Cafestol is a substance found in coffee beans. Depending on how the beans are processed and brewed, it is present in varying levels in the coffee itself. The chemical is still being studied, but it has been shown to have a number of properties which are of concern to scientists and doctors. Both Arabica and Robusta beans have been demonstrated to contain the compound.
The substance is a diterpene molecule, meaning that it is in the terpene class of hydrocarbons. Terpenes tend to have strong scents, flavors, and essential oils, and residual cafestol is one of the substances which gives coffee a slightly oily, bitter flavor. It appears in Coffea arabica in concentrations of approximately .06% by weight. It is also present in Coffea robusta, which has a higher caffeine content than Arabica.
Robusta beans contain less of the substance than Arabica beans. In addition, they contain virtually no kahweol, another diterpene compound found in Arabica beans. The exact actions of kahweol on the body are unclear, as the compound is difficult to isolate for study.
International research has shown cafestol elevates cholesterol levels. It also elevates liver enzymes, which could potentially be harmful to a coffee consumer's health. Fortunately, there are ways to reduce the amount of the substance present in brewed coffee. When coffee is boiled, it has a much higher level. French press and traditional Turkish coffee both harbor much more cafestol than filtered coffee, which has negligible amounts of the compound.
Women appear to be more susceptible to the health problems associated with cafestol than men. The residual amounts of the compound in filtered coffee, for example, does have an impact on women, but not on men. Female coffee drinkers may want to consider drinking only filtered coffee, and perhaps cutting down on their consumption as well. If caffeine is an issue, increasing your intake of tea or switching to less flavorful but more powerful Robusta beans can meet your needs without exposing you to potentially harmful compounds in coffee.
Coffee is extremely complex, chemically. In addition to cafestol, there are numerous other compounds in coffee which have an impact on its flavor, smell, and potential health risks. Like many complex foods, not all of the compounds in coffee have been identified and fully studied, although researchers are working on it. Further research may reveal additional benefits to coffee which should be weighed when considering the potential health problems associated with cafestol.