Plant-based diet and oxidative stress-induced DNA damage in post-surgery colorectal cancer patients: Results from a randomized controlled trial

Oxidative stress-induced DNA damage may impact long-term outcomes in colorectal cancer (CRC) patients. While bioactive compounds in plant foods have been linked to DNA protection, evidence among patients in remission remains limited. The present study aimed to investigate the effect of a one-year personalized intensive dietary intervention on DNA damage in post-surgery, non-metastatic CRC patients. Participants were enrolled 2-9 months after surgery in the ongoing randomized controlled trial, Norwegian dietary guidelines and colorectal cancer survival (CRC-NORDIET). Eligible participants (aged 50-80 years, primary stage I-III CRC) were randomized to either a plant-based dietary intervention targeting oxidative stress and inflammation, or to a control group that received standard dietary advice as a part of routine cancer care. As a secondary analysis, this study included 156 participants (78 in the intervention group and 78 in the control group) from the total 503 patients enrolled in CRC-NORDIET study. DNA damage in peripheral mononuclear blood cells (PBMCs) was assessed using the enzyme-modified comet assay during a 12-month follow-up period. A significant intervention effect on DNA base oxidation from baseline to 12 months was observed (P = 0.04), representing a 32 % reduction in the intervention group compared to the control group. No significant effect on DNA strand breaks was found. In conclusion, adherence to a plant-based dietary pattern may reduce DNA base oxidation in post-surgery CRC patients. Trial registration: ClinicalTrials.gov Identifier: NCT01570010.