Fish Consumption and Colorectal Cancer Risk: Meta-Analysis of Prospective Epidemiological Studies and Review of Evidence from Animal Studies

SIMPLE SUMMARY: We meta-analyzed prospective epidemiological studies reporting on the association between fish consumption and colorectal cancer (CRC) risk among humans and reviewed preclinical studies that examined the link between fish components and colorectal carcinogenesis in animals. By pooling results from 25 studies (encompassing over 25,000 CRC cases) published up to November 2020, we found convincing evidence that increased fish consumption may protect from CRC development among humans. The review of animal studies allowed identifying several biological mechanisms able to explain the associations that have emerged in human populations. Dietary recommendations for cancer prevention should incorporate the evidence from this literature review and meta-analysis. ABSTRACT: Background: Epidemiological studies on the association between fish consumption and colorectal cancer (CRC) risk have yielded inconsistent results, despite evidence from preclinical studies that long-chain ω-3 polyunsaturated fatty acids inhibit colorectal carcinogenesis. We conducted a meta-analysis of prospective epidemiological studies investigating the association between fish consumption and CRC risk among humans and reviewed studies examining the link between fish components and colorectal carcinogenesis in animal models. Methods: We included studies published until November 2020. We calculated the summary risk ratio (SRR) and 95% confidence intervals (CI) through random effects meta-analysis models in order to summarize evidence from studies among humans. Results: Twenty-five prospective epidemiological studies encompassing 25,777 CRC cases were included. Individuals in the highest (vs. lowest) category of fish consumption had a significantly reduced risk of CRC (SRR 0.94, 95%CI 0.89–0.99). In dose–response meta-analysis, a 50-g increment in the daily consumption of fish was associated with a statistically significant 4% reduction in CRC risk (SRR 0.96, 95%CI 0.92–0.99). Preclinical studies (n = 25) identified multiple mechanisms of action of fish and fish components on colorectal carcinogenesis. Conclusions: Dietary recommendations for cancer prevention should take into account the evidence from epidemiological and preclinical studies that increasing fish consumption may be effective in preventing CRC.