Health file · Diterpenes
Metal filters & cafestol
Swapping a paper filter for a metal one changes more than body. It also changes how much of two oily compounds — cafestol and kahweol — reach your cup. Both are linked to higher LDL cholesterol. This page summarises what published research says. It is general information, not medical advice.
What cafestol is
Cafestol is a diterpenoid compound found in coffee beans. Wikipedia cites a range of about 0.4% to 0.7% cafestol by weight in a typical arabica bean. Kahweol is a close relative. Harvard’s Nutrition Source lists “diterpenes including cafestol and kahweol” among coffee’s plant chemicals.
Why it matters
Harvard’s Nutrition Source says unfiltered coffee contains diterpenes that can raise LDL (“bad”) cholesterol and triglycerides. Wikipedia summarises research (Urgert & Katan, 1997) that regular consumption of boiled coffee raises serum cholesterol, while filtered coffee does not, and notes laboratory work suggesting cafestol acts on receptors involved in cholesterol regulation.
How brew method changes the dose
| Method | Diterpene level (as described in sources) |
|---|---|
| Paper-filtered drip | “Almost no diterpenes” (Harvard); negligible because paper retains them (Wikipedia) |
| Instant coffee | “Almost no diterpenes” (Harvard) |
| Espresso | “Moderate amounts” (Harvard); some samples high, with great variation (Uppsala) |
| French press, Turkish | Contain diterpenes / highest levels among unfiltered methods (Harvard, Wikipedia) |
| Boiled coffee | Highest per cup of all methods in the 2025 Uppsala study |
| Workplace brewing machines | Highest of the workplace machines tested; varied widely between machines and over time (Uppsala) |
Where metal filters fit
Wikipedia (citing Zhang et al., 2012) explains that paper-filtered coffee has negligible cafestol because the paper retains the diterpenes. AeroPress describes paper as absorbing oils and catching fines, while a metal disc “does not absorb oils or withhold fines”. Without that paper layer, a metal-filtered AeroPress or pour-over sits closer to French press than to paper-filtered drip. The sources above do not give a specific figure for metal-filtered AeroPress coffee, so no number is offered here.
The 2025 workplace-machine study
Researchers at Uppsala University, with analysis at Chalmers University of Technology, measured cafestol and kahweol in coffee from 14 workplace machines and compared it with other methods, publishing in Nutrition, Metabolism and Cardiovascular Diseases (2025). Their press release reports that a regular paper drip-filter maker removes almost all of both compounds, while many machine samples contained levels that could plausibly affect LDL cholesterol. Lead researcher David Iggman said that for people who drink a lot of coffee every day, “drip-filter coffee, or other well-filtered coffee, is preferable”. The release also notes that the latest Nordic nutrition recommendations advise reducing or avoiding boiled coffee, and that a controlled study with participants would be needed to pin down exact effects.
Median concentrations reported in the study abstract
| Coffee | Cafestol (mg/L) | Kahweol (mg/L) |
|---|---|---|
| Home-brewed, paper-filtered (n = 5) | 12 | 8 |
| Workplace liquid-model machines (n = 3) | 8 | 7 |
| Workplace brewing machines (n = 11) | 176 | 142 |
| Percolator / French press | ≈ 90 | ≈ 70 |
| Boiled coffee | 939 | 678 |
| Boiled, then poured through a fabric filter | 28 | 21 |
| Espresso (highest sample) | up to 2,447 | — |
Orrje E, Fristedt R, Rosqvist F, Landberg R, Iggman D. Nutr Metab Cardiovasc Dis 2025;35:103933. Concentrations are per litre; espresso is served in much smaller volumes.
Practical takeaways
- If you are watching LDL cholesterol, paper-filtered methods carry the least cafestol, according to every source above.
- A metal AeroPress disk, French press or unfiltered method lets more through. How much it matters depends on how many cups you drink.
- AeroPress users can switch filters freely — the same brewer works with paper or metal. See paper vs metal, explained.
- Talk to a doctor about your own cholesterol; this page does not replace medical advice.
Sources
- Cafestol — Wikipedia
- Harvard T.H. Chan School of Public Health — The Nutrition Source: Coffee
- Uppsala University — Cholesterol-elevating substances in coffee from machines at work (March 2025)
- Chalmers research database — Cafestol and kahweol concentrations in workplace machine coffee compared with conventional brewing methods
- AeroPress — Metal filter vs paper filters
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