How Dark Chocolate May Support Cognitive Efficiency and Performance

If you love dark chocolate, we have great news. Two recent studies by a group of researchers from Japan that caught our attention assessed the benefits of polyphenol-rich dark chocolate on cognitive function. One of the studies assessed its effects on cognitive performance, while the other assessed its effects on brain activity. Here’s what the studies showed about how cocoa polyphenols may support an energy-efficient use of cognitive resources.

Key Takeaways

• Cocoa polyphenols support performance in cognitively demanding tasks.
• Cocoa polyphenols support an efficient use of cognitive resources.
• Dark chocolate with high polyphenol content may reduce the energetic cost of brain activity during tasks with high cognitive effort. 

How Cocoa Polyphenols May Support an Efficient Use of Cognitive Resources

Dark chocolate is rich in polyphenols, particularly a type known as cocoa flavanols such as (-)-epicatechin, which are known to support vascular function. By promoting healthy vascular function, cocoa flavanols can also support blood flow to the brain. Healthy cerebral blood flow is fundamental for an efficient delivery of oxygen and nutrients, which is in turn is essential for the brain to be able to generate the energy it needs to function. In addition, cocoa polyphenols can also support healthy mitochondrial function and mitochondrial metabolic pathways that generate cell energy as ATP in several tissues. Therefore, in addition to promoting nutrient delivery, cocoa may also support nutrient utilization and a more efficient energy production, which may contribute to healthier brain function and cognitive performance. This is relevant because the brain requires high amounts of energy for its functions, particularly during cognitively demanding tasks. 

Accordingly, studies have shown that cocoa polyphenol consumption can support cognitive performance and that this benefit may be associated with healthier cerebral blood flow and oxygenation. Studies have also shown that brain activity in regions of the brain relevant to cognitive performance can be supported by even a single intake of polyphenol rich chocolate. 

To better understand the benefits of cocoa polyphenols on brain function and cognition, a Japanese research group carried out two recently published studies assessing the effects of polyphenol-rich dark chocolate on the cognitive function of healthy adults aged 30–49 years. One of the studies, published in the journal Helyon, reported the effects of dark chocolate on cognitive performance in tasks that demanded high cognitive effort, while the other, published in the journal Nutrients, reported the effects of dark chocolate on brain activity associated with the same effortful cognitive tasks. The studies aimed to compare the effects of dark chocolate with high polyphenol content (635.0 mg of cacao polyphenols) to those of dark chocolate with low polyphenol content (211.7 mg of cacao polyphenols). 

In both studies, after dark chocolate ingestion, participants had to perform two 15-min sessions (with a 10-min interval between them) of a complex cognitive task that required maintaining selective attention to less obvious stimuli and ignoring more obviously and automatically processed stimuli. The task was a variation of the Stroop task in which words for colors may be presented in the corresponding color or in a different color, but participants have to identify the color by reacting to the word, not the color of the word. In addition to selective attention, this task recruits executive functions such as response inhibition and behavioral conflict resolution, which demands significant cognitive effort and resources. In the brain activity study, fMRI was used to assess brain activation in areas associated with executive function during the two cognitive task sessions; fMRI measures brain activity by detecting changes in blood flow: when a brain area is in use, blood flow to that region increases to deliver oxygen and nutrients to support activity.

Dark chocolate consumption contributes to the maintenance of performance and concentration in demanding cognitive tasks.

In the cognitive task performance study, participants had similar reaction times to stimuli with high polyphenol content (HC chocolate) and low polyphenol content chocolate (LC chocolate) in both sessions of the effortful cognitive task. However, the percentage of correct responses decreased in the second session with LC chocolate, indicating poorer performance, but was maintained with HC chocolate consumption. This suggested that intake of HC chocolate helped to maintain cognitive performance and concentration during both sessions of the tasks that demanded high cognitive effort, unlike LC chocolate. 

In the brain activity study, participants’ brain activity in the second session was lower with HC chocolate but higher with LC chocolate, despite no significant changes being observed in the cognitive task performance, unlike in the performance study (the authors attributed this difference to the different postures in each study—sitting in the performance study and supine position in the fMRI study—and to the stressful head restraint in the fMRI study, as both factors are known to change cerebral blood flow and task-related activation in the brain). The lower activity with HC chocolate (i.e., lower blood flow to the activated areas) indicated that it may have promoted a more efficient use of cognitive resources and reduced the energetic cost of brain activity during effortful cognitive tasks. 

Tasks with a high cognitive load in executive functions increase activity in brain regions associated with those functions, i.e, those brain regions “work harder.” But when cognitive efficiency is increased, the consumption of cognitive resources decreases—neurons are able to do the same work with less energy expenditure. This is observed, for example, following cognitive training, which decreases brain activity in brain regions involved in executive functions during attentional tasks. 

Based on these two studies, the authors suggested that HC chocolate may promote a similar energy-saving effect on brain activity and support cognitive efficiency, which may manifest as a promotion of cognitive performance.

The Many Benefits of Polyphenols

This study highlights how the support of cerebral blood flow and metabolism by polyphenols may promote brain function and cognitive performance. But polyphenols have many other health benefits in the human body. 

Polyphenols support stress response and defense mechanisms such as antioxidant defenses. Polyphenols have the ability to enhance antioxidant defenses by promoting the activity of enzymes that remove ROS or synthesize cellular antioxidants. Dietary polyphenols also support gut health and may have prebiotic-like actions that support the abundance of health-promoting gut microbes such as Akkermansia muciniphila. Through these actions, polyphenols help to preserve healthy cell and tissue function, support the gut microbiome, and contribute to general health, including metabolic, cardiovascular, and brain health. 

In addition to cocoa, polyphenols can be found in fruits, vegetables, herbs, spices, nuts, whole cereals and grains, legumes, algae, extra virgin olive oil, coffee, green tea and black tea, and red wine. As you can tell from this list, they are naturally part of a healthy diet.

*These statements have not been evaluated by the Food and Drug Administration.  This product is not intended to diagnose, treat, cure, or prevent any disease.

Referenced articles:

Sasaki A, et al. The effects of dark chocolate on cognitive performance during cognitively demanding tasks: A randomized, single-blinded, crossover, dose-comparison study. Helyon 2024, 10(2): e24430. doi:10.1016/j.heliyon.2024.e24430

Sasaki A, et al. Cacao polyphenol-rich dark chocolate intake contributes to efficient brain activity during cognitive tasks: A randomized, single-blinded, crossover, dose-comparison fMRI study. Nutrients 2024, 16(1):41. doi:10.3390/nu16010041.