Kahweol is a diterpene molecule found in the beans of Coffea arabica. Diterpenes are a type of hydrocarbon, and the presence of these molecules in coffee has been a subject of recent study and discussion. Unlike cafestol, another diterpene found in coffee, kahweol is somewhat difficult to isolate, chemically, and therefore studies on it have been difficult to perform. The two are actually chemically quite similar, but the difference may be important.
Coffea arabica is native to Ethiopia, and it is believed to be the superior variety of coffee, in terms of flavor. It has less caffeine than Coffea robusta, a less flavorful bean. Often, the two are blended together to produce a flavorful coffee which also has a high concentration of caffeine. The two beans have a number of important chemical differences which contribute to their respective caffeine levels and flavor, including the presence of cafestol and kahweol. Coffea arabica appears to have a higher concentration of cafestol in addition to kahweol, which may be a cause for concern.
Both cafestol and kahweol elevate cholesterol levels when they are consumed. The impact on cholesterol levels is a serious issue for people who already eat diets which are high in cholesterol. Kahweol, however, packs a double wallop, as it appears to elevate liver enzymes as well. Elevated enzymes indicate liver damage, and reflect a liver which is not performing as well as it should be. Studies on otherwise healthy volunteers have shown a link between the consumption of kahweol and liver enzyme levels.
However, kahweol may have a good side as well. Although no study has conclusively proved this, it is suspected that it may act as a blocker against some carcinogens, including aflatoxin B1, a toxin generated by fungus, and polycyclic aromatic hydrocarbons (PAHs), which are produced, like dioxins, when material is burned. Studies on this property of kahweol suggest that it may accomplish this by coordinating detoxifying enzymes in the body. More research, however, is needed.
Fortunately, there is an easy way to greatly reduce the amount of both of these hazardous substances. Filtering coffee causes both to decline to minimal concentrations in coffee, while boiled coffee and other unfiltered beverages retain the diterpenoids. For fans of French presses and Turkish coffee, this may not seem like such good news, but you may be able to find ways to reproduce the preferred flavor with the use of a filter, after some experimentation. The rich flavor of Turkish and French pressed coffee can be mimicked with filter coffee if you use a lot of freshly ground coffee beans with a filter.