r/science • u/mvea Professor | Medicine • 17d ago

Health Boiled coffee in a pot contains high levels of the worst of cholesterol-elevating substances. Coffee from most coffee machines in workplaces also contains high levels of cholesterol-elevating substances. However, regular paper filter coffee makers filter out most of these substances, finds study.

https://www.uu.se/en/press/press-releases/2025/2025-03-21-cholesterol-elevating-substances-in-coffee-from-machines-at-work
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u/SeyiDALegend 17d ago

I wonder how French press coffee factors into this

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u/heteromer 17d ago

The French press and percolators had around 3 times the amount of diterpenes than filtered coffee, although it was still much lower than unfiltered coffee.

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u/itwentok 17d ago

Yep, here's the relevant table from the research paper: Table 1 Concentrations of diterpenes cafestol and kahweol in different coffee brews (mg/L).

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u/Dhun101 17d ago

Oh no. Is espresso the worst?

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u/thegooddoktorjones 17d ago

Does cold brew press have the same levels?

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u/DessertTwink 17d ago

I've only made cold brew in a commercial setting for coffee shops, but those coffee grounds are contained within a sealed paper bag or a cheese cloth. Those same cholesterol raising compounds shouldn't be produced since they're steeped in cold water for an extended period of time (20hrs minimum is pretty standard) but even if they did, the bag would be acting the same as a paper filter for drip coffee and prevent those chemicals from making it into the final product.

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u/thegooddoktorjones 17d ago

My wife does it at home in a French press, I believe the water is hot when initially added, then pressed down then it rests in fridge for a day. No cloth or filter, just the press. Not an expert on it though.

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u/DessertTwink 17d ago

That would no longer be cold brew, then. That's just iced coffee. A strong iced coffee since she's letting it sit, but still iced coffee. The cold water extracts the caffeine and flavor from the coffee beans differently than if you hit it with hot water first. Cold water-only produces a less acidic brew with a smoother flavor.

It's like using softened butter vs melted butter when making cookies. The latter results in a thinner chewy cookie, while the former will be pillowy and lighter in texture. Same ingredients, but the result is different.

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u/Anand999 17d ago

Hot bloom cold brew is definitely a thing. You use just enough hot water to saturate the grounds, then fill the rest of the way with cold water and do the regular long steep time.

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u/Safe-Particular6512 17d ago

Cold brew coffee is started with cold water - Not hot.

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u/iiooxxiiooxx 17d ago

I would also like to know.

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u/telerabbit9000 17d ago

diterpenes

So are these diterpenes "essential and life-giving" or are they "deleterious and poisonous to human life"?

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u/heteromer 17d ago

Neither. They appear to have some antiinflammatory properties but studies have shown the two diterpenes increase LDL cholesterol, which is a marker for cardiovascular disease.

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u/telerabbit9000 16d ago

So, is a French press like a loose hand grenade?

Should I get rid of it immediately?

Also, how does a paper filter magically eliminate these dissolved chemicals?

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u/heteromer 15d ago

They're most likely not dissolved. They're very lipophilic molecules.

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u/FriendlyDisorder 16d ago

Brief reading online says diterpenes are a wide variety of compounds, and some help reduce inflammation or have been shown to attack cancer cells.

Apparently some can elevate cholesterol levels, too? That makes me wonder how much my coffee consumption is contributing to my own elevated cholesterol levels.

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u/Sethjustseth 17d ago

I already posted this, but it's relevant to your question: All I know is I had high cholesterol and one of the many steps I took was going from French press to paper filtered pour over coffee and I saw a 40% cholesterol reduction in 7 months. I'm sticking with filtered coffee.

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u/vadan 17d ago

I saw similar cholesterol reduction within 3 months and all I did was pour the French pressed coffee through a paper filter after the steep.

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u/[deleted] 17d ago

[deleted]

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u/mattcraft 17d ago edited 17d ago

I'm not the commenter who you were asking, but there was previous information that unfiltered coffee was potentially more carcinogenic than paper-filtered coffee. There are flavor/aroma pros and cons as well, but I'm too casual to speak to that. Point being is that I heard this information from at least two co-workers years before coming upon this post now. It pushed me toward using the aeropress instead of french press (although one of the co-workers mentioned adding a paper filter to the french press).

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u/Aquaintestines 17d ago

Bought and paid for by Big Filter

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u/vadan 17d ago

This research isn’t new. Cafestol and its effect has been known about for some time. I just googled for things that can elevate or control cholesterol.

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u/Ascendancy09 17d ago

Also not the original poster, but I had unexpectedly high LDL cholesterol levels and looked at my habits and realized the numbers started climbing when I started making a daily espresso. Google rabbit hole led me to switch to green tea (among a few other changes) and dropped my LDL numbers 50 points in 1.5 months.

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u/quackerzdb 17d ago

That's a huge change. Did you also start taking statins at the same time? 40% is about what you get from standard cholesterol medication.

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u/Sethjustseth 17d ago

Nope, I'm already vegetarian and exercise daily, but I cut way down on cheese, butter, and chocolate, switched to fat free yogurt, cut out palm oil from peanut butter etc., filtered my coffee, and just trying to keep the saturated fat under 10 grams a day if possible. LDL went from 156 to 96 which my doctor called extremely impressive. Glad I don't need medication yet!

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u/randylush 17d ago edited 17d ago

I cut way down on cheese, butter, and chocolate, switched to fat free yogurt, cut out palm oil from peanut butter etc., filtered my coffee,

Given those other massive changes I’m not sure how much you can realistically attribute your lowered cholesterol to filtered coffee

I’m curious though, did you start filtering coffee with the intention of lowering LDL? Was that something a doctor told you to do? Was this link widely known?

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u/Sethjustseth 17d ago edited 17d ago

I know that changing the coffee filter was a tiny change that couldn't have affected my cholesterol much, but I really wanted to try my best in between cholesterol tests to see if diet alone could get me in the healthy range. I have some genetic predisposition to cholesterol which has always been treated with medication in my family.

I got the idea to switch to filtered coffee from this study released in 2020 which was big at the time and stayed in my mind over the years. The cholesterol test finally gave me a reason to change.

https://academic.oup.com/eurjpc/article/27/18/1986/6125530

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u/Emberwake 17d ago

I'm not saying it's a bad idea, but the cholesterol difference between filtered and unfiltered coffee is orders of magnitude less than the impact of reducing your butter and cheese intake by 10%.

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u/quackerzdb 17d ago

That is really impressive. The studies I've seen only see about 10% reductions from diet alone, but you seem very committed and disciplined. Good on you.

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u/p4rk_life 17d ago

You are correct, dietary sourced cholesterol is only a small factor, nick norowitz has several studies and videos explaining the mechanism recently discovered. His 720 eggs or oreos lower ldl are the most popular, but the science behind the process illustrate dietary cholesterol is moderated by a chemical feedback mechanism

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u/Igotdaruns 17d ago

Are you as happy though?

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u/Sethjustseth 17d ago

Yes, very! I have two young children and I want to be around for them as long as possible in the best physical shape possible. That's my #1 priority. I still eat what I want, just in moderation.

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u/Igotdaruns 16d ago

What do you eat in a day? Do you still have urges or splurges related to food? I’m in a similar boat and am trying to right a sinking ship as well.

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u/Sethjustseth 16d ago

One easy change I made was switching to fat-free yogurt. I have two young children in the house so we have a lot of full fat dairy products and instead of buying duplicates I was eating that, which was a bad idea.

For breakfast I usually have yogurt, blueberries, and granola or overnight oats. For lunch it's usually leftovers or peanut butter and jelly sandwich in a banana, or instant ramen noodles or something, and for dinner we put in more work and make stir fries, fried rice, pasta, pizza, sushi, etc.

I used to eat way too much chocolate for snacks, so now I'll just have like a couple small pieces. And cheese has always been a favorite where I could eat several ounces at a time, so I switched to eating just a single low-fat string cheese when I get the urge. The difference is 1.5 g of saturated fat versus 4.5 g per slice. When the family wants to go out for ice cream I'll have a taste of the ice cream, but if I'm going to get my own I'll get a sorbet which I like quite well anyhow.

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u/t_thor 17d ago

Damn I love my unfiltered pour-overs :(

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u/timetofocus51 17d ago

Can't you just paper filter pour your french press coffee for the same effect?

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u/Sethjustseth 17d ago

Yep, you could. Pour over has a different flavor profile because it's not submersed like the French press and I've come to like it quite well. My first coffee love was Vietnamese using the pour over phin filter. So many different types of coffee.

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u/squad1alum 17d ago

Among the poorest at filtering out the mentioned cholesterol raising substances.

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u/BrownByYou 17d ago

What if you made it in a French press but then poured it through the white filter paper we use in machines?

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u/JksG_5 17d ago

It will likely reduce the amount of substances.

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u/systoll 17d ago

Aeropress coffee is exactly that, if you want to streamline the process.

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u/Mechasteel 17d ago edited 17d ago

The French press has a roughly 10x reduction, and paper-filtered coffee a 78x reduction, vs boiled unfiltered coffee.

...estimated LDL cholesterol to increase 0.0104 mmol/L per mg cafestol, and 0.0016 mmol/L per mg kahweol daily ingested. [...] The median (range) cafestol and kahweol concentrations were 176 (24–444) mg/L and 142 (18–434) mg/L for brewing machines (n = 11), 8 (2–343) mg/L and 7 (2–288) mg/L for liquid-model machines (n = 3), and 12 (4–24) mg/L and 8 (3–19) mg/l for home-brewed, paper-filtered coffees (n = 5). Boiled coffee had high concentrations of cafestol and kahweol, 939 mg/L and 678 mg/L, but having it poured through a fabric filter reduced the concentrations to 28 and 21 mg/L. Other coffee brews (percolator, French press) contained intermediate levels of cafestol (∼90 mg/L) and kahweol (∼70 mg/L), with the exception of some espresso samples with high levels (up to 2447 mg/L cafestol).

Per these numbers, 270 ml (9.5 Oz) boiled unfiltered coffee would raise your LDL by 102 mg/dL, enough to go from zero to too much. Espresso and its variants are comparable to boiled unfiltered coffee, in terms of diterpenes to caffeine ratio.

[edit:] there's a 100x variance in the sample ranges, probably relating to whether there is a filter.

[edit:] this is one of the most understated headlines I've seen, with a single cup having enormous health implications, and the trivial solution of passing it through a 1 cent paper filter.

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u/RAPEBERT_CUNTINGTON 17d ago

this is one of the most understated headlines I've seen, with a single cup having enormous health implications,

What? A single cup isn't adding 500mg of LDL to your body. It literally says "daily", as in someone who drinks this every single day of their life. Also, the source they quote about 0.014mmol/L per 1mg cafestol says those figures come from a study where the cafestol was suspended in oily solutions and swallowed, not consumed as coffee: https://journals.sagepub.com/doi/epdf/10.1177/014107689608901107

The actual studies where 20+ people had on average EIGHT cups (56g of beans) of either boiled or filtered coffee per day "only" showed a 30mg/dL increase in cholesterol with the boiled coffee. Yeah it's significant and bad, but it's nowhere close to the theoretical 102mg/dL from a single cup you propose.

I really doubt how accurately they sampled everything considering the insane variation between samples, and how closely their "boiled coffee" match how it's actually made and consumed. They boiled it with grounds for 3 minutes and then steeped it. Literally everyone I know boils the water, takes it off the heat to add grounds, and just let it steep until the grounds sink. They also stored it in a freezer for up to 4 weeks before analysis. Most of the compounds in unfiltered coffee likely come from suspended bean particles. How does the freezing affect the particles and the oils in the particles?

Extrapolating that a cup has "enormous health implications" from a short study with a microscopic sample size and unconfirmed assumptions is crazy.

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u/Mechasteel 17d ago

The variation is in line with the difference filtration makes (roughly 100x for paper filter, 30x for cloth, 10x for metal mesh). In real life the oils might also stick to the grounds, the cup, or any fiber in your diet.

It does seem suspicious that their boiled coffee has so much cafestol, but some of the espresso samples have even more (and those they collected from caffeterias and workplaces). I'd definitely want to verify that the variance in espresso machines relates to having a filter or not.

The cholesterol number I got from just blindly multiplying out the numbers. If the cafestol in boiled coffee isn't 10-100x larger than other brewing methods then that calculation will also be wrong.

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u/digno2 17d ago

what about the freeze dried instant coffee?

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u/alien_ated 17d ago

But don’t the French have surprisingly good cholesterol levels despite their consumption copious butter and cheese?

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u/earthsworld 17d ago

sorry, but are you imagining that everyone in France uses a french press?

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u/alien_ated 17d ago

No but their other preferred methods of coffee preparation also don’t involve paper filters. As others have pointed out, machine-made coffees are popular in France as well.

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u/GeraldoDelRivio 17d ago

Well obviously. I mean what next? Are you going to tell me French fries aren't a staple of their cuisine? Preposterous!

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u/Pianopatte 17d ago

Maybe because the eat less highly processed food that contains trans fats and such?

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u/redcoatwright BA | Astrophysics 17d ago

That and they/all of Europe doesn't have the car culture we do, people walk way more frequently and on average much more. When your grocery store is a 5 minute walk, and your work is a 10m walk (with good public transit) and your friends are 10m away walking or on public transit, you just tend to walk way more often.

Source lived in Geneva for a year (actually I moved from Geneva to Sergy but similar non car culture even though Sergy is arguably almost rural).

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u/Any_Following_9571 17d ago

one of the thousand reasons. r/fuckcars

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u/Why_You_Mad_ 17d ago

Does anyone even eat trans fats anymore? They’re practically extinct even in processed foods.

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u/olivemartinis 17d ago

It’s in partially hydrogenated oils in most processed junk food. In the US, labels can claim 0% trans fats if the total is under 0.5 grams per serving, so it can add up

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u/Eragaurd 17d ago

Butter has a few percent of trans fats, so you can get it from there.

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u/DervishSkater 17d ago

So it’s almost like coffee consumption isn’t the problem

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u/Pianopatte 15d ago

Well, you have to look at the whole picture. If you have a diet thats rich in cholesterol and unhealthy fats then switching to filtered coffee may make a difference.

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u/OPtig 17d ago

I never saw anyone use a French press when I lived in France. It was espresso at restaurants and at home people were using Nespresso or some other pod.

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u/tenebrigakdo 17d ago

Cheese is according to some metastudies a small positive for cholesterol levels, it may lower them slightly.

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u/Novaskittles 17d ago

I always thought that the cheese eating habits of the French were exaggerated, but then I became friends with a Frenchman. He regularly shows me pictures of his sandwiches, which are just a pile of various soft cheeses melted between two slices of bread.

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u/ewillyp 17d ago

i just ate lunch and you made my tummy curious.

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u/vitringur 17d ago

Perhaps you are just wrong about what makes food healthy

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u/alien_ated 17d ago

Did I say anything about healthy?

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u/sionnach 17d ago

Not all cholesterol is bad. Guess what sort of foods the really bad type comes from?

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u/Vesploogie 17d ago

They eat better quality, more nutritious foods, are more active, and generally aren’t as fat as most Western countries. That’s the difference maker, not a cup of coffee.

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u/vadan 17d ago

It’s just as bad but you can just pour it through a paper filter after pressing and retain the taste and filter out most of the cafestol. 

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u/Glittering_Cow945 17d ago

Thats how they found out 30 or 40 years ago. A Dutch researcher published her findings that coffee had a cholesterol raising effect only in countries that regularly make french press coffee, namely Scandinavia. This led to the discovery of kahweol and cafestol. This is not a new finding. It has been known for decades.

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u/edwmoral 17d ago

My doctor banned french press due to my high cholesterol

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u/o793523 17d ago

French press raised my LDL significantly. I switched to paper filters and it dropped back down

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u/squi993 17d ago

If it is not filtered through paper it will contain the oils that give you higher cholesterol, they have a drug like effect.

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u/deja-roo 17d ago

You could just click the link and read it?

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u/[deleted] 17d ago

With some slight rigging, you can fit a filter paper into a French press, this achieving all of the benefits.

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u/Cicer 17d ago

Is it filtered through paper?  Well you’ve got your answer. 

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u/Mozambique_Sauce 17d ago

Does the french media have it's own type of coffee?