Coffee makes the world go round. For millions of people out there, there’s no morning without coffee. But not all cups are created equal. There’s the espresso, the French press, the bottomless pot, and a bunch of other types of coffee. According to a new study, some of those are worse for your health than others.

The study found that coffee brewed in common workplace machines — especially those using metal filters — contains significantly higher levels of the cholesterol-raising compounds cafestol and kahweol than paper-filtered coffee. In other words, if you care about cholesterol, filtered coffee may just be the healthiest option out there.

It’s not the bean, it’s how you make it

Coffee is a complex beverage. It’s packed with biologically active compounds. Some are protective — like antioxidants. Others are energizing — like caffeine. But two molecules in particular, cafestol and kahweol, carry a darker side. These oily substances can raise LDL cholesterol, the kind that builds up in arteries and contributes to heart disease.

Here’s the catch: cafestol and kahweol aren’t removed by roasting, grinding, or bean selection. They’re in all coffee. But whether they end up in your cup depends entirely on the brewing method.

“We studied fourteen coffee machines and could see that the levels of these substances are much higher in coffee from these machines than from regular drip-filter coffee makers. From this we infer that the filtering process is crucial for the presence of these cholesterol-elevating substances in coffee. Obviously, not all coffee machines manage to filter them out. But the problem varies between different types of coffee machines, and the concentrations also showed large variations over time,” says David Iggman, researcher at Uppsala University, who led the study.

Paper filters — like those used in drip coffee makers — trap most of these compounds. But brewing methods without a fine filter let them slip through. That includes French press, espresso, boiled coffee, and many workplace machines. Simply put, any type of coffee that doesn’t include a filter is likely adding cholesterol to your brew.

Filtered coffee is a quiet hero

Filtered coffee is usually not the most popular choice. Even people who do drink filtered coffee don’t usually think about filters beyond whether they’re biodegradable or fit their machine. But these filters act like tiny health guardians. They trap diterpenes (a class of compounds that includes cafestol and kahweol) before they can enter your bloodstream.

Even makeshift filters — like a double-layered polyester sock — proved effective in the lab. It’s not the sophistication of the machine that matters. It’s the presence of a fine enough barrier. The type of bean also didn’t seem to matter much. The difference is how you make your coffee, not what the coffee is like.

This is one reason why the Nordic Nutrition Recommendations now specifically endorse filtered coffee over unfiltered. Nordic countries love their coffee and opting for filtered was considered a public health move, not a flavor crusade.

Coffees from brewing machines — common in hospitals and offices — contained up to 444 mg/L of cafestol. In contrast, paper-filtered coffee came in at just 12 mg/L. That’s more than a 35-fold difference. Espresso was even worse in some cases, with one sample topping 2,400 mg/L. Some espresso samples in the study had moderate diterpene levels. Others were off the charts. The variation likely comes down to differences in pressure, temperature, grind size, and machine cleanliness. But because espresso doesn’t use a paper filter, the risks remain.

What this all means

The researchers ran simulations based on average coffee consumption — about three cups per workday. Over time, switching from high-diterpene machine coffee to filtered drip coffee could reduce LDL cholesterol by 0.58 mmol/L.

That might sound minor. But over the course of 5 years, this translates to a 13% reduction in heart disease risk, thanks to less plaque buildup in arteries​; over 40 years, it’s a 36% reduction, the researchers note. In public health terms, that’s a massive gain from a modest change. It’s like adding full-fat cream to each cup of filtered coffee. You might not taste it, but your heart notices.

This could also explain some of the uncertainty regarding the health effects of coffee. Over the decades, science has struggled to make sense of coffee’s health effects, even though coffee is among the most studied beverages on Earth. One study says it’s good for your brain. Another links it to longer life. But then come warnings about cholesterol, high blood pressure, and even heart disease. For every headline declaring coffee a superfood, another whispers caution. A part of this could be explained by how coffee is made; as researchers showed, even the same type of coffee (ie an espresso) can sometimes have very different cholesterol values.

“Most of the coffee samples contained levels that could feasibly affect the levels of LDL cholesterol of people who drank the coffee, as well as their future risk of cardiovascular disease. For people who drink a lot of coffee every day, it’s clear that drip-filter coffee, or other well-filtered coffee, is preferable,” says Iggman.

How to make a healthy coffee

The way you make your coffee matters — a lot more than most people realize. A simple paper filter can intercept cholesterol-raising compounds and potentially lower your long-term risk of heart disease.

If you’re reading this and wondering whether you should switch to filtered coffee, the answer is probably ‘yes’. This isn’t the first study to come up with this conclusion and there seem to be only upsides to filtered coffee. Filtered coffee continues to show health benefits—or at least neutrality. Unfiltered coffee, on the other hand, is consistently linked to higher cholesterol and, in long-term studies, increased heart disease and mortality​.

The good news is that this should be fairly easy and inexpensive to do. Here are some basic tips to follow:

• Brew coffee using paper filters, either in a drip machine or pour-over.
• Avoid regular use of metal-filtered methods like French press, moka pot, or percolator.
• Be cautious with espresso, especially in high quantities.
• At work, find out what kind of machine you’re using. If it’s a metal-filtered brewing system, consider alternatives — or bring your own filtered brew.

Your heart — and your future self — will thank you.

The study was published in the journal Nutrition, Metabolism, and Cardiovascular Diseases.