Coffee is one of the world’s most beloved beverages, fueling workdays and energizing mornings for millions. Yet, new scientific findings suggest that how your coffee is brewed might impact your health more than you realize — particularly when it comes to cholesterol.
A recent study led by researchers in Sweden has uncovered that on-demand coffee machines, the kind now common in many workplaces and offices, may significantly raise levels of “bad” cholesterol in the body.
The culprit? A group of natural oils found in coffee beans called diterpenes, which can affect blood cholesterol levels based on how the coffee is prepared.
Diterpenes: The Cholesterol-Raising Compounds in Coffee
The oils in coffee beans are rich in compounds known as cafestol and kahweol. As far back as the mid-20th century, scientists discovered that unfiltered coffee contains enough of these substances to meaningfully raise low-density lipoprotein (LDL) cholesterol, often labeled as “bad” cholesterol, while slightly reducing the more favorable high-density lipoprotein (HDL) cholesterol.
Subsequent research showed that these diterpenes are significantly reduced when coffee is brewed using a paper filter. Methods like boiling or using a French press, which leave these oils in the beverage, maintain high levels of these compounds. What hadn’t been extensively studied until now, however, was the coffee coming from the increasingly popular workplace coffee machines.
“Coffee from workplace machines, however, had not been examined until now,” says study author David Iggman, PhD, a researcher at Uppsala University in Sweden.
“We found the levels of these substances are much higher in coffee from these machines than from regular drip-filter coffee makers,” Dr. Iggman adds.
The Study: Measuring Diterpenes Across Brewing Methods
To gather data, Dr. Iggman and his team examined 14 different types of conventional office coffee makers. The two primary kinds were machines that brewed coffee by mixing hot water with ground beans and filtering it through a metal screen, and those that mixed hot water with a liquid coffee concentrate.
For comparison, they also tested coffee made with more traditional methods — paper-filtered drip coffee, percolators, French presses, and even the old-fashioned Swedish method of boiling ground coffee beans with water. Additionally, four espresso samples were analyzed from three cafeterias and a laboratory coffee machine.
Unsurprisingly, the study confirmed that paper-filtered coffee had the lowest levels of diterpenes, while espresso and boiled coffee had the highest. Most strikingly, however, was the discovery that many workplace brewing machines produced coffee with far higher levels of cafestol and kahweol than standard paper-filter coffee.
Ranking Coffee Brewing Methods by Cholesterol Impact
Researchers measured diterpene concentrations in milligrams per liter (mg/L). The median levels for cafestol and kahweol in workplace coffee machines reached 174 and 135 mg/L, respectively — far exceeding the 11.5 mg/L and 8.2 mg/L found in paper-filter drip coffee.
French press and percolator methods fell somewhere in the middle, while espresso and boiled coffee topped the charts with concentrations exceeding 1,000 mg/L in some cases. However, espresso showed surprising variability, with cafestol levels ranging dramatically from 35.6 to 2,446.7 mg/L, for reasons the researchers couldn’t fully explain.
“Keeping espresso to a minimum will lower risks,” says Melissa Prest, DCN, RDN, a spokesperson for the Academy of Nutrition and Dietetics, who was not involved in the study. She advises limiting espresso to one or two shots per day.
When ranked in terms of their potential effect on cholesterol, coffee brewing methods came out in the following order:
- Paper filter
- Filtered boiled
- French press
- Workplace coffee machine
- Percolator
- Boiled without filtering
- Espresso
Are These Cholesterol Risks Linked to Heart Disease?
While this study paints a detailed picture of how different brewing methods affect diterpene content, it stops short of making direct claims about cardiovascular health risks. Gregory Katz, MD, a cardiologist at NYU Langone Heart, points out a critical limitation.
“They certainly didn’t test different brewing methods and then see how that impacted things like heart attack and stroke,” says Dr. Katz. “The study tells us zero information about how this impacts the risk of cardiovascular disease.”
The Full Picture: Coffee’s Health Benefits and Trade-Offs
Interestingly, while cafestol and kahweol can elevate LDL cholesterol, they also bring health benefits. “The benefits of these two substances with regular consumption of coffee includes anti-inflammatory properties and its links to reducing the risk of type 2 diabetes,” says Julia Zumpano, RD, with the Cleveland Clinic Center for Human Nutrition.
Coffee is packed with other valuable compounds too — including micronutrients like B vitamins, potassium, and magnesium, as well as antioxidants that combat cellular damage. Phenols, another group of chemicals found in coffee, help protect the body from inflammation and bolster the immune system. And, of course, caffeine itself has been linked to improved brain function, blood flow, and even blood pressure regulation in moderate doses.
The Bigger Threat Might Be What You Add to Your Cup
Interestingly, many health experts suggest that the sugar, cream, and other additives people often stir into their coffee may pose an even greater health risk than diterpenes.
“Both excess added sugar and saturated fat found in high fat dairy products like cream adversely affect cardiovascular health,” says Maya Vadiveloo, PhD, RD, chair of the American Heart Association’s Lifestyle Nutrition Committee.
She emphasizes that while moderate coffee consumption is generally safe and potentially beneficial, filtering it when possible can help reduce cholesterol risks.
Final Thoughts: Filtering for Health
In light of these findings, coffee lovers — particularly those relying on office machines or indulging in multiple espressos daily — might consider switching to paper-filtered brews when possible. While the study doesn’t directly measure long-term heart outcomes, lowering diterpene intake could be a smart move for individuals concerned about cholesterol.
As research continues to uncover the complex health implications of coffee, one thing remains clear: how you brew it matters.
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