The Shocking Link Between Office Coffee and Heart Health

“Considering how much coffee is consumed in Swedish workplaces, we wanted to get a picture of the content of cholesterol-elevating substances in coffee from these types of machines. 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,” says David Iggman, researcher at Uppsala University, who led the study.

“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,” Iggman continued.

First Study on Office Coffee Machines

It’s already well known that boiled coffee contains high levels of the cholesterol-raising diterpenes cafestol and kahweol. A fact acknowledged in the latest Nordic nutrition guidelines, which recommend limiting boiled coffee. In contrast, drip-filter coffee makers that use paper filters are highly effective at removing these substances.

How well conventional coffee machines, which are found in public environments such as workplaces, filter out these substances had not been investigated up until now. In the study, the researchers studied fourteen coffee machines in break rooms at different workplaces. The coffee used was five regular brands of ground coffee. They took samples from the coffee made by the machines on a number of separate occasions and analyzed the contents. There was a big difference between the machines in terms of the levels of cafestol and kahweol in the coffee they made, but the levels could also differ at different times.

Brewing Machines Showed the Most Risk

The most common type of coffee machine, in the study called a brewing machine, is the one that produced coffee with the highest concentrations of diterpenes. In comparative analyses, the researchers investigated peculator coffee, espresso, French press coffee, boiled coffee, and boiled coffee poured through a fabric filter. The boiled coffee contained the highest levels of diterpenes per cup. Some espresso samples also contained high levels, but there was great variation.

Filtered Coffee Still the Best Bet

“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. To determine the precise effects on LDL cholesterol levels, we would need to conduct a controlled study of subjects who would drink the coffee,” says David Iggman.

Facts in Brief

Two samples were taken from each machine every two to three weeks. The coffee varieties included medium roast and dark roast of five common brands of ground coffee. Most of the machines use ground coffee. One or two grind the beans in the machine, but the researchers don’t think that would have any effect on the levels of diterpenes.

We tested 14 machines, including 11 brewing machines and 3 liquid-model machines (lower levels, mixed from a coffee concentrate). For comparison, the same analysis was carried out with some other coffee-making methods such as percolator, French press, boiled coffee, and boiled coffee poured through a fabric filter. In addition, four espresso samples were collected in Gothenburg.

All the coffee samples were analysed at Chalmers University of Technology. The samples were collected by medical student Erik Orrje during spring 2024.

Reference: “Cafestol and kahweol concentrations in workplace machine coffee compared with conventional brewing methods” by Erik Orrje, Rikard Fristedt, Fredrik Rosqvist, Rikard Landberg and David Iggman, 20 February 2025, Nutrition, Metabolism and Cardiovascular Diseases.
DOI: 10.1016/j.numecd.2025.103933