Caffeinated coffee consumption or abstinence to reduce atrial fibrillation
15 comments
·November 15, 2025hereme888
carbocation
To add more information, the intervention was guidance about caffeine intake. From the Methods:
> If allocated to caffeinated coffee consumption, patients were encouraged to drink at least 1 cup of caffeinated coffee (or at least 1 espresso shot) and other caffeine-containing products every day as per their usual lifestyle. It was recommended that patients in the coffee consumption group not intentionally increase or decrease consumption of coffee or other caffeine-containing products.
> If allocated to the abstinence group, patients were encouraged to completely abstain from coffee, including decaffeinated coffee, and other caffeine containing products.
827a
The people who were selected into the study were not necessarily "habitual coffee drinkers". The only requirement was "was a habitual coffee drinker sometime in the past five years". The difference between the two is subtle, but its possible there were people in the study who had already abstained for some amount of time.
embedding-shape
> If allocated to caffeinated coffee consumption, patients were encouraged to drink at least 1 cup of caffeinated coffee (or at least 1 espresso shot) and other caffeine-containing products every day as per their usual lifestyle
I tried to skim to figure out how much caffeine/ml was actually in the drinks, but seems the researchers don't know themselves either? Wouldn't there be a huge difference depending on the beans, how it's made and so on? 1 espresso can be made very strong with packed coffee, or it can be made very weak, "1 cup of caffeinated coffee" basically says nothing at all, unless I'm missing the true definition elsewhere in the paper.
dehrmann
I researched this a bit and found there really is no standardized "cup of coffee" for research purposes. Even for volume, I've seen it range from 6 to 12 fl oz. The main mechanisms of action are caffeine and flavonoids, and there's so much variation across beans and brewing methods that you'd think researchers would try to include that in their data to normalize it.
wcunning
James Hoffman did some interesting videos on that -- espresso is a more efficient extraction method than Aeropress, but less complete than a very high water to coffee ratio pour over for the same weight of ground coffee. Extraction of caffeine is very directly tied to contact time and temperature, so two double shots of espresso (40g coffee) can actually be less caffeine extracted than a single large pour over (25g coffee) when the pour over is upwards of 22% extraction (typical of 20:1 water to coffee ratios and modern zero-bypass brewers). Similarly, there are large differences in beans, so 22% extraction on weak caffeine beans might be way less than 18% extraction on much higher caffeine beans. This is most obvious in the fact that Robusta has much higher caffeine on average than Arabica. Also, 22% extraction has a lot more unpleasant bitter compounds, not just more caffeine, so it's not my preference for taste in general.
sroussey
Coffee makes me jittery but espresso (or lattes) do not. Is this why?
nosianu
Maybe?
As an espresso drinker with a good machine and grinder, and lots of variety with mostly Italian beans, it depends, as the OP already indicated. I only buy low or at most middle caffein content beans to begin with, but you can get high caffeine beans for espresso easily. Easiest method: Increase the amount of Robusta.
Good vendors should have things like caffein content in their product description. I mostly buy from an online vendor that lists the exact roast date and also shows caffein content for each product (https://www.espresso-international.com/ - their only disadvantage is the use of some pretty light GRAY for most text, another topic, too many websites do this for reasons I cannot understand).
Many years ago, when I still lived in the Bay Area, the Cappuccino I got at a certain Berkeley coffee shop always made my heart go BOOM BOOM BOOM. Whatever concoction they brewed certainly had very high caffein (and I hated it, but the place was great). The ones I make myself now I can drink at 10 pm and be completely fine (I only drink 2-4 max espresso per day, and can easily drink zero if I'm away and have no access to good espresso, so I'm not addicted and just "used to it").
Sometimes I compromise and buy medium caffein beans when it's something good, but those I can feel just a little.
All of that just means you have to exert some control over which beans you consume, if you want to keep caffein low. On the plus side, if you stick to 80%-100% Arabica (the rest Robusta) it's not hard at all. If you like mixes with high Robusta ratio it gets much harder. Caffein free roasts exist though (examples: https://www.espresso-international.com/decaffeinated-coffee), but that choice severely limits your options.
andrewmcwatters
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AJMaxwell
It's probably whatever "1 cup" means to the patient. The researchers would want them to stick to their status quo for the best results.
For example, 1 cup of coffee for my wife involves a blend of coffee and espresso beans with no adders, but 1 cup to her dad means lighter roast bean with milk. Both options have different caffeine contents and nutritional values.
brnt
A weak espresso sounds like you're just making a small amount of American/German coffee. How could that be passed of as an espresso? It's not just a measure of volume.
jerlam
> The DECAF Randomized Clinical Trial
> The DECAF (Does Eliminating Coffee Avoid Fibrillation?) trial...
Fantastic naming.
FrankWilhoit
I, too, have found that in the presence of a-fib, the optimal amount of caffeine is not zero; but I must think that every patient is different. Most people with diagnosed a-fib also take a beta blocker, and I (just only me) found that an excess of the beta blocker had paradoxical effects. So there is another potential interaction. Then, I also voted myself a small dose of OTC lithium, and subjectively derived obvious and substantial benefit from it, but there is (as yet) no science behind that, so I will not assert causation.
zengid
love to hear good news even if it's a relatively small sample size. anecdotal, but i've heard that the antioxidants in fresh ground coffee is also very good!
bell-cot
In the context of HN, the title is fairly misleading.
Suggestion: Got to the article, hit PgDn a few times, and look at the "Visual Abstract" graphic - which is both very short, and packed with important details.
Poor title. This is specific to patients who already underwent cardioversion (shocking the heart back into normal rhythm) AND were habitual coffee drinkers, who now have reduced coffee to 1 cup/day rather than sudden complete abstinence. Recurrence at 6 months was 47% instead of 64%. And this only applies to those who don't have clear caffeine-associated episodes.