Dietary Inflammatory Index and Odds of Colorectal Cancer and Colorectal Adenomatous Polyps in a Case-Control Study from Iran

Abstract

Background: Chronic inflammation is implicated in the development of colorectal cancer (CRC) and its precursor; colorectal adenomatous polyps (CAP). Some dietary factors are important triggers for systemic inflammation. Therefore, the present study aimed to investigate the association between the dietary inflammatory index (DII®) and the risk of CRC and CAP in an Iranian case-control study. Methods: 134 newly diagnosed CRC patients, 130 newly diagnosed CAP patients, and 240 hospitalized controls were recruited using convenience sampling. Energy-adjusted DII (E-DII) scores were computed based on dietary intake assessed using a reproducible and valid 148-item food frequency questionnaire. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CI) after adjusting for confounders. Results: The E-DII score ranged between −4.23 (the most anti-inflammatory score) to +3.89 (the most pro-inflammatory score). The multivariable-adjusted ORs for participants in the 3rd tertile compared to the 1st tertile was 5.08 (95%CI: 2.70–9.56; P-trend < 0.0001) for CRC and 2.33 (95% CI: 1.30–4.02; P-trend = 0.005) for CAP. Conclusions: Our findings suggest that more pro-inflammatory diets, indicated by higher E-DII scores, might increase the risk of both CRC and CAP. Future steps should include testing these associations in a prospective setting in Iran.

The Dietary Inflammatory Index Is Positively Associated with Colorectal Cancer Risk in a Chinese Case-Control Study

“…The present study provides evidence regarding the association between a higher E-DII score and an increased risk of colorectal cancer in a Chinese population. In concordance with this result, previous epidemiologic studies observed significant positive association between the DII and colorectal cancer risk [20][21][22][23][24][25][26][27][28][29][30][31][32][33]. A 2017 meta-analysis of four prospective cohort studies and five case-control studies also reported an overall 40% increased risk of colorectal cancer in the highest quartile of the DII score [44], a result consistent with what we found.…”

“…To date, five prospective cohort studies [20][21][22][23][24] and nine case-control studies [25][26][27][28][29][30][31][32][33] have investigated the association between the DII and colorectal cancer risk, and all of them have found that a higher DII score is associated with an increased risk of colorectal cancer. Four [30][31][32][33] of nine case-control studies were conducted in Asian countries, including South Korea, Jordan, and Iran. However, to the best of our knowledge, no study has been conducted in Chinese population, whose socio-demographic characteristics and dietary patterns that are characterized mainly by higher consumption of vegetables, rice and fish/sea food vary from those of other populations [34].…”

Dietary Inflammatory Index, Dietary Non-Enzymatic Antioxidant Capacity, and Colorectal and Breast Cancer Risk (MCC-Spain Study)

“…Thus, direct comparison to other E-DII/DII quantile categorizations is challenging: Most of the studies assessed the inflammatory potential of the diet using the DII (energy was included in the score or as a covariate in final models); depending on the study, the E-DII/DII score was estimated including different number of food/nutrient parameters; other approaches have been used to estimate E-DII besides the one published by Shivappa et al [44]; and only a few studies presented sex-specific E-DII/DII values. Despite these limitations, our E-DII range values in men are wider than the ones reported by the case-control study in Iran [73]. In women, our E-DII values are slightly lower than the ones reported by the case-control study in Germany; however, that study only included postmenopausal women [32].…”

Dietary Inflammatory Index and Non-Communicable Disease Risk: A Narrative Review

“…Therefore, it is not surprising that we have observed consistently strong positive relationships between the DII score and CRC. At this juncture, there are 13 papers published by our group on CRC incidence [42,78,79,80,81,82,83,84,85,86,87,88,89] from studies carried out in various populations across the world [81,82].…”