Abstract
Coffee oil derived from spent coffee grounds of Coffea arabica is considered a novel food in the European Union (EU), requiring pre-market approval supported by comprehensive toxicological data. The effects of coffee oil on human health, particularly on blood parameters and liver enzymes, have been investigated in several studies. This review article summarizes the available toxicological literature on coffee oil, including its bioactive diterpenes cafestol and kahweol, which are known for their potential health effects. Considering the different modes of action of these two diterpenes, moderate consumption of coffee oil may be considered safe for healthy adults. Based on the changes in serum values in humans, this review provides initial estimations of LOAEL, NOAEL, and ADI for these diterpenes. The findings suggest that an intake of 225 mg of coffee oil per day might be considered safe assuming that coffee oil contains about 0.4% diterpenes. In summary, the assessment based on the published data indicates that (i) the consumption of coffee oil contained in any type of prepared coffee appears to be safe because the homeostasis of lipid levels in the blood is not significantly affected, and (ii) a low consumption of coffee oil as such might be acceptable but would require a refined risk assessment considering the exposure levels of the intended food product, which must be provided for novel food approval procedures.