What are cafestol and kahweol?

Cafestol and kahweol are two lipid diterpenes naturally present in coffee bean oils. They are the only known dietary compounds that increase LDL cholesterol in a dose-dependent and measurable way. Their impact depends entirely on preparation method: a paper filter retains 97 to 99 % of these compounds and practically eliminates their effect on cholesterol; unfiltered preparations (French press, boiled coffee, espresso without paper filter) release them fully into the cup.

Cafestol and kahweol belong to the diterpene family — hydrophobic lipid molecules found primarily in the oily fraction of coffee beans. They are present in both Arabica and Robusta, albeit in slightly different proportions. Their discovery as hypercholesterolaemic agents dates to the 1990s, through Dutch research that had noticed cholesterol increases in countries where boiled coffee (Scandinavian kaffekoker or Turkish coffee) was prevalent.

The mechanism of action of cafestol is well elucidated. It inhibits a nuclear receptor in the liver called FXR (Farnesoid X receptor), a key regulator of bile acid metabolism. By disrupting this system, cafestol reduces the liver's capacity to clear LDL-cholesterol from the bloodstream, causing it to accumulate. Controlled studies have shown that consuming French press coffee at 4 cups per day for 4 weeks can increase LDL-cholesterol by 6 to 10 % — a clinically significant shift.

Kahweol acts through a complementary mechanism but shares the same lipid regulatory pathways. Recent studies also attribute anti-carcinogenic properties to it in certain cell models, notably for liver and colon cancers, by inhibiting phase II enzymes of xenobiotic metabolism. These potentially beneficial properties of kahweol illustrate the complexity of coffee's health profile: the same compound can be detrimental for cholesterol but potentially protective against other pathologies.

Practical impact is entirely determined by filtration method. Paper filter is the only one that effectively retains cafestol and kahweol: its micropores (0.3 to 0.5 mm) block the oil droplets containing these diterpenes. Metal filters (used in French presses, Mokas, some espressos) let the oils pass through. Cloth filters (used in Portuguese and Brazilian traditions) have intermediate efficacy.

Quantitatively, one espresso contains on average 2 to 4 mg cafestol, one French press cup 4 to 7 mg, one cup of Scandinavian boiled coffee 7 to 10 mg, and one paper-filtered cup less than 0.5 mg. For a consumer with cardiovascular risk or under lipid monitoring, these values are clinically relevant: 4 cups of French press per day — 16 to 28 mg cafestol — can cause an LDL increase of 0.13 to 0.25 mmol/L over several weeks.

Espresso deserves special mention: although prepared without paper filter, the very small cup volume (25–30 ml) means the absolute amount of cafestol ingested per serving remains relatively low compared to a large French press cup. One or two espressos per day therefore presents a more limited risk than several large plunger coffee cups.

Cafestol content by preparation method