March 24, 2026, 8:22 pm | Read time: 4 minutes
It’s the classic among morning rituals—especially as a pick-me-up. A large long-term study suggests that coffee might also play a role in mental health. The study looked closely at depression and stress-related disorders. Important: the right number of cups per day.
Different Coffee Types in Focus
Chinese scientists from Fudan University examined whether daily coffee consumption is linked to the later risk of mental disorders. Is coffee beneficial, detrimental, or without a clear connection to mental health? They were also interested in whether there are differences between genders and if the genetically influenced ability to metabolize caffeine plays a role.1
They looked not only at coffee overall but also at different subtypes:
- Instant coffee
- Ground coffee
- Decaffeinated coffee
The Disorders Explained Briefly
The focus of the study was on mood and stress disorders (also: affective disorders and stress disorders). Mood disorders include conditions that significantly affect emotional state, such as depression. Stress disorders involve psychological issues in response to traumatic events (e.g., violence) or prolonged, extreme stress. Major forms include post-traumatic stress disorder, or PTSD.
Data from Over 400,000 People
The study was based on data from the UK Biobank, a large prospective population study. A total of 461,586 participants were initially recorded and then observed over the years to see who later developed mental disorders. Forty-six point four percent of the participants were men, and the average age was 57 years.
At the start, participants provided information about their coffee consumption, including the type of coffee, such as instant, ground, or decaffeinated coffee. Over time, the authors recorded mood disorders and stress-related disorders using ICD-10 codes from inpatient hospital data.
For statistical analysis, they used specific regression models that help calculate disease risks over time and reveal nonlinear patterns. Additionally, the researchers examined whether gender or genetic differences in caffeine metabolism influenced the connection.
2 to 3 Cups of Coffee Linked to Lower Risk
During a median follow-up period of 13.4 years, 18,220 people developed mood disorders and 18,547 developed stress disorders. “Median” means that half of the participants were observed for a shorter time, and the other half for a longer time.
The central observation was a J-shaped relationship between coffee consumption and mental disorders. This means the risk wasn’t simply lower with each additional cup but reached its most favorable range with moderate consumption. Those who drank two to three cups of coffee a day had the lowest risk of developing mental health issues compared to those who drank none or more than three cups. Five or more cups were even associated with an increased risk of mood disorders, showing that “more” doesn’t automatically mean “better.”
Caffeine, Genes, and Gender
The J-pattern persisted across different coffee types, suggesting that the connection can’t be explained solely by caffeine. Additionally, the link was more pronounced for mood disorders in men than in women. However, the researchers found no evidence that genetic variants of caffeine metabolism significantly altered the observed connections.
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Significance of the Results
The background of the work is relevant to health policy: Mental disorders have been among the major burdens on public health for years. In 2024, mental illnesses ranked third among disease groups causing the most work absences. According to the 2025 DAK Psych Report, depression caused the most of these in 2024: about 183 days of absence per 100 insured individuals.2 In general, mood disorders, with 9.8 percent affected, are among the most common mental illnesses in Germany (including depression: 8.2 percent).3
There is considerable interest in easily implementable prevention approaches. The results are intriguing as they point to a connection relevant to everyday life. Coffee is one of the most frequently consumed beverages worldwide. If moderate consumption is linked to a lower risk of certain mental disorders, it would be practically relevant for many people.
Study Assessment and Conclusion
It’s important to understand that the study shows a statistical connection, not a cause-and-effect relationship. Nevertheless, it’s noteworthy that in this long-term study with over 400,000 participants, moderate coffee consumption is associated with the lowest risk for mood and stress-related disorders. The encouraging point: Even everyday habits like drinking coffee could be more significant for mental health than previously thought.