The Study
Separate effects of the coffee diterpenes cafestol and kahweol on serum lipids and liver aminotransferases.
This study gave people pure coffee chemicals and saw their blood change — so we know those chemicals cause those changes. But it doesn't tell us what happens when you drink regular coffee, because most coffee doesn't have those chemicals in it.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Coffee beans have two natural oils — cafestol and kahweol — that get into your cup if you don’t use a paper filter.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 566 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1A 31 mg/dL cholesterol rise is large — similar to eating extra butter daily — and could increase heart disease risk over time.
- 2Cafestol raised cholesterol by 31 mg/dL and triglycerides by 58 mg/dL.
- 3Kahweol didn’t raise cholesterol much but made liver enzymes go up by 35 U/L.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The American journal of clinical nutrition
Year
1997
Authors
R. Urgert, N. Essed, G. van der Weg, T. Kosmeijer-Schuil, M. B. Katan
Related Content
Claims (6)
Cafestol in unfiltered coffee raises cholesterol and triglycerides more than any other compound in coffee, including kahweol, which has a much smaller effect.
Cafestol and kahweol raise alanine aminotransferase levels in the liver through mechanisms that are separate from how they affect blood lipid levels.
Consuming 61-64 milligrams of cafestol daily for 28 days raises total serum cholesterol by 0.79 mmol/L, LDL cholesterol by 0.57 mmol/L, fasting triacylglycerols by 0.65 mmol/L, and alanine aminotransferase by 18 U/L in healthy adult males.
Adding kahweol to cafestol raises a liver enzyme called alanine aminotransferase by 35 U/L without changing serum lipid levels.
Unfiltered coffee raises blood lipids and liver enzyme levels because of cafestol, a compound removed by coffee filters; kahweol contributes little to lipid increases but significantly to liver enzyme increases.
People who drink unfiltered coffee have higher LDL cholesterol levels than people who drink filtered coffee.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.