Indulging in Happiness: The Mood-Boosting Potential of Dark Chocolate
Dark chocolate is associated with a number of health benefits related to the antioxidants it contains, including its effect on our mood (like we needed another reason to love chocolate!).
This article will break down a recent study by Shin et al. (2022) that explores “consumption of 85% cocoa dark chocolate improves mood in association with gut microbial changes in healthy adults: a randomised controlled trial” (1, 2).
What Was The Study Investigating?
This study was exploring whether different types of dark chocolate (70% and 85% cocoa content) have a positive impact on gut bacteria that may lead to improvements in mood. This connection between gut bacteria and our mood is related to the 2-way connection between our brain and our gut which is called the gut-brain axis.
Study Methods
This study was a single-blind randomised controlled trial* that included 48 men and women from Seoul National University (South Korea) in 2017.
*A randomised controlled trial (RCT) is a study where participants are divided at random between treatment groups or a control group, the control group is used to compare the outcomes of the treatments or experiment. If participants don’t know which group they are in this is called a single-blind RCT. If neither participants nor the researchers know which groups participants are in (to reduce the risk of bias) this is called a double-blinded RCT. This type of study is considered the gold standard for clinical trials.
Study participants:
were healthy adults between 20 and 30 years old
ate sweets like chocolate and cake less than twice per day
had no history of diabetes or gastrointestinal tract surgery or disease
had not used antibiotics within 3 months prior to the study or prebiotics/probiotics within 6 months of the study
had low depression scores
Participants were randomly divided into one of 3 groups:
control group
group consuming 10g of 85% cocoa chocolate x 3 per day for 3 weeks
group consuming 10g of 70% cocoa chocolate x 3 per day for 3 weeks
The main outcomes measured at the beginning of the study and after 3 weeks were gut microbiota and mood. The gut microbiome was assessed by analysing the DNA of bacteria in stool samples and a technique called 16s rRNA gene sequencing. The mood was measured using psychological tools the Positive and Negative Affect Schedule and the Beck Depression Inventory.
Body composition (weight, muscle mass, fat mass, BMI, and body fat per cent) and dietary intake using a 3-day food diary were also measured at these time points.
What Did They Find?
There were no significant differences between the groups at the beginning of the study in terms of body composition or nutritional intake. This makes comparisons between groups more accurate. Unsurprisingly in a study about eating chocolate, nobody dropped out and compliance with consuming the chocolate was high!
Eating dark chocolate was not found to significantly impact a positive mood state. But consuming 85% cocoa chocolate was significantly associated with a reduction in negative mood.
Interestingly, the diversity of gut bacteria also significantly increased in the 85% dark chocolate group according to one of the two gut diversity calculations that the researchers used.
Negative mood was found to have a negative relationship with gut diversity. This means that as the negative mood score increased, gut diversity decreased (i.e. negative mood was linked with less gut diversity).
What Does This Mean?
This study suggests that consuming 85% dark chocolate has a prebiotic effect by promoting better diversity and balance of the gut microbiome. It also found that this positive change in the gut may improve mood, as negative mood scores reduced when this dark chocolate was consumed and as gut diversity improved.
Like all studies, there are limitations to bear in mind with this study, such as:
it only included 48 participants
participants in the control group knew which group they were in as they weren’t given any chocolate to consume (although the researchers didn’t know who was in which group)
mood scores are based on self-reported information (which isn’t always accurate even when robust questionnaires are used)
This isn’t the first study to have found dark chocolate to be associated with improvements in mood. For example, a large survey from the US in 2019 found a significantly lower risk of symptoms of depression in those who consumed higher amounts of dark chocolate (3). Similarly, a study that involved consuming a dark chocolate drink for 30 days found significant improvements in feeling calm and content (4).
One important difference between this study and previous research is that participants consumed the chocolate under everyday conditions rather than in a more sterile lab environment.
Other studies have also found that increased gut diversity is linked with better mental health (5, 6, 7). This may be related to the impact of gut bacteria on the immune system, inflammation and how the gut and brain communicate via the gut-brain axis (8). However, ongoing research is needed in this area, including larger and longer human studies. Similarly, more research is needed into gut-brain signalling after consuming dark chocolate.
The polyphenol level increases the darker the chocolate. Polyphenols are natural compounds found in plants that have a number of health-promoting benefits including acting as antioxidants. As polyphenols are known to be prebiotics (as they feed beneficial gut bacteria), it makes sense that 70% dark chocolate did not have the same positive impact as the 85% dark chocolate in this study.
Of course, there may also be other factors at play when it comes to the impact of chocolate on our mood. For example, the tastiness of chocolate and an emotional connection to this can be a significant factors. An interesting study from 2007 found that mood briefly improved after eating tasty chocolate, as compared with unsatisfying chocolate or nothing (9).
Summary:
This study found that consuming 85% dark chocolate led to improved diversity of the gut microbiome as well as improvements in mood.
These findings are in line with the evidence base in relation to the impact of dark chocolate on mood, how polyphenols promote gut diversity and how improved gut diversity is linked with improvements in mood.
It’s always important to highlight that although certain dietary factors are associated with improvements in mood, these shouldn’t be used in place of well-established mental health treatments. Always seek individual support if you are struggling with your mental health.
References:
Shin, J. H., Kim, C. S., Cha, L., Kim, S., Lee, S., Chae, S., … & Shin, D. M. (2022). Consumption of 85% cocoa dark chocolate improves mood in association with gut microbial changes in healthy adults: a randomized controlled trial. The Journal of Nutritional Biochemistry, 99, 108854. https://www.sciencedirect.com/science/article/pii/S0955286321002746
Shin, J. H., Kim, C. S., Cha, L., Kim, S., Lee, S., Chae, S., … & Shin, D. M. (2022). Consumption of 85% cocoa dark chocolate improves mood in association with gut microbial changes in healthy adults: a randomized controlled trial. The Journal of Nutritional Biochemistry, 99, 108854. https://www.sciencedirect.com/science/article/pii/S0955286321002746
CRIS – study registration “Effects of gut microbiome change on human’s mood by chocolate intake” https://cris.nih.go.kr/cris/search/detailSearch.do/17917
Jackson, S. E., Smith, L., Firth, J., Grabovac, I., Soysal, P., Koyanagi, A., … & Yang, L. (2019). Is there a relationship between chocolate consumption and symptoms of depression? A cross‐sectional survey of 13,626 US adults. Depression and anxiety, 36(10), 987-995. https://pubmed.ncbi.nlm.nih.gov/31356717/
Pase, M. P., Scholey, A. B., Pipingas, A., Kras, M., Nolidin, K., Gibbs, A., … & Stough, C. (2013). Cocoa polyphenols enhance positive mood states but not cognitive performance: a randomized, placebo-controlled trial. Journal of psychopharmacology, 27(5), 451-458. https://pubmed.ncbi.nlm.nih.gov/23364814/
Noonan, S., Zaveri, M., Macaninch, E., & Martyn, K. (2020). Food & mood: a review of supplementary prebiotic and probiotic interventions in the treatment of anxiety and depression in adults. BMJ Nutrition, Prevention & Health, 3(2), 351. https://nutrition.bmj.com/content/3/2/351
Clapp, M., Aurora, N., Herrera, L., Bhatia, M., Wilen, E., & Wakefield, S. (2017). Gut microbiota’s effect on mental health: The gut-brain axis. Clinics and practice, 7(4), 131-136. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641835/
Limbana, T., Khan, F., & Eskander, N. (2020). Gut microbiome and depression: How microbes affect the way we think. Cureus, 12(8). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7510518/
Macht, M., & Mueller, J. (2007). Immediate effects of chocolate on experimentally induced mood states. Appetite, 49(3), 667-674. https://www.sciencedirect.com/science/article/abs/pii/S019566630700298X
