Objectives: Caffeine asin (coffee, cola, and tea) is the most widely consumed beverages worldwide. The current study aims to evaluate the effects of caffeine in different concentrations on human cultured peripheral lymphocytes, in healthy individuals, using comet assay. The extent of DNA damage reflects a balance between oxidative stress (the presence of hydrogen peroxide H₂O₂ as a reactive oxygen species ROS), and DNA repair ability (the presence of anti-oxidant may be caffeine substances at known concentrations). This is an important method to prevent and avoid many cancerous diseases in an era of various pollutants.

Methods: Ten milliliters of venous blood samples were collected from 40 healthy young individuals, and lymphocyte cultures were set up after lymphocyte isolation with ficoll centrifugation. The mixture of lymphocytes culture media was incubated in the sterile incubator for 5 min after adding serial concentrations of caffeine (100, 500, 5000, 10000) µg/ml, as(group1,2,3,4 respectively) to 5% H₂O₂. The levels of oxidative DNA damage were expressed as comet tail length.

Results: At concentration 100 ug/ml, there was a significant elevation in the mean comet tail length level in cultured lymphocytes treated with hydrogen peroxide (106.96 µm) compared with the treated with All (mixture of caffeine, and H₂O₂), 6.670 µm.

Conclusion: We’ve concluded that a caffeine concentration of 100 µg/ml possesses the strongest anti-oxidant properties and causes much less DNA damage in lymphocytic culture when exposed to hydrogen peroxide.