Drinking coffee alters your microbiome, mood, and memory

From your gut microbes to your mood and memory, new research reveals how daily coffee habits may shape brain function in ways that go far beyond caffeine.

Study: Habitual coffee intake shapes the gut microbiome and modifies host physiology and cognition. Image credit: franz12/Shutterstock.com

A recent Nature Communications study investigated whether habitual coffee consumption affects the microbiota–gut–brain axis and explored if these effects are independent of caffeine in healthy adults.

Bioactive coffee components influence gut and neurological pathways

Coffee is one of the most widely consumed beverages worldwide, enjoyed for its distinctive flavor and stimulating properties. Roasted coffee contains bioactive compounds, including caffeine, phenolic acids, diterpenes, and melanoidins, with health-promoting properties. These compounds are associated with reduced risks of chronic diseases such as type 2 diabetes, liver and cardiovascular disease, certain cancers, and neurological conditions. Moderate coffee consumption also correlates with lower mortality and stroke risk.

Coffee directly affects the brain by altering neural activity and cognitive performance. Regular consumption changes connectivity in sensory, motor, and emotional regions, potentially influencing brain function and emotional regulation. Studies have linked coffee consumption to improved memory and processing speed, particularly in older adults. However, the impact of coffee on stress remains uncertain due to inconsistent findings.

Bioactive components of coffee, such as chlorogenic acids and melanoidins, are associated with changes in gut microbial populations and increase short-chain fatty acid (SCFA) levels. Differences in individual microbiomes shape the metabolism of these compounds. Coffee phenolics may also help reduce neuroinflammation by activating antioxidant pathways in the brain.

Large-scale metagenomics studies indicate that coffee is a major dietary factor shaping gut microbiome composition in a dose-dependent manner, particularly by increasing certain microbial species, including taxa identified in prior studies as butyrate producers. While these results highlight the potential for coffee to impact cognition via the microbiota–gut–brain axis, significant research gaps persist.

The timing and duration of coffee’s effects and withdrawal remain poorly defined. In addition, the microbiome’s precise mediating role in the relationship between coffee intake and brain function remains unclear.

Isolating caffeine versus non-caffeine effects 

This study explores how coffee consumption, withdrawal, and reintroduction affect cognition, mood, and behavior through the microbiota-gut-brain axis. A total of 62 healthy adults aged 30-50 from Ireland participated. Of which 31 were non-coffee drinkers (NCD), and 31 were moderate coffee drinkers (CD) who drank 3–5 cups a day. Any participants with a history of acute or chronic coexisting illness, under any medication, habitual consumer of high quantities of fermented foods, pregnant, or lactating were excluded.

At baseline, selected participants underwent a physical exam, provided blood and fecal samples, completed questionnaires, and cognitive tasks. After baseline, NCDs did not continue in the subsequent study phases.

Before the intervention, CDs abstained from coffee, other caffeinated beverages, and dark chocolate for 2 weeks and were randomly assigned to either a caffeinated (n=16) or a decaffeinated (n=15) coffee group in a double-blind, parallel design. Subsequently, the effect of a 3-week intervention of four sachets per day of assigned coffee (caffeinated or decaf) was assessed.

Coffee alters behavior, metabolites, and microbial composition patterns

The majority of participants were female. CDs consumed more caffeine than NCDs, but other lifestyle factors and genetic profiles were similar between the groups. No significant dietary differences were observed, and dietary intake remained largely stable throughout the study.

General well-being assessments showed no differences between groups. During the intervention, coffee abstinence led to lower blood pressure in CDs, while caffeinated coffee reduced systolic blood pressure compared to decaffeinated coffee.

CDs exhibited higher impulsivity and emotional reactivity scores than NCDs. Coffee abstinence reduced impulsivity and emotional reactivity in CDs and improved cognitive performance, potentially due to practice effects from repeated testing.

Caffeinated coffee reduced anxiety and enhanced cognitive performance, while decaffeinated coffee improved memory, sleep quality, and physical activity. Only caffeinated coffee resulted in lower salivary cortisol after the intervention. Both coffee types reduced perceived stress, depression, and impulsivity, but neither significantly affected stress resilience. Caffeinated coffee improved self-concept and coping abilities, whereas decaffeinated coffee increased positive affect.

Memory performance was comparable between groups at baseline. Only decaffeinated coffee led to significant improvements in episodic memory, potentially due to improved sleep and increased physical activity. During coffee withdrawal, cravings remained stable, while withdrawal symptoms decreased rapidly. These included reductions in drowsiness, headaches, and fatigue, whilst energy levels increased. Decaffeinated coffee led to greater drowsiness and fatigue, whereas caffeinated coffee improved mood and mitigated withdrawal symptoms.

Caffeinated coffee reduced IL-10 and IL-6, while decaffeinated coffee raised C-reactive protein (CRP) and tumor necrosis factor alpha (TNFα). These findings suggest coffee and caffeine modulate immune responses, with context-dependent and sometimes contrasting effects on inflammatory markers. NCDs exhibited a greater IL-6 response at baseline. Both coffee types lowered IL-6 following the intervention, and decaffeinated coffee also reduced TNFα secretion. These results indicate coffee components may influence immune responsiveness.

CDs exhibited higher fecal concentrations of caffeine, theophylline, 1,7-dimethylxanthine, and hippuric acid, and lower levels of indoles and gamma-aminobutyric acid (GABA), an important inhibitory neurotransmitter in the central nervous system that plays a key role in regulating mood, anxiety, and cognitive function, compared to NCDs.

Coffee abstinence reduced these metabolites, while reintroduction produced shifts depending on the type of coffee consumed. These results suggest that coffee consumption is associated with changes in gut metabolite profiles, with distinct effects based on caffeine content.

CDs excreted higher levels of caffeine metabolites and phenolic compounds in urine compared to NCDs, reflecting differences in coffee and polyphenol metabolism. After coffee abstinence, the urinary metabolite profiles of CDs resembled those of NCDs, except for a few unchanged metabolites.

CDs also had higher fecal concentrations of certain benzoic and cinnamic acid derivatives, which decreased during abstinence and rose again after reintroduction, independent of caffeine content. Urinary polyphenol metabolites correlated with specific microbial species and other metabolites, which were strongly associated with cognitive outcomes.

Coffee abstinence and reintroduction resulted in dynamic shifts in microbial populations, regardless of caffeine content. While microbiota diversity differed between NCDs and CDs, it remained stable within the CD group after the intervention, indicating that coffee influences specific microbial strains rather than overall diversity.

Coffee influences gut-brain axis through complex biological pathways

The current study reveals how coffee consumption shapes emotional, immune, and microbial responses, underscoring its role in influencing the microbiota-gut-brain axis. Sustained impacts following periods of abstinence and nuanced effects from reintroduction highlight both caffeine-specific and broader coffee influences. 

Notably, NCDs exhibited lower impulsivity and emotional reactivity at baseline, suggesting more stable behavioral and physiological profiles in the absence of habitual coffee intake.

Detailed metabolic profiling and multi-omics integration provide new insights into interconnected relationships between coffee intake and the microbiome. The findings demonstrate immediate and lasting changes in microbial activity and altered levels of neuroactive metabolites, opening avenues for future research and potential health applications.

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