by Jack Norris, RD

As promised in my March 6 post, Cancer Meta-Analysis, I conducted a literature review of long-chain omega-3s (EPA and DHA) and colorectal cancer. Here’s my summary:
Given the preponderance of null findings in well-powered individual cohorts, the inconsistency across studies, and effect sizes close to 1.00, a causal protective effect of fish intake on colorectal cancer risk remains uncertain, if not unlikely. This conclusion is reinforced by the evidence from randomized controlled trials (RCTs). Of the two largest trials, together enrolling over 40,000 adults, neither VITAL nor ASCEND found a significant effect of EPA+DHA supplementation on cancer incidence or mortality.
Given these findings, I don’t see a reason to recommend long-chain omega-3 supplements for vegans in order to prevent colorectal cancer. More details are in the article, Omega-3s and Colorectal Cancer.