Larry Stevens eats a piece of high-cacao content chocolate every afternoon, which is in part because he has developed a taste for the unsweetened dark chocolate. It’s also because research shows that it lowers blood pressure and his new study reveals that it improves attention, which is especially important when hitting that midday slump.
“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.”
The study, published in the journal NeuroRegulation and sponsored by the Hershey Company, 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.
Historically, chocolate has been recognized as a vasodilator, meaning that it widens blood vessels and lowers blood pressure in the long run, but chocolate also contains some powerful stimulants. Stevens said his team wanted to investigate if people who consume chocolate would see an immediate stimulant effect.
Stevens and his colleagues in the Department of Psychological Sciences performed the EEG study with 122 participants between the ages of 18 and 25 years old. The researchers examined the EEG levels and blood pressure effects of consuming a 60 percent cacao confection compared with five control conditions.
Michelle Montopoli, an NAU alumna and student at the time of the study, led the EEG testing phase which included measuring serving sizes of the samples based on participant weight and packaging them so the participants were blind to what they were tasting. Constance Smith, professor of psychological sciences, assisted with the physiological analyses.
The results for the participants who consumed the 60 percent 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.
The most interesting results came from one of the control conditions, a 60 percent cacao chocolate which included L-theanine, an amino acid found in green tea that acts as a relaxant. This combination hasn’t been introduced to the market yet, so you won’t find it on the candy aisle. 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.
Stevens 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.
“People don’t generally eat chocolate and think it’s going to be healthy for them,” Stevens said. He added that there is a possibility the millions of hypertension patients in the country could eat a bar of this heart healthy chocolate every afternoon and their blood pressure would drop into the normal range, and they would be more alert and attentive.
Patrick Hannon says
Larry, Enjoyed reading about this study! Good to hear that you are still very active at NAU.
Pat Hannon
ps Again thanks for loaning me the EEG instrumention back in the 1990s for my research in use of lighting in human alertness, vigilance.
Larry Stevens says
It’s great to hear from you Pat, and thank you for the very nice comments on the article. EEG studies are fascinating and the technology has improved considerably since the 1990s, particularly in the density of arrays, the portability of equipment, the breadth of analyses, and the capability of higher resolution cortical neuroimages generated from the surface EEG. Our article shows some of the latter for our chocolate participants. Best to you and I hope we get a chance to collaborate again some day.
Charles Main says
Good article on the benefits of chocolate. The best dark chocolate is 72 percent cacao.
Most health food stores sell it. Trader Joe’s has excellent variety of dark chocolates including the 72 dark variety. Thanks for the read.
Larry Stevens says
Thank you for your comments Charles. I hope you enjoyed the article. Fortunately there are many options available now in traditional and health food grocery stores for higher cacao chocolate confections that are palatable and offer the vascular and attentional benefits of cacao. I appreciate your awareness that, for the health benefits of chocolate, it is important to select a confection that is as high in cacao as is palatable for the consumer. Eat healthy and enjoy.
Dr.Pradhan says
Sir,
I would like to know about the adverse effects of emulsified fat present in the chocolate.Will it offset all the benefits?
Is there any particular percentage of cocoa that should be browsed for while buying the bar?Any particular brand that one needs to search for?Thanks,
Larry Stevens says
Dr. Pradhan, you present some interesting and important questions. First, with regard to the fat content of chocolate, cacao contains relatively high percentages of 3 types of fatty acids. One, Oleic Acid, actually is heart-healthy as a mono-unsaturated fat found in olive oil. The other 2 are saturated fats, Stearic Acid and Palmitic Acid. As you know, saturated fats are linked to elevations in LDL cholesterol and Palmitic Acid does have that effect, but it only represents about a third of the fats in cacao. Research on Stearic Acid indicates that it neither lowers nor raises LDL cholesterol. The net effect is that prolonged consumption of cocoa butter and/or chocolate containing all 3 of these fatty acids has a neutral effect on blood lipid levels (Steinberg et al., 2003). Furthermore, cacao is very high in anti-oxidants which retard the process of LDL oxidation and may actually help prevent arterial injury. Hollenberg et al. (2004) conclude that “provided total fat intake does not exceed the recommended levels, there is no reason to believe that consumption of chocolate would represent an increased risk to health . . . .” As a real-world example, let me refer you to the story of the Kuna Indians of Panama.
Regarding brands and percentages of cacao, the brand is less important than the percentage of cacao and the other constituents of the chocolate confection (sugars, milk solids, etc.) Virtually all companies make confections that vary in percent of cacao. See my comments to Charles above regarding percentages and palatability.
Thank you, Dr. Pradhan, for your questions and for your interest in our research in the Department of Psychological Sciences at Northern Arizona University.
Kira says
We’re supposed to expect unbiased results for a study on chocolate sponsored by Hershey? Hello- this isn’t good.
Of course they’re going to find that everyone should eat a chocolate bar and every day no less- and to assume it can treat people with hypertension? Wow.
I’m disappointed that the results of this would even be published.
Larry Stevens says
Kira, I can appreciate your distrust of a health study sponsored by a large international corporation, for I think that many of us quite naturally are suspicious of biased research outcomes on the behalf of corporate gain. However, I can assure you that The Hershey Company had no influence whatsoever on the outcomes of this study. Hershey’s role was only to respond affirmatively to my request to provide the chocolate confections used in the study and to quite astutely suggest the addition of the L-Theanine additive. My research team and myself developed the design, recruited and randomly assigned all 125 participants to the 6 treatment conditions, presented the 3 chocolate conditions in a double blind manner with both research assistants and participants completely unaware of which condition they were receiving, collected and analyzed all of the data, and prepared it for professional presentation and for publication, all without any input or supervision by The Hershey Company or any of its employees. Furthermore, no research participant nor research assistant nor myself received any remuneration, gifts, etc. for our involvement in this study. In fact, Hershey only knew of the outcomes when I presented them to representatives of the company after the study was completed. Consequently, I can unequivocally assure you that The Hershey Company had absolutely no influence on the outcomes of this study.
Furthermore, if you read the study (I would encourage you to do so by clicking on the hypertext “study” in the review above; you can freely download the entire PDF of the article.), you will see that the acute effect of the 60% cacao condition was to raise blood pressure, not to lower it. The introduction to the article reviews the literature which is very supportive of antihypertensive effects of long-term use of cacao confections. These studies were conducted across numerous laboratories using many different chocolate company products and accordingly seem free of bias. Our study was an acute effects study only, the first published EEG study of its kind. Additionally, the blood pressure lowering effects found in our study were not specific to chocolate but to L-Theanine, an extract of Green Tea which to my knowledge is not made by Hershey. Our study suggests that the sympathomimetics in cacao have a more immediate stimulatory effect on both the central and peripheral nervous systems, the latter effects of which can be offset by an L-Theanine additive, thus significantly reducing the immediate blood pressure elevating effects of cacao. We further suggest, from the literature review and not from the outcomes of our study, that longer-term vasodilation effects of the flavanols in cacao do have an antihypertensive effect. These biochemical effects would occur regardless of brand and more an effect of the concentration, cultivars, and processing of the cacao.
My research team and I remain very pleased with the design, the controls, the sample size, the analysis, the outcomes, and the presentation of this study. We believe that the implications of those outcomes are important and merit public exposure and that this study merits constructive replication across ours and other laboratories.
Thank you for your attention to this risk of bias in research, for we all need to be aware of this possibility as we carry out similar tests of the effects of food products, drugs, and other treatments on health concerns.
Ben says
Since chocolate contains caffeine, wouldn’t the psychostimulant effects and increase in blood pressure be similar to caffeine ingestion? Couldn’t these effects be from the stimulation of the adrenal glands and release of cortisol?
Would eating chocolate everyday build a tolerance since it contains caffeine?
Eating and apple can also increase energy and alertness without the toxic and sleep disturbing effects of caffeine. Try that on your next all night study session, afternoon slump or long distance drive.
How much was the grant from Hershey?
Larry Stevens says
Hello Ben,
Cacao contains very small amounts of caffeine, so small that they are unlikely to be responsible for the stimulant effects observed. However, cacao does contain rather sizable amounts of the sympathomimetics phenylethylamine (PEA) and theobromine, both of which tend to stimulate the release of catecholamines and lead to increased central and peripheral arousal. It is more likely that the CNS and PNS arousal effects we observed were due to these two constituents. To my knowledge, the development of tolerance to these substances in cacao has not been studied, so we don’t know how long these stimulant effects will persist with repeated consumption of cacao.
Certainly the sugars in fruit will increase arousal as well, but in different ways. I encourage you to read our article in NeuroRegulation regarding the effects of sugar relative to cacao by downloading the PDF from the “study” hypertext link in the NAU Online summary above.
Regarding the involvement of Hershey, let me refer you to my detailed answer to Kira’s query above.
And thank you for your interest in our chocolate research.
John May says
Hi, Larry,
One drawback for any sort of chocolate is the effect that it’s caffeen has on the lower hatch above the stomach: it relaxes it. Subsequently, that allows for gastroesophageal reflux disorder, which can come back to bite you. Is this not true, despite the quantities you mentioned above?
Larry Stevens says
Hello John,
Thank you for your interesting thoughts about the effects of caffeine on GERD and other reflux conditions and for your interest in our study. The jury is still out on the role of caffeine in reflux disorders, however when one considers the amount of caffeine in a cup of black coffee (100-200 mg) and the miniscule amount in a gram of 60% cacao chocolate in our study (0.63 mg), it would seem unlikely that higher cacao chocolate confections would contain sufficient caffeine to affect the lower esophageal sphincter. Having said that, the best course would be to try a small amount to determine the effects, and, of course, if one suffers from GERD to consult with one’s gastroenterologist before making any dietary changes.
I hope these comments help answer your questions.
Bret Clawson says
Did the subjects who consumed the 60% Cocoa which included L-theanine appreciate the same alertness benefits? Were you able to rule out the transient hypersensitiveness as the cause for the alertness?
John says
Well I have cacao powder in my porridge and a mug of matcha green tea so no need for the chocolate that contains both. Simple!))