How Does Diet Influence GI Cancer Outcomes?

Although high consumption of fruits, vegetables, and fiber is linked to lower GI cancer risk and red and processed meats, alcohol, and sugary beverages are linked to higher risk, most existing research has examined these components in isolation. | Image credit: Rodica Ciorba - stock.adobe.com

Healthy dietary patterns, especially those rich in fruits, vegetables, whole grains, legumes, and dairy, are associated with reduced risk and mortality of gastrointestinal (GI) cancers, while unhealthy patterns high in red and processed meats, alcohol, and sugary beverages increase risk, according to data from a review.

Researchers of the systematic review and meta-analysis, published in Nutrition Reviews, sought to determine how dietary patterns influence GI cancer risk and GI cancer-caused mortality.

GI cancers—which refers to cancers that occur in the esophagus, stomach, liver, gallbladder, biliary tract, pancreas, small and large intestine, rectum, and anus— account for about 26% of global cancer cases and 25% of cancer-related deaths.2,3 Colorectal cancer (CRC) is the most common, followed by stomach cancer, liver cancer, esophageal cancer, and pancreatic cancer.4

Understanding the impact of diet on GI cancer risk requires looking beyond individual foods or nutrients to consider overall dietary patterns.1 Although high consumption of fruits, vegetables, and fiber is linked to lower GI cancer risk and red and processed meats, alcohol, and sugary beverages are linked to higher risk, most existing research has examined these components in isolation.

The authors argued that this approach overlooks the way people actually eat, with complex interactions between various foods and nutrients. Data-driven methods like principal component analysis (PCA) and reduced rank regression (RRR) can capture these broader dietary patterns, but studies using these methods have produced inconsistent results. Some evidence suggests that RRR-derived patterns may show stronger associations with health outcomes, including cancer, than PCA-derived patterns. However, the extent to which these methods differ in capturing the relationship between diet and GI cancer risk and mortality remains unclear.

The researchers followed PRISMA 2020 guidelines and included cohort studies assessing the link between dietary patterns and GI cancer risk or mortality. Only studies using a posteriori or hybrid methods with relative risk (RR) or hazard ratio (HR) data were included.

Databases were searched through June 2023. Reviewers independently screened studies, extracted data, and assessed quality using the Newcastle-Ottawa Scale. Dietary patterns were labeled “healthy” or “unhealthy” based on food components and 2018 World Cancer Research Fund/American Institute for Cancer Research cancer prevention guidelines.

Out of 2,259 articles identified, 28 studies conducted between 2001 and 2023 were included, encompassing 1.7 million participants across 17 countries. The majority of studies used PCA to derive dietary patterns, with a focus on CRC as the primary endpoint, along with liver, stomach, esophageal, and pancreatic cancers.

Healthy dietary patterns, characterized by high intake of vegetables, legumes, and fruits, were associated with a significant protective effect in 6 of 42 studies. Adherence to a healthy diet was linked to a 10% reduced risk of CRC (RR, 0.90; 95% CI, 0.82-0.98) and a 9% reduced risk of GI cancer in men (RR, 0.91; 95% CI, 0.83-0.99).

Conversely, unhealthy dietary patterns, marked by high consumption of processed meats, refined grains, and desserts, were associated with a significant increased risk of cancer in 5 of 29 studies. These diets were linked to a 14% increased risk of CRC (RR, 1.14; 95% CI, 1.05-1.24) and a 23% increased risk of liver cancer (RR, 1.23; 95% CI, 1.03-1.45). In women, unhealthy diets were associated with a 25% increased overall GI cancer risk (RR, 1.25; 95% CI, 1.13-1.38).

Regarding mortality, healthy dietary patterns were linked to a reduced risk of death from CRC and esophageal cancer, while one study found that unhealthy dietary patterns increased the risk of colon cancer mortality (HR, 2.32; 95% CI, 1.36-3.96). Subgroup analyses showed no significant differences based on sex or cancer type, and low heterogeneity was observed across most analyses.

Although the review highlighted the benefits of PCA-derived healthy diets, limitations were noted, such as the subjectivity in defining dietary patterns based on food factor loadings, potential selection bias due to language restrictions in the study search, and insufficient data for subgroup analysis. Despite this, PCA-derived dietary patterns were more strongly associated with GI cancer risk than those derived by RRR. The highest intake of PCA-derived healthy foods reduced GI cancer risk by 10%, whereas the highest intake of unhealthy foods increased risk by 11%.

Moreover, the study suggests that certain foods, particularly fruits, vegetables, whole grains, and legumes, may improve survival following a GI cancer diagnosis due to their cancer-protective properties, anti-inflammatory effects, and ability to reduce oxidative stress. On the other hand, processed meats, red meats, and sugary foods were associated with increased cancer mortality.

The analysis also emphasized that dietary patterns might influence GI cancer risk through various biological mechanisms, such as improved gut health, reduced inflammation, and better regulation of glucose and insulin. The authors concluded by saying that further prospective research is needed, especially studies focusing on specific cancer biomarkers and changes in dietary intake after cancer diagnosis.

References

1. Abebe Z, Wassie MM, Mekonnen TC, Reynolds AC, Melaku YA. Difference in gastrointestinal cancer risk and mortality by dietary pattern analysis: a systematic review and meta-analysis. Nutr Rev. 2025;83(3):e991-e1013. doi:10.1093/nutrit/nuae090

2. Lu L, Mullins CS, Schafmayer C, Zeißig S, Linnebacher M.A global assessment of recent trends in gastrointestinal cancer and lifestyle-associated risk factors. Cancer Commun (Lond). 2021;41(11):1137-1151. doi:10.1002/cac2.12220

3. Arnold M, Abnet CC, NealeRE, et al. Global burden of 5 major types of gastrointestinal cancer. Gastroenterology. 2020;159(1):335-349.e15. 10.1053/j.gastro.2020.02.068

4. Ferlay JEM, LamF, Colombet M, Mery L, Piñeros M, et al. Global Cancer Observatory: Cancer Today. International Agency for Research on Cancer. 2020. Accessed April 15, 2025. https://gco.iarc.fr/today