Association between red and processed meat consumption and colorectal cancer risk: a comprehensive meta-analysis of prospective studies

Abstract

Increasing evidence suggests that red and processed meat consumption may elevate the risk of colorectal cancer (CRC), yet the magnitude and consistency of this association remain debated. This meta-analysis aims to quantify the relationship between red and processed meat intake and the risk of CRC, colon cancer, and rectal cancer using the most comprehensive set of prospective studies to date. We conducted a comprehensive search in PubMed, Web of Science, Cochrane Library, Embase, and Google Scholar databases from 1990 to November 2024, to identify relevant prospective studies examining red, processed, and total meat consumption in relation to colorectal, colon, and rectal cancer risk. Hazard ratios (HR) and 95% confidence intervals (CI) were extracted for each study and pooled using a random-effects model to account for variability among studies. Statistical evaluation was executed using the online platform MetaAnalysisOnline.com. A total of 60 prospective studies were included. Red meat consumption was associated with a significantly increased risk of colon cancer (HR = 1.22, 95% CI 1.15-1.30), colorectal cancer (HR = 1.15, 95% CI 1.10-1.21), and rectal cancer (HR = 1.22, 95% CI 1.07-1.39). Processed meat consumption showed similar associations with increased risk for colon cancer (HR = 1.13, 95% CI 1.07-1.20), colorectal cancer (HR = 1.21, 95% CI 1.14-1.28), and rectal cancer (HR = 1.17, 95% CI 1.05-1.30). Total meat consumption also correlated with an elevated risk of colon cancer (HR = 1.22, 95% CI 1.11-1.35), colorectal cancer (HR = 1.17, 95% CI 1.12-1.22), and rectal cancer (HR = 1.28, 95% CI 1.10-1.48). This meta-analysis provides robust evidence that high consumption of red and processed meats is significantly associated with an increased risk of colorectal, colon, and rectal cancers. These findings reinforce current dietary recommendations advocating for the limitation of red and processed meat intake as part of cancer prevention strategies.

Keywords: Aging; Colon cancer; Colorectal cancer; Diet; Dietary; Dietary recommendation; Healthy aging; Meta-analysis; Processed meat; Rectal cancer; Red meat; Risk factor; Semmelweis Study.

Fig. 1

Study selection process for the meta-analysis of prospective studies. After removing duplicates and title-based screening, 358 articles were retained. Following full-text review, 60 studies were included in the meta-analysis including (1) red meat studies, (2) processed meat studies, and (3) combined red and processed meat studies. Exclusions included non-relevant studies (n = 207) and full-text articles excluded for reasons such as non-longitudinal design (n = 14), failure to meet inclusion criteria (n = 33), lack of relevant data (n = 28), or other reasons (n = 16)

Fig. 2

Forest plot of the association between red meat consumption and the risk of colon, colorectal, and rectal cancer. Hazard ratios (HRs) with 95% confidence intervals (CIs) are shown for individual studies and pooled subgroups. Subgroup analyses are presented for colon cancer, colorectal cancer, and rectal cancer, with statistical heterogeneity assessed for each. Squares represent individual study HRs, with the size reflecting the study weight, and diamonds indicate pooled estimates. The overall HR indicates an increased risk of cancer associated with red meat consumption (HR = 1.18, 95% CI 1.13–1.23). The analysis demonstrates moderate heterogeneity across studies (I² = 29%; p = 0.01). Abbreviations: CI, confidence interval; HR, risk ratio; IV, inverse variance; SE, standard error

Fig. 3

Funnel plots illustrating the relationship between hazard ratios (HRs) and standard error (SE) for the association between red meat (A–C), processed meat (D–F), or total meat consumption (G–I) and the risk of various gastrointestinal cancer subtypes: colon cancer (A, D, G), colorectal cancer (B, E, H), and rectal cancer (C, F, I). The shape and symmetry of the funnel plots can offer insights into potential publication bias, with asymmetrical plots indicating the possibility of selective reporting or publication of the studies with certain outcomes

Fig. 4

Forest plot of the association between processed meat consumption and the risk of colon, colorectal, and rectal cancer. Each subgroup presents individual study results with hazard ratios (HRs) and 95% confidence intervals (CIs), using a random-effects model. The pooled estimates for colon, colorectal, and rectal cancer are shown, along with heterogeneity statistics. According to the overall HR presented at the bottom of the plot, processed meat consumption is associated with an increased risk of colon, colorectal, and rectal cancer (HR = 1.19, 95% CI 1.15–1.25). Moderate heterogeneity is observed among studies (I² = 33%; p = 0.01). Abbreviations: CI, confidence interval; HR, hazard ratio; IV, inverse variance; SE, standard error

Fig. 5

Forest plot illustrating the association between total meat consumption and cancer risk across different colorectal cancer subtypes. The diamond represents the pooled effect size for each subgroup and overall effect. The horizontal lines indicate the 95% confidence intervals (CI) for individual studies, with the size of squares proportional to study weight. The overall HR indicates an increased risk of cancer associated with total meat consumption (HR = 1.19, 95% CI 1.14–1.24). The analysis demonstrates moderate heterogeneity across studies (I² = 11%; p = 0.26). Abbreviations: CI, confidence interval; HR, hazard ratio; IV, inverse variance; SE, standard error