The association of dietary insulin load and index with the risk of cancer and cancer mortality: a systematic review and meta-analysis.

Purpose: Insulin levels play an important role in cancer development. However, the link between an insulinogenic diet and cancer is still unclear. Therefore, we performed a systematic review with meta-analysis to investigate the association between dietary insulin index (II) and load (IL) with cancer risk and mortality.
Methods: A comprehensive search between electronic databases (Web of Science, PubMed/Medline, Scopus, and Google Scholar) was conducted to identify relevant studies up to January 2022. The relative risks (RR) and Odds ratios (OR) were extracted from eligible studies, and meta-analysis was performed to calculate the pooled effect size. Result: 12 papers including 14 studies (10 cohorts and 4 case-control) were included for the meta-analysis. Among them, 10 studies reported effect size for the risk of cancer, and 4 studies reported effect size for cancer mortality. We observed no significant association between II and IL with cancer overall (RRII: 1.03, 95%CI: 0.91-1.17, RRIL: 1.16, 95%CI: 0.94-1.42) and in cohort studies, however, in case-control studies was related with higher odds of cancer (ORII: 2.30, 95%CI: 1.21-4.38, ORIL: 2.57, 95%CI: 1.64-4.02). Higher II and IL scores were associated with the increased risk of total (RRII: 1.29, 95%CI: 1.02-1.63) and (RRIL: 1.39, 95%CI: 1.06-1.83) and colorectal cancer mortality (RRII: 1.29, 95%CI: 1.13-1.48) and (RRIL: 1.37, 95%CI: 1.18-1.60).
Conclusion: Higher dietary II and IL were not associated with cancer risk in overall and cohort studies, whereas related with a higher risk of cancer in case-control studies. We observed a significant positive relation of II and IL with cancer mortality, especially CRC mortality. Supplementary Information: The online version contains supplementary material available at 10.1007/s40200-022-01013-3. © Springer Nature Switzerland AG 2022.