Other findings showed similar increases in total cholesterol for both sexes from boiled or plunger coffee, as previous research has also suggested, while drinking filtered coffee was linked to increased total cholesterol only for women.
"Coffee is the most frequently consumed central stimulant worldwide, and Norway has the second-highest coffee consumption in the world," wrote the researchers, led by Åsne Lirhus Svatun of UiT The Arctic University of Norway in Tromsø.
"Because of the high consumption of coffee, even small health effects from the popular beverage could have considerable health consequences and is, therefore, an important topic for research," they concluded.
The results were published online Tuesday in the journal Open Heart.
"There have been several studies that showed an association with unfiltered coffee and increases in total cholesterol," says Nieca Goldberg, MD, a cardiologist at NYU Langone Health, who was not involved in the research. "The chemicals that mediate this increase are dipterenes, cafestol and kahweol.”
David Kao, MD, an associate professor of medicine at the University of Colorado School of Medicine, suggests using fewer high-fat dairy products in coffee: "For example, changing to plant-based substitutes might be helpful if whitening coffee is a habit."
He notes that total cholesterol measured in this study includes all types of cholesterol.
"I would also suggest looking at the HDL, which is good, versus LDL, which is bad, rather than just the total in a case like this. If the change is all due to increased good HDL, then that is actually desirable," Kao says.
He also suggests that researchers look at other diet and lifestyle habits linked to coffee consumption, like certain types of meals or excessive fatigue that might suggest another condition like sleep apnea.
"Sometimes the coffee consumption is just a marker of other things," Kao says.
The new analysis included 21,083 people from the Tromsø Study in Northern Norway. The average age of the group was 56.4 years. The researchers evaluated the relationship between each level of coffee drinking and serum total cholesterol levels and looked at the effect of gender on these findings. The reference group was made up of those who did not drink coffee.
Drinking 3 to 5 cups of espresso each day was significantly linked to increased total cholesterol levels for men and women, compared to those who did not drink espresso.
Drinking 6 or more cups of plunger/boiled coffee each day was also linked with greater serum total cholesterol for men and women, compared with people who did not drink any coffee prepared this way.
The researchers also found that for women, drinking 6 or more cups of filtered coffee each day was linked with total cholesterol levels, but this increase was not found among men.
Drinking instant coffee was associated with higher cholesterol than not drinking instant coffee for both men and women, but there didn't appear to be a relationship with how much instant coffee was consumed, the researcher said.
Limits of the study included self-reporting and the fact that the study consisted primarily of elderly and white middle-aged adults.