“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.”
Based on their results, Dr. Iggman and colleagues estimated that replacing three cups of brewing-machine coffee with paper-filtered coffee five days per week could lower LDL cholesterol by 13 percent over five years, or 36 percent over 40 years.
Paper Filters May Make a Difference
For the analysis, the study authors measured two kinds of diterpene — cafestol and kahweol — in coffees made in 14 different types of conventional self-serve coffee makers found in break rooms and different work spaces.
Coffee samples were taken from two types of office machines:
- Machines that mixed hot water with the ground coffee and then passed the liquid through a metal filter
- Machines that mix a liquid coffee concentrate with hot water
For comparison, the researchers also analyzed samples of coffee made with a paper filter, a percolator, and a French press, as well as by coffee made by boiling ground beans with water (a method popular in Sweden).
In addition, they examined four espresso samples made in three cafeterias and one laboratory workplace coffee machine.
They discovered that most coffees from workplace brewing machines contain higher diterpene concentrations than paper-filtered coffee.
Ranking Brew Styles From Best to Worst
The researchers measured diterpenes in terms of milligrams per liter (mg/L). For all workplace coffee machines, the median range of cafestol and kahweol was 174 and 135 mg/L, respectively, compared with 11.5 mg/L of cafestol and 8.2 mg/L for kahweol in paper-filter drip coffee.
Diterpene concentrations in French press (87 mg/L cafestol and 69 mg/L kahweol) and percolator coffee (91 mg/L cafestol and 69 mg/L kahweol) fell in the middle between coffee machine and paper filter levels.
Boiled coffee (939 mg/L cafestol and 678 mg/L kahweol) and espresso (1,059 mg/L cafestol and 621 mg/L kahweol) had the highest diterpene content. The study authors noted, however, that there was considerable and “unexplained” variation in espresso samples with cafestol levels ranging from 35.6 to 2,446.7 mg/L.
Because espresso is made by forcing hot water through very finely ground coffee under high pressure without a filter, it makes sense that this brew has the highest potential to raise cholesterol levels.
“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 recommends limiting espresso to one or two shots per day at most.
Overall, coffee brew styles ranked as follows in order of best to worst for cholesterol are:
- Paper filter
- Filtered boiled
- French press
- Workplace coffee machine
- Percolator
- Boiled without filtering
- Espresso
Study Does Not Address the Impact on Heart Disease Risk
For Gregory Katz, MD, a cardiologist at NYU Langone Heart in New York City, these study results are limited in that experiments were not conducted to see the actual impact on LDL levels or endothelial function (the functioning of cells that line the inside of blood vessels).
“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.”
Coffee Has Many Health Benefits
- Micronutrients like vitamin B2 and B3, potassium, and magnesium
- Antioxidants, which protect cells from damage and may lower the risk of certain cancers
- Phenols, which play key roles in immunity and protecting the body from inflammation
- Caffeine, which may offer potential support for brain health, blood flow, and blood pressure.
Coffee Add-Ins May Pose a Higher Risk Than Coffee Itself
Maya Vadiveloo, PhD, RD, chair of the American Heart Association’s Lifestyle Nutrition Committee and an associate professor of nutrition and health sciences at the University of Rhode Island in Kingston, suggests that the ingredients we add to coffee may be more damaging than the coffee itself.
“Both excess added sugar and saturated fat found in high fat dairy products like cream adversely affect cardiovascular health,” says Dr. Vadiveloo, who was not involved in this study.
She advises consumers to drink coffee in moderate amounts, but filter it whenever possible to reduce the risk of elevated LDL cholesterol.