Higher Long-Chain Omega-3s Linked to Lower Risk of Colorectal Polyps in Women
[frame src="/wp-content/uploads/images/FOL4.12_Photo12.1.png" alt="" width="216" height="262" align="left"]The most effective preventive strategy for colorectal cancer, which is the third most common cancer in the U.S., is finding and removing its earliest abnormalities. These appear as polyps or small sacs in the colon or rectum (Illustration) and are detected during a colonoscopy exam. They are considered precancerous. Because colorectal cancer usually does not reveal itself until the disease is advanced, looking for its earliest warning signs offers the greatest protection. A recent study reported that adults 50 years of age or older who had had a colonoscopy in the preceding 10 years had a 77% lower risk of developing colon cancer. Those findings say clearly that early screening works. Several aspects of diet and particularly fish consumption have been linked to the development of colorectal cancer for years, but the data have been inconsistent. Although several studies have suggested that individuals with high intakes of fish or the long-chain omega-3 fatty acids (omega-3s) they contain have a lower risk of the disease, there are enough studies reporting no association or even a higher risk of the condition, so that the evidence remains inconclusive. [frame src="/wp-content/uploads/images/FOL4.12_Callout22.png" alt="" width="170" height="189" align="right"]Now, a fresh approach to this question has appeared. Investigators at Vanderbilt University, U.S., focused on whether the consumption of omega-3s was linked to the odds of developing colorectal polyps. One study suggested that supplementation with EPA, one of the two main omega-3s in seafood, was associated with the development of about 20% fewer polyps in patients with a genetically higher risk of developing these abnormalities. The Vanderbilt scientists studied the results of colonoscopies in adults who underwent routine screening. Participants with inflammatory bowel disease, cancer or a family history of colorectal cancer were excluded. The researchers collected information about the participants’ medical history, diet and socioeconomic factors. The most striking observation was that women with the highest intakes of omega-3s had a 33% lower risk of developing polyps compared with women in the lowest intake category. These women also had the lowest excretion of a substance linked to the development of colorectal cancer. The investigators suggested that the omega-3s were suppressing the production of this cancer-linked substance in the colon. Other evidence supports this interpretation. [frame src="/wp-content/uploads/images/FOL4.12_Callout23.png" alt="" width="188" height="206" align="left"]In men, high intakes of omega-3s were not associated with a lower frequency of polyps. However, men with the highest consumption of alpha-linolenic acid, the plant-based omega-3, were 50% more likely to develop polyps compared with men having the lowest intakes. There is no good explanation for this observation. Alpha-linolenic acid has been associated with the development of other cancers in some, but not all studies, indicating that these data are inconclusive. The most encouraging aspect of this study is the implication that higher intakes of omega-3s in women may substantially reduce the chance of developing the precancerous lesions that could progress to colorectal cancer. The study needs additional confirmation by others, but the important health consequences of these observations might hasten such research. We have too few interventions that might reduce the risk of colorectal cancer, so each one warrants careful investigation. Exploring why the response occurred only in women, not men, is another priority. The questions always seem to outnumber the answers.