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Background: Few studies assess the link between plant-based diets and colorectal cancer (CRC) incidence. To our knowledge, no study has examined the association between pro-vegetarian dietary pattern (PDP) and CRC globally or among Iranians. Therefore, the objective of our matched case-control study was to evaluate the association between PDP and CRC in the Iranian population., Methods: The present research was a hospital-based case (n = 71)-control (n = 142) study conducted in the same hospitals in Tehran, Iran. This study used a reliable and valid semi-quantitative food frequency questionnaire to evaluate the participants' dietary intake. According to the residual method, the selected plant and animal foods have been adjusted in the total energy intake to calculate the PDP index. Odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for confounding variables were also expressed using logistic regression by SPSS software., Results: In the crude and adjusted models, we observed that the odds of CRC decreased significantly in the 3rd and last quartile of PDP compared to the 1st quartile (Q) (Crude model: Q 3 : OR = 0.36, 95% CI: 0.17 - 0.79, P-value = 0.011 and Q 4 : OR = 0.33, 95% CI: 0.14 - 0.79, P-value = 0.012 - Adjusted model: Q 3 : OR = 0.41, 95% CI: 0.18 - 0.94, P-value = 0.035 and Q 4 : OR = 0.35, 95% CI: 0.14 - 0.87, P-value = 0.025)., Conclusions: Based on the results of the present case-control study in the Iranian population, it was concluded that PDP, which involves consuming vegetables, fruits, cereals, dairy products, and low meat consumption, reduces the odds of CRC. In conclusion, adherence to PDP is associated with a decreased odds of CRC., (© 2023. The Author(s).)

Colorectal cancer (CRC) is the third most prevalent and the second fatal cancer in the world. Ultra-processed foods (UPFs) are suggested to be related to various non-communicable diseases including cancers. However, studies on the relationship between UPFs and CRC are scarce. The aim of this study was to determine the association between consumption of UPFs and CRC. In a case-control study conducted in four hospitals in Tehran, Iran, consumption of UPFs in 71 CRC patients and 142 controls (patients with non-neoplastic diseases) were compared. Using 125-item semi-quantitative food frequency questionnaire, dietary intakes were assessed. We used Multivariate logistic regression to estimate the association between UPFs intake and risk of CRC. Intake of nondairy beverages ( P  = 0.009), processed meat and fast food ( P  = 0.04) was significantly higher in those in the highest tertile of UPFs intake compared to the lowest tertile. In addition, intake of UPFs was associated with higher risk of CRC. The association remained constant after adjustment for BMI, income, smoking, type of job, educational level, and physical activity (OR, 3.32; 95% CI, 1.44-7.61; P  = 0.003). Results of this study indicate that the intake of UPFs is associated with increased odds of CRC.