The coffee gut microbiome connection is one of the clearest links between a single food and specific gut bacteria that scientists have found. A 2024 study in Nature Microbiology, with 22,867 participants in its main analysis and data from 54,198 people across 211 cohorts, found that people who drink a lot of coffee carry roughly 4.5 to 8 times more of a bacterium called Lawsonibacter asaccharolyticus than people who drink none. Decaf drinkers showed the same pattern.
That is a striking result, but it is also a starting point rather than a health promise. This article explains what the research actually shows about coffee and gut bacteria, which coffee compounds reach the colon, what coffee does along the digestive tract, what is still unknown, and who should be careful.
Last updated: 06 October 2026. This article is general information from a coffee supplier, not medical advice. If you have a digestive condition, talk to your doctor about coffee.
What Is the Gut Microbiome, and Where Does Coffee Fit?
The gut microbiome is the community of bacteria, fungi and other microbes living in your digestive tract, most of them in the colon. The often-quoted figure of 100 trillion microbes is out of date. A 2016 analysis in PLoS Biology by Sender, Fuchs and Milo estimated about 38 trillion bacteria in a 70 kg adult, roughly the same number as human cells, weighing about 0.2 kg in total.
These bacteria ferment food we cannot digest ourselves, such as fibre and many plant compounds, and produce substances that influence digestion, immunity and metabolism. What you eat and drink every day is one of the strongest influences on which bacteria thrive, which is why a daily habit like coffee shows up so clearly in coffee gut microbiome research.
The 2024 Coffee Gut Microbiome Discovery: Lawsonibacter
The 2024 Nature Microbiology study compared coffee intake with gut bacteria across large international cohorts.
| Finding | Detail |
|---|---|
| Scale | 22,867 participants in the main analysis; 54,198 people across 211 cohorts including public data |
| Main result | Lawsonibacter asaccharolyticus was 4.5 to 8 times more abundant in high coffee drinkers than in non-drinkers |
| Decaf | The association held for decaffeinated coffee, so caffeine is not the main driver |
| Lab test | Coffee stimulated the growth of the bacterium in vitro |
| Metabolites | Coffee drinkers carrying the bacterium had more quinic acid and trigonelline, compounds found in coffee |
What the study did not show is whether having more Lawsonibacter is good for health. The bacterium was only described in 2018, as a butyrate-producing species isolated from human faeces, and its role in the body is still being studied. The honest summary of this coffee gut microbiome research: coffee clearly changes the gut microbiome; whether that particular change is beneficial is not yet known.
How Coffee Compounds Reach Your Gut Microbiome
Most of what drives the coffee gut microbiome link is not caffeine, which is absorbed early in the digestive tract. It is the plant compounds that pass through to the colon largely intact.
| Compound | Where it comes from | What happens in the gut | Effect of roasting |
|---|---|---|---|
| Chlorogenic acids (polyphenols) | Present in the green bean | A large share is not absorbed in the small intestine and is broken down by colon bacteria into smaller metabolites | Decrease as roasts get darker |
| Quinic acid | Released from chlorogenic acids, increases with roasting | Linked to Lawsonibacter in the 2024 study | Increases with roasting |
| Trigonelline | Present in the green bean | Linked to Lawsonibacter in the 2024 study | Partly broken down by roasting |
| Melanoidins | Brown compounds formed during roasting | Not digested; can be fermented by colon bacteria | Increase as roasts get darker |
| Soluble fibre | Small amounts in brewed coffee | Fermented by colon bacteria | Varies |
For a fuller list of what is in the cup, see our guide to bioactive compounds in coffee.
What Coffee Does Along the Digestive Tract
A 2022 review in Nutrients by Astrid Nehlig pulled together the research on coffee and the gastrointestinal tract. It separates effects that are fairly clear from those that remain controversial.
| Effect | What the evidence shows | Strength of evidence |
|---|---|---|
| Stomach acid | Coffee stimulates gastric acid secretion; caffeinated coffee raises gastrin, the hormone behind it, more than decaf | Fairly clear |
| Bile and pancreas | Coffee stimulates biliary and pancreatic secretion | Fairly clear |
| Gallstones | Coffee intake was associated with a 17% lower risk of gallstones in prospective studies | Fairly clear |
| Colon movement | Regular coffee stimulates the colon about as much as a cereal meal, 23% more than decaf and 60% more than water; about 29% of people feel an urge to go | Fairly clear |
| Gut bacteria | Coffee changes microbiota composition; in one study, 3 cups a day for 3 weeks increased the metabolic activity of Bifidobacterium | Fairly clear that it changes; health meaning still unclear |
| Reflux, ulcers, inflammatory bowel disease | Results are inconsistent | Controversial |
Bifidobacterium is one of the bacterial groups most often associated with a healthy gut, which is why the volunteer study attracts attention. It was small and short, though, so it supports the direction of the effect rather than proving a health benefit. That is the pattern across coffee gut microbiome studies so far: clear changes, unproven health effects.
Coffee, the Gut Microbiome and the Brain: Promising but Early
The gut and the brain communicate constantly through nerves, hormones and immune signals, and gut bacteria take part in that conversation; a review in Annals of Gastroenterology describes the system. It is tempting to connect this to the coffee gut microbiome story and claim that coffee improves mood through the gut. There is not yet good evidence for that specific chain of effects in people. Caffeine’s direct effects on alertness are well established; mood benefits running through gut bacteria are a hypothesis, not a finding.
Does Decaf, Roast or Brewing Method Matter?
Decaf. In the 2024 study, decaf drinkers showed the same Lawsonibacter pattern, and decaf keeps most of the polyphenols. If caffeine disturbs your sleep or stomach, decaf is a sound choice for gut-related reasons. Our guide to caffeine in decaf explains how much remains.
Roast level. Lighter roasts keep more chlorogenic acids; darker roasts contain more melanoidins. There is no evidence that one roast is better for the microbiome than the other, so choose the coffee you enjoy.
Fermented coffee is not probiotic. Coffee processing often involves fermentation at the farm, but roasting heats the beans to around 200°C, which kills the microbes involved. No live bacteria reach your cup. See our article on fermented coffee beans for what fermentation does change.
What you add. Sugar and sweetened creamers are a separate issue from coffee itself. In diabetes research, added sugar weakened coffee’s benefits; see our guide to coffee and blood sugar.
Who Should Be Careful With Coffee
- Reflux or heartburn. Coffee stimulates stomach acid. Research on reflux is inconsistent, but if coffee triggers your symptoms, that matters more than population averages; our article on coffee and GERD covers practical adjustments.
- Irritable bowel syndrome. Coffee’s effect on colon movement can worsen urgency for some people with IBS. Our coffee and low FODMAP guide explains where coffee fits in an IBS diet.
- Pregnancy. Caffeine intake is usually limited to about 200 mg a day; ask your doctor.
- Everyone else. Health authorities consider up to 400 mg of caffeine a day, roughly four cups of brewed coffee, safe for most healthy adults.
How to Drink Coffee for a Healthy Gut Microbiome
These habits fit what coffee gut microbiome research currently supports:
- Drink it black or with a little milk. Keep sugar and sweetened creamers to a minimum.
- Stay moderate. Up to about three or four cups a day for most healthy adults; less if you are sensitive.
- Remember decaf counts. The gut bacteria associations in the 2024 study held for decaf.
- Pair it with fibre. Coffee is not a substitute for vegetables, fruit, legumes and whole grains, which feed far more gut bacteria than coffee does.
- Notice your own response. Reflux, urgency or stomach pain are signals to adjust timing, amount or roast.
- Store beans well. Fresh, airtight-stored coffee tastes better black, which makes the sugar-free habit easier. A good coffee canister helps.
Frequently Asked Questions
Is coffee good for your gut microbiome?
Coffee gut microbiome research shows coffee clearly changes the gut microbiome. A 2024 study of more than 22,000 people found coffee drinkers carry 4.5 to 8 times more of the bacterium Lawsonibacter asaccharolyticus, and earlier research linked coffee to more active Bifidobacterium. Whether these changes improve health is not yet proven, so treat coffee as part of a fibre-rich diet.
What is Lawsonibacter asaccharolyticus?
Lawsonibacter asaccharolyticus is a gut bacterium first described in 2018. A 2024 Nature Microbiology study found it is strongly linked to coffee drinking, at 4.5 to 8 times higher abundance in heavy coffee drinkers, and that coffee helps it grow in the lab. Its effects on human health are still being studied.
Does decaf coffee affect the gut microbiome?
Yes. In the 2024 Nature Microbiology study, the link between coffee and Lawsonibacter asaccharolyticus also held for decaffeinated coffee, which suggests compounds other than caffeine, such as quinic acid and trigonelline, drive the effect. Decaf also keeps most of coffee’s polyphenols, so it remains relevant to gut bacteria.
Why does coffee make you poop?
Coffee stimulates the colon. A 2022 review reports that regular coffee stimulates colonic movement about as much as a meal, 60 percent more than water and 23 percent more than decaf, and that about 29 percent of people feel an urge to go after drinking it. Caffeine contributes, but decaf has an effect too.
Is coffee a prebiotic?
Not officially, but it behaves partly like one. Coffee polyphenols, melanoidins and small amounts of soluble fibre reach the colon, where bacteria ferment them, and studies link coffee to changes in Bifidobacterium and other bacteria. Coffee is far less important than fibre-rich foods such as vegetables, legumes and whole grains.
Can coffee upset your stomach or gut?
It can for some people. Coffee stimulates stomach acid and colon movement, which may trigger heartburn or urgency, particularly in people with reflux or irritable bowel syndrome. Research on reflux is inconsistent, so personal response matters most. Try smaller amounts, decaf, or drinking coffee with food.
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