A comprehensive evaluation of epidemiological evidence on processed meat intake in relation to cancer, cardiovascular, metabolic diseases and all-cause mortality: an umbrella review

Objective This study aims to provide a comprehensive overview of existing systematic reviews and meta-analyses, systematically summarizing the current evidence on the topic and exploring the relationship between processed meat (PM) consumption and various health outcomes. Methods A systematic search was conducted in PubMed, Embase, and Web of Science databases for systematic reviews and meta-analyses examining the relationship between PM consumption and health outcomes from the inception of each database until May 2025. This is a descriptive umbrella review that summarizes existing systematic reviews and meta-analyses without conducting further quantitative re-analysis of summary estimates using random- or fixed-effects models or prediction intervals. A total of 34 articles and 54 meta-analyses were included in the review. Use the validated AMSTAR2 tool to assess the methodological quality of studies included in the meta-analysis, and use GRADE to assign the level of evidence quality. Results The key dose-response results reported below were selected based on their high public health relevance and stable effect estimates across the included meta-analyses. Consumption of PM was found to be associated with higher risks of various cancers, cardiovascular diseases, metabolic disorders, and all-cause mortality. Dose-response analysis revealed that an increase in PM consumption of 50 g/day was associated with a 72% higher risk of gastric cancer, 17% higher risk of colorectal cancer, 4% higher risk of prostate cancer, and an 8% higher risk of chronic obstructive pulmonary disease (COPD). All the above dose-response associations are based on low to very low certainty evidence as assessed by the GRADE system. Conclusion Most studies suggest that PM consumption is associated with diseases such as cancer, cardiovascular diseases, and metabolic disorders, but the certainty of evidence for most outcomes is rated as low or very low by the GRADE system. Based on the report from the International Agency for Research on Cancer (WHO-IARC) and the World Cancer Research Fund (WCRF), no level of PM intake can be confidently considered safe for the prevention of chronic diseases such as colorectal cancer. Future research should include more well-designed prospective studies and randomized controlled trials to further explore the associations between PM consumption and various health outcomes.