Habitual coffee intake shapes the microbiome, modifies physiology and cognition (opens in new tab)

After habitually consuming caffeine (not in coffee form) daily, usually multiple times a day, for more than a decade, a horrible mental health incident happened to me that forced me to stop it for a while. Afterwards I didn't resume the habit, and so I no longer have a tolerance.

This has let me evaluate what caffeine does with fresh eyes, so to say, because I can now consume it occasionally while having many non-caffeinated days to compare to. It's a profoundly psychoactive substance and does a lot of things to cognition. I guess I have decided I don't enjoy how it feels, having previously been dependent on it.

Funded by the Institute for Scientific Information on Coffee (ISIC) — an industry body — which is a notable conflict of interest the authors disclose but don't extensively discuss

I once quit caffeine cold for 6 months: 2 weeks of pure hell then it was like I never craved it until life got real and stressful and I fell off the wagon. Today, I drink my espresso with a dot of lowfat milk now and life is currently too real and stressful to consider trying to drop it again. I do suspect some of us likely have undiagnosed low-level mood disorders leaving us highly functional but discontent and caffeine is the spackling compound used to plug the hole in our souls.

thirty-one participants were moderate coffee-drinkers (CD, i.e., people that usually consume between 3 to 5 cups of coffee per day).

3-5 is moderate? To me, 3 is already high.

Also, sample size is pretty low and they're all Irish.

This paper is not saying coffee is bad.

If anything, it leans slightly toward beneficial or neutral effects.

What broader science says (not just this paper).

Across many large studies, Coffee is associated with:

* ↓ Lowerisk of Type 2 Diabetes

* ↓ risk of Parkinson’s Disease

* ↓ overall mortality (yes, really)

Downsides (for some people):

* Anxiety / jitters

* Poor sleep

* Increased heart rate

I drank a lot of coffee until I forgot to pack instant on a 3 day backpacking trip. Headache the whole time that I cured in 5 minutes by drinking a mt dew the minute we got back to civilization. Figured it wasn't worth it and weaned off.

Then it turned out my rate of getting migraines dropped off considerably. But I love coffee, so I tried decaf. Migraines returned to being more frequent. So that was that.

If I could get it without the side effects, I surely would. Right now I'm drinking a hot cup of delicious roasted barley tea. But it's not the same.

I’m super interested in this sort of study! However, it looks like n=62 here, which I think weakens the results —they’re probably just useful as suggestions of possible effects. Also, any food is expected to have similar effects on the microbiome. They didn’t test caffeine in isolation. In some ways that’s better (I don’t consume caffeine in isolation), but in some ways that’s less useful (it’s possible you get similar results from many random vegetables)

Caffeine is an extremely potent drug.

It’s actually kind of crazy to think that a large portion of a country’s population could be “high” on it basically all of the time. And there is a huge industry in place for delivering said drug to as many people as possible by having it available on almost every street corner.

And that most people take a fairly non-chalant attitude to giving this drug to kids through sweet drinks that are primarily marketed to them as well.

The scale of it is kinda mind boggling to me.

Mind the nonsensical rant, I haven’t had my coffee yet this morning…

I never used to drink any caffeine. In fact the few times I had tried it when I was a teen or my 20s it made my chest pound my heart raced so much. It was Lebanese strong cardamom coffee so maybe not the best example.

Then at age 34 I started a new job my first shift work job, late evenings, some overnight jobs. I started off with fancy coffee like french vanilla. A year or so later the first Starbucks opened. I was drinking venti quad shot lattes.

Then energy drinks were permitted for sale here (we had a can ban for years). I recall after drinking a Rockstar 750ml for breakfast and the following muscle spasms made me consider I should tone it down.

So I've settled a bit a small coffee in the evening. Sometimes I don't even finish it.

I switched from caffeine (coffee) to theacrine (pills) and I like it so much more. I feel alert and focused without added anxiety. It doesn’t seem to affect my sleep at all. I really didn’t like how hard it was to quit coffee.

I don’t like that it’s a pill. I tried making my own theacrine drinks, but theacrine is so bitter that I never found one that I liked. I am still haunted by the chicory + theacrine drink I made…

It's always amusing to read the self-narratives of a bunch of unacknowledged drug addicts when links like this get posted.

Habitual anything intake shapes the microbiome, modifies physiology and cognition

I stopped drinking coffee for four or five years. I drank a lot before. You do realise that it has a strong psychoactive effect, at least it did for me.

I still don't drink coffee, but I started experimenting with paraxanthine and I absolutely love it (paraxanthine is the primary metabolite of caffeine and is also a stimulant). I feel like it gives me most of the benefit of caffeine with very few downsides (no jitters, no crash, exits your system faster).

Here is a fun citation with a brief summary. They suggest regular caffine use lowers your baseline and it just returns you to where you'd be if you weren't dependent.

University of Bristol. "Coffee consumption unrelated to alertness: Stimulating effects may be illusion, study finds." ScienceDaily. ScienceDaily, 3 June 2010. <www.sciencedaily.com/releases/2010/06/100602211940.htm>.

What's cool is this effect exists even in decaf coffee, as someone who primarily drinks decaf black, for flavor and for a good night's rest as I'm sensitive to caffeine.

It would have been interesting to see if there was any difference relating to CYP1A2 (Cytochrome P450 1A2), the fast metabolizers and the slow metabolizers.

A very interesting article, I have personal experience with:

> Coffee also affects the gastrointestinal tract. It increases stomach acidity and stimulates the release of hormones that aid digestion. Both caffeinated and decaffeinated coffee promote the contractility of ileal and colonic smooth muscle, helping prevent constipation

As the two times in my adult life I've tried to make an intended break from coffee, it has ended up with almost unbearable stomach pain caused by constipation.

It's good to know that this is not linked to caffeine as I thought, so I will try un-caffinated coffee instead now because I tend to think that my general "tiredness" comes from actual caffeine.

Coffee modifies physiology and cognition? You're telling me this for the first time.

At least subjectively, coffee seems to help my memory. But maybe that's why I started drinking coffee?

I would probably drop coffee it was proven to have negative effects on memory.

I am not a coffee drinker, but I met with a friend at a cafe who said he was going to get a cup of insect poison, referring to coffee :)

What surprises me is how many people drink coffee first thing in the morning. The organism is literally in wake-up mode, with cortisol spiking ~30min after wake up. So you get a caffeine AND a spike in cortisol at the same time.

Better to wait at least couple of hours after waking up.

We know, that’s why we do it.

Was this thread invaded by AI? Casually reading the first comments, 3 different users mentioned they had a recent "mental health incident" related to caffeine??

Search this page for "mental health incident"

I have not much followed the science of gut microbiome and psychology. Is this really going where this article is pointing? That we can tease out causation in foods and habits via gut microbiome towards behavior and psychology? Pretty rad.

I must be weird, but coffee (or caffeine) doesn’t really “wake me up” in the mornings and I could drink it in the night and still sleep well. Because of that I don’t drink coffee; I prefer tea

Would be real interesting to see a similar study on tea.

Every study like this should clearly state who paid for it.

Institute for Scientific Information on Coffee

I used to drink a small amount of blisteringly strong coffee in the morning and after lunch, but nowadays I drink a massive amount of relatively weak coffee throughout the entire day. Weaker than you'd ever get from a shop or in an office.

That's been a big win for me: I feel like I get to enjoy the coffee more, and it eliminated the negative effects for me.

I no longer feel like I suffer when I don't have it. I miss it, the way I miss the sunlight in my office on a cloudy morning, but it's strictly a positive for me when it's around. I only get headaches if I go from 100 to 0, even one day of reduced intake is enough to avoid it for me.

When I'm exhausted and going to bed, I'll go fill the coffee machine, and catch myself thinking "oh boy, it's going to feel so great to wake up at 6am and drink this". Then I shake my head at myself and laugh and how absurd that sounds :D

Coffee is above running hot water in my hierarchy of needs. Seriously. If I were forced to choose between coffee and alcohol for the rest of my life, I'd choose coffee in a heartbeat.

> The coffee provided was consumed with a quantity of hot water, milk, sugar chosen by the participant.

Could it be the sugar?

This discussion has been particularly insightful. I'm 47 and have been drinking 2 to 3 Mtn Dew Kickstarts a day for probably 10 years. I don't feel high, or jittery, or like I'm bouncing off walls. I have no trouble falling asleep, even drinking caffeine right up until bed time. But, I also have trouble focusing, am working with a psychologist on a possible ADHD (primarily inattentive) diagnosis, never dream, and am very forgetful.

Based on everything I'm reading below, and a "discussion" with Gemini, it's highly probable all of this is related. I know AI isn't a doctor, and confirmation bias and all of that, but even if it's all nonsense - backing off on caffeine or quitting entirely can only help.

So I'm going to star to day, by trying to not have any after 2pm. My regular bedtime is around midnight, so that's 10 hours. We'll see how it goes.

Thanks HN!

If coffee was a god, I would pray to it.

I am reading the comments and wonde about the spread of individual sensitivity.

I drink 3 to 6 Nespresso coffees daily, at various times, including shortly before going to bed. Sometimes I don't drink at all for a few days.

I don't feel any effects related to the number, or whether I drink it or not. Sure, this is subjective but when I compare myself to the stories of the commenters I start to wonder if there is any caffeine at all in what I drink.

Yes, well, nevertheless. Sip

> ... reintroduction triggered acute microbiome changes independent of caffeine.

This sounds interesting. I've never really considered the constituents of coffee other than caffeine and what unique effects they may bring.

I wonder if I would experience behavioral effects if I replaced my coffee intake with caffeinated non-coffee drinks or pills?

The only good thing that keeps me from collapsing into a state of limbo is coffee and now, even that's bad (seems more like a mixed bag, but still)? Sigh.

I only use caffeine or caffeinated beverages such as coffee at the most three times a week. And that's a heavy week for me.

good thing I have claude to summarize this and quickly realized that sample size was small and nothing much new unless you are a microbiome researcher

Congrats to this team, providing exceptional research on how coffee affects us physically and mentally. I think moderation is key.

"These findings reveal previously unrecognised effects of coffee on the microbiota–gut–brain axis, suggesting that microbiome profiles could potentially predict coffee consumption patterns", or, perhaps, just ask the patient?