Health effects of unfiltered coffee : diterpenes in coffee and their effects on blood lipids and liver enzymes in man

R. Urgert

Research output: Thesisinternal PhD, WU


Boiled coffee raises blood levels of cholesterol and triglycerides in man. Cafestol and kahweol are responsible. These diterpenes also raise blood levels of alanine aminotransferase (ALT). The objective of the present studies was to further specify the health effects of cafestol and kahweol.

Unfiltered coffee contains up to 5 g of grounds per liter. Intake of 8 g/day of such grounds for 3 weeks raised cholesterol by 0.65 mmol/L and ALT by 18 U/L in healthy volunteers. Diterpenes in floating grounds thus contribute to the hyperlipidaemic and ALT- elevating effects of unfiltered coffee. Chemical analyses showed that boiled, cafeti6re (also called French press), and Turkish coffee are rich in diterpenes. Levels are moderate in espresso and mocha coffee, and negligible in percolated, instant, and filtered coffee.

We studied the separate activities of cafestol and kahweol in a randomised, double-blind cross-over study with 10 male volunteers. Intake of 63 mg/day of cafestol for 4 weeks raised cholesterol by 17%, triglycerides by 86%, and ALT by 78%. Additional intake of 51 mg/d of kahweol only marginally raised the lipid responses, but more than doubled the ALT responses. Cafestol therefore is more hyperlipidaemic than kahweol, but both affect liver cells.

To study long term effects, we gave 46 volunteers 0.9 liter/day of either filtered or cafetiere coffee for 6 months in a randomised experiment. ALT levels were still raised by 45%, and LDL by 9%, after 6 months of intake of cafetiere coffee, but most of the initial rise in triglycerides had disappeared.

Lipoprotein(a) is an atherogenic particle made by the liver. We found that lipoprotein(a) levels were 65% higher in chronic drinkers of boiled coffee than in peers drinking filtered coffee. However, supplements rich in diterpenes lowered lipoprotein(a) in four experiments.

In conclusion, the strong and persistent effects on total and LDL cholesterol levels are a good reason to advise patients with a high coronary risk to limit the intake of brews rich in cafestol. Effects of unfiltered coffee on triglycerides and lipoprotein(a) may be insignificant for atherogenic risk. The effects of cafestol and kahweol on liver cells may be innocuous, but coffee drinkers with raised levels of alanine aminotransferase might also do well in abstaining from unfiltered coffee.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Hautvast, J.G.A.J., Promotor
  • Katan, M.B., Promotor
Award date4 Apr 1997
Place of PublicationWageningen
Print ISBNs9789054856719
Publication statusPublished - 4 Apr 1997


  • coffee
  • food hygiene
  • nutritional state
  • consumption patterns
  • diterpenes


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