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Health benefits of dark coffee – protecting blood cells from DNA damage

 Good news coffee fans! A group of researchers from the University of Vienna, Austria have recently published their investigation into the protective properties of dark coffee consumption. After 8 weeks of coffee or water consumption, DNA strand breaks in blood lymphocytes of a group of healthy volunteers were significantly lower in the coffee-drinking group, compared to the water-drinking control group, suggesting the coffee blend had a DNA protective effect.


A single centred, controlled, randomized, parallel study design was used. After a “run-in” 4-week period, study participants consumed three large cups per day of a special dark roast coffee blend whilst the control group consumed the same volume of warm water. Blood samples were collected after the run-in period and on the last day of the 8-week intervention period.

The comet assay was performed upon collected whole blood samples to analyse spontaneous DNA strand breaks. 200 cells per slide were scored using Comet Assay IV, Instem.  The intensity of DNA in the comet tail was quantified and calculated as a percentage of overall DNA intensity in each respective cell.  Please see the original publication for full details.

This work builds upon many previous studies suggesting that coffee consumption is linked to potentially advantageous health effects and can protect DNA against oxidants and toxic compounds.  

The University of Vienna researchers studied the master regulator of oxidative stress transcription factor Nrf2 and its signalling pathway. A newly established fluorescence imaging method for Nrf2 translocation analysis in peripheral blood lymphocytes was used. Researchers conclude “a potential role of Nrf2 signalling in the response to coffee consumption cannot be ruled out entirely”.

The researchers highlight that;

  • Consumption of dark coffee protects blood cells from spontaneous DNA damage
  • Immunofluorescence imaging of PBLs facilitates quantitation of Nrf2 translocation
  • Activation of Nrf2 by coffee potentially not exclusively involved in DNA-protection

For full details please refer to the original publication “Dark coffee consumption protects human blood cells from spontaneous DNA damage“ 

Reference: Pahlke, Gudrun & Attakpah, Eva & Aichinger, Georg & Ahlberg, Katarina & Hochkogler, Christina & Schweiger, Kerstin & Schipp, Dorothea & Somoza, Veronika & Marko, Doris. (2019). Dark coffee consumption protects human blood cells from spontaneous DNA damage. Journal of Functional Foods. 55.

For our previous news story upon the protective properties of coffee please click here