The multifaceted mechanisms for coffee's anti-tumorigenic effect on liver.

Epidemiological studies have found an inverse association between coffee consumption and the risk of liver cancer. Animal data support such a chemopreventive effect of coffee. Substantial research has been devoted to the identification of coffee components that may be responsible for these beneficial effects. Based on the current available literature, three major components, i.e. coffee diterpenes cafestol and kahweol (C+K), caffeine and chlorogenic acid contribute to the beneficial effects. These components induce phase II detoxifying and antioxidant enzymes as well as inhibit the expression or decrease the activity of phase I activating enzymes thus prevent carcinogenesis. These components target different stages of a common pathway, Kelch-like ECH-associated protein 1 (Keap1)--NF-E2-related factor-2 (Nrf2)--antioxidant-responsive-element (ARE) signal pathway thus alter the ARE-dependent expression of genes needed in the anti-tumorigenic effects.