Dark chocolate, mood and gut bacteria in healthy adults
What it found
Healthy adults who ate 30 g a day of 85% cocoa dark chocolate for 3 weeks had lower negative affect scores than those who ate no chocolate.
The 70% cocoa chocolate did not have this effect.
What they found
Studies in people
Mood change
Daily eating of 85% cocoa dark chocolate significantly reduced negative affect. The 70% cocoa chocolate did not reduce negative affect.
Gut bacteria diversity
Gut microbial diversity was significantly higher in the 85% cocoa group than in the control group.
Specific gut bacteria
Blautia obeum levels were significantly elevated and Faecalibacterium prausnitzii levels were reduced in the 85% cocoa group compared to the control group.
Mood and bacteria link
Changes in negative affect scores were negatively correlated with diversity and relative abundance of Blautia obeum.
What the authors conclude
“These findings indicate that dark chocolate exerts prebiotic effects, as evidenced by its ability to restructure the diversity and abundance of intestinal bacteria; thus, it may improve negative emotional states via the gut-brain axis.”
Also in their conclusions
- They say these findings indicate that dark chocolate exerts prebiotic effects, as evidenced by its ability to restructure the diversity and abundance of intestinal bacteria.
- They conclude that dark chocolate may improve negative emotional states via the gut-brain axis.
How it was done
Dark chocolate has long been recognized for its mood-altering properties, but the evidence on the emotional effects of daily dark chocolate intake is limited. The authors wanted to look at mood in everyday life, with a focus on the gut-brain axis.
In a randomized controlled trial, healthy adults aged 20 to 30 ate either 30 g a day of 85% cocoa chocolate, 30 g a day of 70% cocoa chocolate, or no chocolate, for 3 weeks. There were 18 people in the 85% group, 16 in the 70% group and 14 in the control group. Mood was measured with the Positive and Negative Affect Schedule, and gut bacteria were analysed from stool samples in the 85% and control groups.
What it can’t tell you
- We summarised it from the abstract only.
- The trial was small, with 18 people in the 85% cocoa group, 16 in the 70% group and 14 in the control group.
- It lasted only 3 weeks, so it cannot show what happens over longer periods.
- It cannot show whether the mood changes were caused by the gut bacteria changes or by something else in the chocolate.
Who paid
- Authors work at
- Seoul National University, Republic of Korea; Korea Food Research Institute, Republic of Korea; Chungnam National University, Republic of Korea
The paper
- Title
- Consumption of 85% cocoa dark chocolate improves mood in association with gut microbial changes in healthy adults: a randomized controlled trial
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Shin JH, Kim CS, Cha J, et al (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. doi:10.1016/j.jnutbio.2021.108854PubMed 34530112DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error