Does eating processed meat such as sausage and ham cause colorectal cancer?
Regularly eating processed meat such as sausage and ham measurably increases your risk of colorectal cancer. Reducing your intake is one of the best-supported dietary recommendations for colorectal cancer prevention.
Processed meat such as sausage, ham, salami and bacon increases your risk of colorectal cancer. This finding is consistent across several large meta-analyses. People who eat a lot of processed meat compared with those who eat little have, on average, an 18 to 21% higher chance of developing colorectal cancer. For every additional 50 grams per day, that risk rises by approximately 18%. This is one of the most robustly supported associations in nutritional research.1,2,3,4
The association is clearest for colon cancer, with elevated risks of 13 to 21% across multiple independent analyses. For rectal cancer specifically, the picture is slightly less consistent: most recent studies also find an elevated risk of 17 to 22% there, but an older meta-analysis found no statistically significant association for rectal cancer in isolation.2,1,3
These are observational studies, not experiments. They show a statistical association, not proven causality. People who eat a lot of processed meat may also live differently in other ways. Researchers correct for many of those factors, but you can never rule that out entirely. Nevertheless, the WHO places processed meat in the highest risk category for carcinogens, meaning there is enough evidence to consider a causal relationship likely.
There is also a biological explanation. Gut bacteria convert proteins and fats from meat into substances that promote inflammation and can damage intestinal cells. Dietary fibre normally drives the production of butyrate, a substance that protects intestinal cells. A low-fibre, high-meat diet disrupts that balance and reduces that protective effect.5,6
Processed meat does not stand alone either. A study of more than 142,000 people found that high consumption of ultra-processed food in general is associated with an 18 to 20% higher chance of developing colorectal polyps, the precursors of colorectal cancer. That association persisted even when processed meat was removed from the calculation.7 Estimates from population research suggest that approximately half of the colorectal cancer risk can be influenced through lifestyle, including diet.8,6,5
Based on several large meta-analyses of prospective studies (tens to hundreds of studies per meta-analysis), supplemented by mechanistic research into gut bacteria and one large cohort study on ultra-processed food and colorectal polyps. The associations are consistent, but the evidence for causality is largely observational in nature.