Dark chocolate, mood and gut bacteria in healthy young adults
What it found
Eating 30 g of 85% cocoa dark chocolate daily for three weeks lowered negative feelings in healthy young adults.
This change was linked to shifts in their gut bacteria.
What they found
Studies in people
Mood and cocoa content
People eating 85% cocoa chocolate reported fewer negative feelings after three weeks. Those eating 70% cocoa chocolate showed no clear difference compared to the group eating no chocolate. Neither type changed positive feelings.
Gut bacteria variety
The 85% cocoa group had more types of gut bacteria after three weeks than the group eating no chocolate. Two specific bacterial species also shifted in amount.
Bacteria and mood link
The drop in negative feelings matched the rise in overall gut bacteria variety. It also matched higher levels of one specific bacterium called Blautia obeum.
Other findings
Polyphenol dose differences
The 85% cocoa group took in about 400 mg of polyphenols each day, while the 70% group took in about 250 mg. The authors suggest this higher dose may explain why only the 85% chocolate changed mood.
What the authors conclude
- They suggest that 85% cocoa dark chocolate acts as food for gut bacteria, changing the mix of microbes in the intestine.
- They propose that these microbial shifts may improve negative moods through the connection between the gut and the brain.
- They call for future research with placebo controls to confirm how gut bacteria influence mood after eating dark chocolate.
How it was done
Mood problems are common worldwide, and current drugs often work slowly or not well for many people. Scientists wanted to know if everyday dark chocolate could improve mood through changes in gut bacteria.
They randomly assigned 48 healthy adults aged 20 to 30 to eat 30 g a day of 85% cocoa chocolate, 30 g of 70% cocoa chocolate, or no chocolate. Everyone followed this routine for three weeks while researchers tracked their moods and gut bacteria.
What it can’t tell you
- Participants knew whether they were in the chocolate groups or the no-chocolate group, which might have influenced how they reported their moods.
- The study lasted only three weeks, so it cannot show what happens when people eat dark chocolate over months or years.
- It tested healthy young adults, so the results might not apply to older people or those with diagnosed mood disorders.
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
- Full text
- 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.2021.108854Free full textPubMed 34530112DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error