (500–750 mg/day). All these findings provide strong evidence supporting a potential beneficial role of cocoa to reduce cognitive decline and sustain cognitive abilities.
However, to date, the majority of studies have focused on the cognitive effects of cocoa flavanols in older people, while studies investigating the efficacy of cocoa on brain processes in young adults are more limited. Because young people have been identified as a particularly attractive population for cognitive interventions [12], it would be necessary to further investigate the impact of cocoa intake in young healthy adults as a potential preventative strategy to prevent cognitive decline related with age.
Therefore, the main objective of this study was to revise and update results from recent studies reporting beneficial effects of cocoa flavanols on brain function and cognitive response that might confirm in young humans most of the findings previously observed in adults and aged people.
To this end, this systematic review has focused on clinical trials investigating the effect of acute (cognition assessment is taken less than 4 h after cocoa flavanols intake) and chronic (cocoa flavanols are consumed at least for 5 days and cognition assessment is taken at least after overnight refrain from cocoa or other flavanol-rich foods consumption) cocoa intake on cognition in young adults (average age ≤ 25 years).
In this study, methodological aspects as well as the impact of cocoa intake on cardiovascular and cognitive endpoints are discussed. This review provides further support to the effect of cocoa on cognitive function and suggest for the first time that such benefits can be also observed in younger people.
Conclusions
The studies conducted so far on the potential of CF as neuroprotectors and neuromodulators have evidenced a certain efficiency on cognition and behavior, both in acute and in sub chronic (for several weeks) or chronic modes. The immediate effects can be achieved with a single dose of CF in appropriate dosages. The long-term effects most likely require chronic intake of flavanol-rich products. In general, flavanol active doses range from less than 100 mg to around 500 mg.
Most studies support the key role of NO and its effect on endothelial tissue to improve brain blood flow to increase cognitive function and attention. However, NO biological role in cognition is not solely as vasodilator, and thus we cannot assume that increasing the cerebral perfusion is uniquely responsible for the improved cognitive performance. Additionally, it has been reported that the enhancement of cognitive function in different intervention studies is related to an increase in blood BDNF levels, a protein associated with neuronal growth levels. In the brain, DBNF stimulates synaptic plasticity and neurogenesis and plays an important role in learning and memory functions.
For obvious reasons, most of the literature available on human antiaging research, including polyphenol interventions, refer the effect in population groups of elders or, in most of them, groups suffering from chronic diseases. Therefore, less is known about the effect of polyphenol interventions on cognitive processes in healthy young humans and children but some of them, especially those related to cocoa and its derivatives, indicate improved brain function following acute and/or chronic ingestion of cocoa flavanols.
Overall, most findings support the beneficial effect of cocoa flavanols on cognitive function and neuroplasticity in young adults, suggesting that the inclusion of cocoa powder or high-cocoa flavanols products may be a realistic and reasonable preventive approach on neurodegenerative diseases and cognitive decline. Furthermore, short and middle-term effects of daily cocoa intake may provide young adults with a better cognitive performance in verbal learning, memory, and attention favoring academic achievement. Nevertheless, the available evidence is very scarce and future studies are needed to increase the robustness of the results.
reference link: doi:10.3390/nu12123691
More information: Sloan, R.P., 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 11, 3837 (2021). doi.org/10.1038/s41598-021-83370-2
