The study published in the journal NeruoRegulation by Michelle Montopoli and others was conducted with support from The Hershey Company that provided chocolate products for the study and reviewed the manuscript prior to submission.
“Chocolate is indeed a stimulant and it activates the brain in a really special way,” said Stevens, a professor of psychological sciences at NAU. “It can increase brain characteristics of attention, and it also significantly affects blood pressure levels,” he said in a NAU release announcing the results of the study.
The study is the first to examine the acute effects of chocolate on attentional characteristics of the brain and the first-ever study of chocolate consumption performed using electroencephalography, or EEG technology. EEG studies take images of the brain while it is performing a cognitive task and measure the brain activity.
The researchers enlisted 122 participants between the ages of 18 and 25 to consume three chocolate treatments: higher (60%) cacao chocolate, low (0%) cacao chocolate or higher cacao chocolate + L-theanine.
In their study, researchers also included L-theanine, an amino acid extracted from green tea, because it has been shown in numerous animal and human studies to counteract the stimulating effects of caffeine and stressors. All the treatments were prepared by The Hershey Company and individually wrapped in 40 g squares of identical appearance and coded by content.
The results for the participants who consumed the 60% cacao chocolate showed that the brain was more alert and attentive after consumption. Their blood pressure also increased for a short time.
“A lot of us in the afternoon get a little fuzzy and can’t pay attention, particularly students, so we could have a higher cacao content chocolate bar and it would increase attention,” Stevens said. He added that a regular chocolate bar with high sugar and milk content won’t be as good, it’s the high-cacao content chocolate that can be found from most manufacturers that will have these effects.
L-theanine counteracts blood pressure spike
The most interesting results came from one of the control conditions, the 60% percent cacao chocolate which included L-theanine. This combination hasn’t been introduced to the market yet, but it is of interest to Hershey and the researchers.
“L-theanine is a really fascinating product that lowers blood pressure and produces what we call alpha waves in the brain that are very calm and peaceful,” Stevens said. “We thought that if chocolate acutely elevates blood pressure, and L-theanine lowers blood pressure, then maybe the L-theanine would counteract the short-term hypertensive effects of chocolate.”
For participants who consumed the high-cacao content chocolate with L-theanine, researchers recorded an immediate drop in blood pressure. “It’s remarkable. The potential here is for a heart healthy chocolate confection that contains a high level of cacao with L-theanine that is good for your heart, lowers blood pressure and helps you pay attention,” Stevens said.
Additional research warranted
For reasons of palatability and availability, the study utilized a dark chocolate confection containing only moderate amounts (60%) of cacao. The researchers admitted that this choice of chocolate confections was a “major limitation of this study” and quite likely resulted in the small effect sizes found in the analyses, even though the results reported were statistically significant.
Stevens said he hopes the results of this study will encourage manufacturers to investigate further and consider the health benefits of developing a chocolate bar made with high-cacao content and L-theanine.
“There are quite palatable chocolate preparations publicly available containing up to 90% cacao. Certainly this study should be replicated with a palatable chocolate confection containing higher percentages of cacao or increased concentrations of cacao bioactives to increase the magnitude of effect and to better understand which cacao constituents are predominantly responsible for these effects,” the authors concluded.
Published ‘Vol. 2, No. 1, pp. 3-28’ (2015), doi: 10.15540/nr.2.1.3
“The Acute Electrocortical and Blood Pressure Effects of Chocolate”
Authors: M. Montopoli, L. C. Stevens, C. Smith, G. Montopoli, S. Passino, S, Brown, L. Camou, K. Carson, S. Maaske, K. Knights, W. Gibson, J. Wu