Effect of Supplementation With Omega-3 Fatty Acid on Risk of Colorectal Polyps

MedicalResearch.com Interview with:

Dr. Song

Assistant Professor, Epidemiology
Harvard T.H. Chan School Of Public Health
Assistant Professor of Medicine
Clinical and Translational Epidemiology Unit
Massachusetts General Hospital

MedicalResearch.com: What is the background for this study?

Response: Increasing data indicate that high intake of omega-3 fatty acid may reduce the risk of colorectal cancer. Since effects of nutritional factors on risk of cancer, a slow-developing disease, typically emerge only after several years, it is useful to study the effect of preventive agents on cancer precursors such as colorectal polyps. Colorectal polyps are small growths on the lining of the colon or rectum. Most polyps are harmless, but some can become cancerous.

To test whether supplemental omega-3 fatty acids reduce the risk of developing colorectal polyps, Drs. Mingyang Song and Edward Giovannucci from the Harvard T.H. Chan School of Public Health and investigators at the Brigham and Women’s Hospital conducted an ancillary study within the VITamin D and OmegA-3 TriaL (VITAL). VITAL is a randomized, placebo-controlled trial of supplementation with vitamin D3 (at a dose of 2000 IU per day) and marine n-3 fatty acid (at a dose of 1 g per day as a fish-oil capsule containing 840 mg of marine n-3 fatty acid, including 460 mg of EPA and 380 mg of DHA) in the primary prevention of cardiovascular disease and cancer among 25,871 men aged ≥50 and women aged ≥55 in the United States. Study physicians reviewed pathology records of a subsample of participants who reported a diagnosis of colorectal polyps to confirm the diagnosis and extract detailed clinical information. 

MedicalResearch.com: What are the main findings?

Response: Omega-3 supplementation did not reduce the risk of developing colorectal polyps in the overall study sample. However, in subgroup analyses, supplementation was associated with a lower risk of the main type of colorectal polyps among those with low blood levels of omega-3 fatty acids at study entry and among African Americans 

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: The potential benefit of omega-3 fatty acid supplementation for reducing colorectal polyps in these groups requires confirmation in future studies.


Song M, Lee I, Manson JE, et al. Effect of Supplementation With Marine ω-3 Fatty Acid on Risk of Colorectal Adenomas and Serrated Polyps in the US General PopulationA Prespecified Ancillary Study of a Randomized Clinical TrialJAMA Oncol. Published online November 21, 2019. doi: https://doi.org/10.1001/jamaoncol.2019.4587


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Last Updated on November 26, 2019 by Marie Benz MD FAAD