Mediterranean diet and colorectal adenomas: a systematic review and meta-analysis of observational studies.

Colorectal adenomas (CRAs) are epithelial lesions of the large bowel that can develop into colorectal cancer. Some studies have shown an inverse association of the Mediterranean diet (MED) with adenoma, but the extent of the association is equivocal. Owing to the lack of meta-analytical evidence in the literature, we sought to assess the association between MED and CRAs by conducting a systematic review and meta-analysis. A comprehensive systematic literature search of observational studies was conducted via PubMed, Scopus, Google Scholar and Web of Sciences up to May 2023. Studies were included in our review if they evaluated the association between MED and CRA, following an observational study design. Six studies were included in this study. We found that adherence to MED was inversely associated with CRA risk (odds ratio, 0.79; confidence interval, 0.73-0.85); implying that higher adherence to MED could reduce the risk of CRA by ~21%. Stratification by the year of studies, sex, study design, country and exposure showed a significant association between MED and CRA. The results of the current study provide evidence of an inverse association between adherence to MED and CRAs.

A case-control study of Dietary Approaches to Stop Hypertension (DASH) diets, colorectal cancer and adenomas among Iranian population.

BACKGROUND AND AIMS: Colorectal cancer (CRC) is the third most common cancer, worldwide. Recently, much attention has been given to the association between Dietary Approaches to Stop Hypertension (DASH) and CRC, however, data on colorectal adenomas (CRAs) as its precursor are scarce. Thus, the purpose of this case-control study was to investigate the association of DASH score with the risk of CRC and CRA in Iranian adults. METHOD: A total of 499 participants, including 129 CRC and 130 CRA cases, along with 240 controls, were asked about their dietary intake via a validated questionnaire. The DASH score was then calculated based on a priori methods and categorized in quartiles. Multivariate logistic regression was performed to assess the association of DASH score and the risk of CRC and CRA. RESULTS: After adjusting for confounding variables, adherence to the DASH diet was associated with a reduction in the risk of CRC and CRA, respectively (OR of 4th versus 1st quartile = 0.04, 95% CI: 0.01-0.11, OR = 0.10, 95% CI: 0.04-0.22). Also, subgroup analysis based on gender showed that women and men with a higher DASH score had a significantly lower risk of CRC and CRAs. CONCLUSION: The results of this study demonstrated that adherence to a DASH dietary pattern could reduce the risk of CRC and CRA in men and women. Promoting a DASH eating plan can be helpful in reducing the risk of CRC.

Dietary nutrient patterns and the risk of colorectal cancer and colorectal adenomas: a case-control study.

Although the association between food patterns and the risk of colorectal cancer (CRC) and colorectal adenomas (CRA) has been explored previously, a distinct paucity of studies has evaluated the association of nutrient pattern and the risk of CRC and CRA as precursors of CRC. Thus, the purpose of this case-control study was to investigate nutrient patterns and their relationship with CRC and CRA in Iran. Two hundred forty hospital control, 129 newly diagnosed CRC and 130 newly diagnosed CRA patients were asked about their dietary intakes using validated questionnaires. To define the major nutrient patterns, principal component analysis was applied based on preselected nutrients, and four explainable nutrient patterns were obtained: Factor 1 (mixed), factor 2 (the antioxidant), factor 3 (dairy) and factor 4 (the high fat). Logistic regression was used to determine odds ratios (OR) with 95% confidence interval (CI) of CRC and CRA according to categories of nutrient patterns. After adjusting for confounders, factor 2 was significantly associated with lower risk for the CRC and CRA in the second category compared with the first, respectively (OR = 0.20, 95% CI: 0.12-0.34, OR = 0.34, 95% CI: 0.21-0.56). Participants in the highest category of factor 4 showed an increase in the risk of CRC and CRA, respectively, than those in the low category, in both crude and multivariate analysis (OR = 1.77, 95% CI: 1.57-2.95, OR = 1.85, 95% CI: 1.13-3.02). Among derived nutrient patterns, 'the antioxidant pattern' was inversely associated with CRC/CRA, whilst 'high fat pattern' showed a direct association with these diseases.

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, Ptrend = 0.001. ORQ3-Q1 for CAP = 0.48, 95% CI: 0.27-0.85, Ptrend = 0.01). The findings of this study suggested an inverse association between TAC and CRC and CAP risk.

Diet-dependent acid load and the risk of colorectal cancer and adenoma: a case-control study.

OBJECTIVES: Colorectal cancer (CRC) is the third and second most prevalent cancer in men and women, respectively. Various epidemiological studies indicated that dietary factors are implicated in the aetiology of CRC and its precursor, colorectal adenomas (CRA). Recently, much attention has been given to the role of acid-base balance in the development of chronic diseases including cancers. Therefore, the aim of the current study is to examine the association of diet-dependent acid load and the risk of CRC and CRA. DESIGN: In this case-control study, potential renal acid load (PRAL) was computed based on dietary intake of participants assessed via a validated FFQ. Negative PRAL values indicated a base-forming potential, while positive values of PRAL implied acid-forming potential of diet. Logistic regression was used to derive OR and 95 % CI after adjusting for confounders. SETTING: Tehran, Iran. PARTICIPANTS: A total of 499 participants aged 30-70 years were included in the study (240 hospital controls, 129 newly diagnosed CRC and 130 newly diagnosed CRA). The current study was conducted between December 2016 and September 2018. RESULTS: After adjusting for potential confounders, a higher PRAL was associated with increased odds of CRC and CRA. The highest v. the lowest tertile of PRAL for CRC and CRA was OR 4·82 (95 % CI 2·51-9·25) and OR 2·47 (95 % CI 1·38-4·42), respectively. CONCLUSIONS: The findings of the current study suggested that higher diet-dependent acid load is associated with higher risk of CRC and CRA.

The relationship between the index of nutritional quality and the risk of colorectal cancer and adenoma : a case-control study.

OBJECTIVE: Colorectal cancer is one of the most common cancers in the world, whereas dietary factors are its most modifiable risk factors. The index of nutritional quality is considered as a general overview of the nutrient content of diet. The aim of this study is to determine the relationship between the index of nutritional quality and the risk of colorectal cancer and adenomas. METHODS: Overall, 129 colorectal cancer and 130 colorectal adenoma cases and 240 healthy controls were studied in three major general hospitals in Tehran province, Iran. Index of nutritional quality scores were calculated based on information on the usual diet that was assessed by a valid and reliable Food Frequency Questionnaire. Multivariate logistic regression was used to estimate the relationship between the index of nutritional quality scores and the risk of colorectal cancer and adenoma. RESULTS: After controlling for several confounding factors, the index of nutritional quality of calcium, vitamin C, riboflavin, folate and fiber were associated with decreased risk of colorectal cancer [ORcalcium: 0.21 (0.08-0.52), ORvitC: 0.16 (0.09-0.28), ORvitB2: 0.35 (0.18-0.65), ORfolate: 0.33 (0.16-0.65), ORfiber: 0.35 (0.21-0.58)]. Also, the inverse association were observed between risk of CRA and the index of nutritional quality of calcium, vitamin C, riboflavin, folate and fiber [OR calcium: 0.32 (0.14-0.74), ORvitC: 0.51 (0.34-0.73), ORvitB2: 0.48 (0.28-0.82), OR folate: 0.44 (0.23-0.81), OR fiber: 0.62 (0.42-0.92)]. CONCLUSION: This study showed that individuals who have a healthier diet, high in calcium, vitamin C, riboflavin, folate and fiber and food groups like fruits, vegetables and whole-grain and less in sweets and red or process meats are at a lower risk of colorectal cancer and CRA than those with unhealthy and poor diet.

Healthy Eating Index-2010 and Mediterranean-Style Dietary Pattern Score and the risk of colorectal cancer and adenoma: a case-control study.

Background: Several studies have examined the relationship between diet quality indices and colorectal cancer (CRC). However, data on the association of these indices and colorectal adenomas (CRA) as a precursor of CRC are scarce. Our objective was to investigate the association of Healthy Eating Index (HEI-2010) and Mediterranean-Style Dietary Pattern Score (MSDPS) with CRC and CRA risk.Methods: This is a hospital-based case-control study including 259 cases (129 CRC and 130 CRA patients) and 240 controls with non-neoplastic conditions. Dietary intake of subjects was examined using a valid and reliable food frequency questionnaire. The HEI-2010 and MSDPS were then calculated based on a-priori methods. Multivariate logistic regression analyses were conducted to estimate the relationship between HEI-2010 and MSDPS and the risk of CRC and CRA.Results: After adjustment for confounders, compared with the first tertiles, the highest tertiles of HEI-2010 and MSDPS were significantly associated with lower odds of CRC (OR = 0.04; 95% CI = 0.01-0.12, OR = 0.19; 95% CI = 0.09-0.38, respectively). Similarly, the highest tertiles of HEI-2010 (OR = 0.04; 95% CI = 0.08-0.32) and MSDPS (OR = 0.19; 95% CI = 0.17-0.58) were associated with reduced odds of CRA compared to the lowest tertiles.Conclusion: The findings of this study suggested that a high-quality diet assessed by HEI-2010 and MSDPS is inversely associated with the risk of CRC and CRA.