Occupational hazard: Most office coffee machines leach cholesterol-elevating compounds, study flags

Researchers are warning that coffee made in most of the coffee machines found in workplaces contains relatively high levels of the worst cholesterol-elevating substances. Regular paper filter coffee makers filter out most of the substances, which machines do not. 

The recent study was led by Uppsala University, Sweden, in collaboration with Chalmers University of Technology.

“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,” says lead author David Iggman, a researcher at Uppsala University.

“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,” he explains. “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.”

The findings are published in the journal Nutrition, Metabolism & Cardiovascular Diseases.

Paper option for effective filtration

Previous research has already found that boiled coffee in a pot contains high levels of cholesterol-elevating substances — the diterpenes cafestol and kahweol.

Regular paper filter coffee makers filter out most of the cholesterol-elevating substances, which machines do not.

Regular paper filter coffee makers filter out most of the substances, which machines do not. 

This is even mentioned in the latest Nordic nutritional recommendations, which advise reducing or refraining from drinking boiled coffee. However, the study authors add that a regular drip-filter coffee maker, which uses a paper filter, almost completely filters out these cholesterol-elevating 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,” they underscore.

The researchers studied fourteen coffee machines in break rooms at different workplaces in Spring 2024, most of which used ground coffee. They tested 14 machines, including 11 brewing machines and three liquid-model machines based on coffee concentrates.

The study focused on five regular brands of ground coffee, with two samples 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.

One or two of the break rooms grind the beans in the machine, but the researchers don’t believe that would have any effect on the levels of diterpenes.

The study pinpointed a significant difference between the machines in terms of the levels of cafestol and kahweol. However, these levels could also differ at different times.

Worst method of producing coffee

The most common type of coffee machine in the study, called a brewing machine, produced coffee with the highest concentrations of diterpenes.

The most common type of coffee machine in the study, called a brewing machine, 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.

Boiled coffee contained the highest levels of diterpenes per cup. Some espresso samples also contained high levels, but there was great variation, note the study authors.

“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.

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

The study findings contrast previous research that reveal coffee lowers cholesterol, although it remains unclear how the two outcomes influence each other.