Association of dietary carbohydrate intake, glycemic index, and glycemic load with colorectal cancer risk in adults: a systematic review and dose-response meta-analysis of prospective cohort studies

Carbohydrate consumption is a key factor in controlling insulin secretion; however, the effects vary by the glycemic index (GI) and glycemic load (GL), which might be associated with the risk of colorectal cancer. Due to conflicting results regarding their impact on colorectal cancer and considering that previous meta-analyses lacked dose-response analyses for colon and rectal cancer, this comprehensive dose-response meta-analysis was undertaken to explore the association between dietary carbohydrates, GI, and GL with the risks of colorectal, colon, and rectal cancers. A comprehensive search of online databases (PubMed, Scopus, Web of Sciences) up to November 2024 identified 23 studies with 2,019,665 participants. Random-effect models were used to calculate pooled effect sizes, and dose-response analyses assessed linear and nonlinear associations. We used the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) form. The results of this study revealed a marginal increase in colorectal cancer risk associated with a higher GI (RR: 1.08, 95% CI: 1.00 − 1.16, P = 0.04). However, in subgroup analyses, higher GI was significantly associated with an increased risk of colorectal cancer among men, in cohorts with follow-up durations shorter than 10 years, and in studies conducted in US populations. On the other hand, subgroup analyses indicated an inverse significant association between carbohydrate intake and colorectal cancer in specific subgroups, including men, women, studies conducted in non-US populations, and cohorts with follow-up durations shorter than 10 years. Furthermore, neither linear nor nonlinear dose-response analyses indicated a significant association between exposures and outcomes. These results suggest that a higher GI may be associated with an increased risk of colorectal cancer. Nevertheless, additional studies are required to establish a more definitive connection between carbohydrate intake and colorectal cancer risk.