Dietary total antioxidant capacity and colorectal cancer and colorectal adenomatous polyps: a case-control study

Colorectal cancer (CRC) is the third most common and the third most deadly cancer worldwide. In Iran, CRC is the third and fifth most common cancer in females and males, respectively. Chronic oxidative stress has been implicated in the development of CRC and its precursor, colorectal adenomatous polyps (CAP). While there were a few studies that suggested a favorable role of individuals antioxidants on the CRC risk, the total antioxidant capacity (TAC) of diet has been less investigated. Consequently, the aim of this study is to investigate the association of TAC with the odds of CRC and CAP. This is a case-control study. The participants were 130 cases with incident, histologically confirmed CRC, 134 cases with incident of CAP and 243 hospital-based controls. TAC has been assessed with dietary ferric-reducing antioxidant potential and oxygen radical absorbance capacity method based on collected dietary intake data through a reproducible and valid food frequency questionnaire. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association between the TAC and CRC and CAP odds were estimated by multiple logistic regression. After controlling for potential confounders, TAC was significantly associated with CRC and CAP odds. (ORQ3-Q1 for CRC = 0.25, 95% CI: 0.13-0.46, P-trend = 0.001. ORQ3-Q1 for CAP = 0.48, 95% CI: 0.27-0.85, P-trend = 0.01). The findings of this study suggested an inverse association between TAC and CRC and CAP risk.