Dark coffee consumption protects human blood cells from spontaneous DNA damage

Coffee increasingly attracts notice with respect to beneficial health effects. Our objective was to investigate DNA protective effects of a special roast coffee blend of pure Arabica (Coffea arabica L.) in healthy volunteers (n = 96), following a prospective, randomized, controlled study with parallel design (coffee versus water). Potential modulation of Nrf2 signaling was evaluated by focusing on its two master regulators, Nrf2 and Keap1, as well as on Nrf2 translocation in the volunteers' lymphocytes (PBLs). In this context a newly established fluorescence imaging method for Nrf2 translocation analysis in PBLs turned out as feasible and eligible tool applicable for future studies. After chronical coffee consumption (8 weeks) spontaneous DNA strand breaks were significantly lower in the coffee group compared to water control, suggesting a protective effect of the coffee blend. Nrf2 signaling was remotely affected, indicating that additional mechanisms of protection from DNA damage need to be considered.