What’s the healthiest way to brew a fresh cup of coffee? A landmark study exploring coffee brewing methods and their links to heart attacks and mortality has determined that filtered coffee is the safest option.
"Our study provides strong evidence linking coffee brewing methods to heart attacks and longevity," says Professor Dag S. Thelle from the University of Gothenburg, Sweden, the lead author. "Unfiltered coffee contains substances that raise blood cholesterol levels. A simple filter removes them, lowering the risk of heart attacks and premature death."
Coffee remains one of the world’s most beloved beverages and stimulants. Three decades ago, Professor Thelle discovered that coffee consumption correlated with higher total and LDL ("bad") cholesterol, potentially harming heart health. Lab tests pinpointed the cholesterol-raising compounds—oils like cafestol and kahweol—and showed filters effectively remove them. Unfiltered coffee holds about 30 times more of these lipids than filtered varieties.
"We investigated whether this cholesterol impact translated to more heart attacks and heart disease deaths," Professor Thelle explains. "Randomized trials forcing coffee abstinence would be unethical, so we launched a large population study with results spanning decades."
From 1985 to 2003, the research enrolled 508,747 healthy Norwegians aged 20-79—a representative sample. Participants reported coffee intake and type via questionnaire, with data adjusted for confounders like smoking, education, exercise, BMI, blood pressure, and cholesterol.
Over an average 20-year follow-up, 46,341 participants died, including 12,621 from cardiovascular disease and 6,202 from heart attacks.
Coffee drinking overall posed no danger. Filtered coffee outperformed abstaining: it linked to a 15% lower all-cause mortality risk. For cardiovascular death, risks dropped 12% in men and 20% in women versus no coffee. Optimal benefits appeared with 1-4 cups of filtered coffee daily.
"Filtered coffee drinkers fared slightly better than non-drinkers, independent of age, gender, or lifestyle," Professor Thelle notes. "This holds true after rigorous analysis."
Filtered coffee also outperformed unfiltered for all-cause, cardiovascular, and heart attack mortality—largely due to unfiltered’s cholesterol effects, per the study.
Unfiltered coffee didn’t raise death risk overall versus abstinence, except in men over 60, where cardiovascular mortality rose.
"We captured coffee habits once, but Norwegian brewing shifted toward filters during follow-up," Professor Thelle says. "Younger people and women likely switched, weakening associations, while older men stuck to unfiltered."
Though observational, Professor Thelle’s advice to health authorities: "If you have high cholesterol, avoid unfiltered brews like French press. Everyone else: Enjoy filtered coffee with confidence."
