I enjoy a good cup of coffee.
Not ten cups. Not something I need to carry around all day. Just a good cup in the morning.
I’ve experimented with giving it up, bringing it back, drinking water first, waiting a while before having it, and paying attention to how I feel.
These days, I generally enjoy a cup in the morning and get on with my life.
Apparently, coffee is another one of those things we’re supposed to worry about.
Too much caffeine. Bad for your heart. Makes you anxious. Interferes with sleep. Maybe you should switch to something else.
Depending on which decade you were paying attention, coffee has been treated as everything from a dangerous habit to a health food.
And now there’s another interesting piece of research.
Your gut has something to say about coffee
In April 2026, researchers published a study in Nature Communications examining how coffee affects the relationship between our gut microbiome and brain.
They weren’t simply asking whether people felt more awake after drinking coffee.
They wanted to understand what happened to gut bacteria, inflammation, stress, mood, and cognitive performance when people drank coffee, stopped drinking it, and then started again.
And they compared caffeinated coffee with decaffeinated coffee.
That last part is particularly interesting.
Because we’ve spent so much time talking about caffeine that it’s easy to forget coffee contains hundreds of other compounds.
Some of those compounds interact with the bacteria living in our digestive systems.
And those bacteria are involved in a great deal more than digestion.
Coffee isn’t just caffeine
The researchers found differences in gut bacteria between regular coffee drinkers and people who didn’t drink coffee.
They also found differences in several markers related to inflammation.
Regular coffee drinkers had lower levels of certain inflammatory markers, including C-reactive protein, and higher levels of an anti-inflammatory signaling molecule called IL-10.
When participants stopped drinking coffee, some of those measurements changed.
When coffee was reintroduced, the gut microbiome responded again.
That’s fascinating to me.
Something as ordinary as a cup of coffee can influence an entire community of microorganisms living inside us.
And those microorganisms are participating in conversations with the rest of the body that we’re only beginning to understand.
The study also found some improvements in reported stress, mood, and certain measures of attention when coffee was reintroduced.
But the results weren’t all in one direction. Coffee drinkers showed greater emotional reactivity in some comparisons, and people who didn’t drink coffee performed better on certain memory tests.
In other words, coffee is doing things we don’t completely understand yet.
Which is a considerably more interesting answer than simply declaring it good or bad.
We’ve been here before
I’ve watched nutritional advice change repeatedly over the years.
Eggs were dangerous. Then maybe they weren’t.
Fat was the enemy. Then certain fats became fashionable.
Coffee was something to limit. Then studies started finding associations with lower risks of several diseases.
Every few years, somebody seems ready to announce the final answer.
And every few years, another study reminds us that we haven’t figured everything out.
That’s one reason Peggy and I spend so much time experimenting with what works for us.
Not because research doesn’t matter. It does.
But because I don’t believe every human being responds identically to every food or drink.
I know people who can have coffee after dinner and sleep beautifully.
I’d rather not test that particular talent.
I also know people who get jittery after half a cup.
Why would I tell them to drink more because a study found something interesting about gut bacteria?
And why would I tell somebody who enjoys a morning cup, sleeps well, and feels good that they need to give it up?
There’s another study worth knowing about
In 2024, researchers published another large study in Nature Microbiology involving gut microbiome data from tens of thousands of people.
They found a particularly strong relationship between coffee consumption and a gut bacterium called Lawsonibacter asaccharolyticus.
Try saying that before your first cup.
The bacterium was substantially more abundant among coffee drinkers, and laboratory experiments showed that coffee could stimulate its growth.
Interestingly, decaffeinated coffee produced effects too.
That suggests some of coffee’s relationship with gut bacteria comes from compounds other than caffeine.
Researchers haven’t established exactly what all those changes mean for long-term health.
But we’re learning that coffee is much more biologically interesting than a simple caffeine delivery system.
So what am I doing with this information?
Having my morning coffee.
I enjoy it. I like the taste, the smell, and the little ritual of making it.
I generally drink it without sugar or flavored creamers. I don’t see much reason to turn a perfectly good cup of coffee into dessert.
And I pay attention to how I respond.
If coffee started interfering with my sleep or making me feel lousy, I’d change something.
I’ve done that before with plenty of other foods and habits.
But I’m not interested in giving up something I enjoy simply because somebody decided everybody should follow the same rule.
Especially when the research keeps revealing that the story is more complicated.
The funny thing is, coffee doesn’t need to be a miracle drink to deserve a place in somebody’s life.
It can just be coffee.
A good cup in the morning, enjoyed without guilt.
And perhaps doing a few interesting things inside us that we’re only beginning to discover.
That’s enough for me.
The research:
Boscaini S. and colleagues, “Habitual coffee intake shapes the gut microbiome and modifies host physiology and cognition,” Nature Communications, April 2026.
https://doi.org/10.1038/s41467-026-71264-8
Manghi P. and colleagues, “Coffee consumption is associated with intestinal Lawsonibacter asaccharolyticus abundance and prevalence across multiple cohorts,” Nature Microbiology, November 2024.