Go Fish

Published on: 
CURE, Spring 2010, Volume 9, Issue 1

Omega-3s studied for cancer prevention

Omega-3 fatty acids have received a lot of interest in recent years. Numerous studies have confirmed their value in reducing cardiovascular events, relieving high blood pressure, and decreasing blood triglyceride levels, but can they also help prevent cancer? A growing body of research suggests the answer is yes.

“If cancer cells are present in the body, omega-3 fatty acids create an environment that is less conducive to cancer growth.”

It’s unlikely that omega-3s will be able to eliminate cancer cells completely, Hardman adds, but it’s conceivable that the fatty acids could slow cancer growth in leukemias and possibly other cancers to the point where it becomes a chronic condition that patients could live with rather than something acute.

Individuals looking to boost their intake of omega-3 fatty acids are encouraged to do so via food sources whenever possible. Fish oil supplements vary in amount of omega-3 fatty acids they contain—specifically DHA and EPA—and it’s not clear what the best ratio is for different uses. And although fish oil supplements have been found to be relatively safe, they can increase the risk of bleeding when taken with anticoagulants or anti-platelet agents, warns Lorenzo Cohen, PhD, director of the Integrative Medicine Program at M.D. Anderson. “In general, people should be strongly advised to consult their health care professional before taking any supplement,” Cohen notes.

While it may be years before researchers prove conclusively whether omega-3 fatty acids provide another effective weapon in the arsenal against cancer, many are excited by the possibilities. “Right now, the lesson is pretty clear as far as cardiovascular disease,” observes Demark-Wahnefried. “We don’t yet know the answer in cancer, but it looks very promising.”

Three types of fatty acids can be found under the omega-3 umbrella: alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. Our bodies don’t manufacture omega-3s, so we must obtain them from food sources or via supplements. Foods rich in omega-3s include flaxseed and cold-water fish such as salmon, herring, and tuna. Omega-3s are also found in certain types of nuts and legumes, including walnuts and soybeans.

Omega-3 fatty acids have anti-inflammatory properties, which is why they are associated with a lower risk of cardiovascular disease, arthritis, and related problems. However, researchers are only beginning to understand their role in cancer prevention.

“Omega-3 fatty acids are theorized to have a protective role in cancer because they tie into some important cancer pathways,” explains Wendy Demark-Wahnefried, PhD, RD, professor of behavioral science at M.D. Anderson Cancer Center in Houston. “If cancer cells are present in the body, omega-3 fatty acids create an environment that is less conducive to cancer growth. At the moment, however, no studies confirm that omega-3s prevent cancer cells from developing.”

According to Demark-Wahnefried and other researchers, omega-3 fatty acids appear to inhibit cancer growth in a wide variety of ways, such as by adversely affecting a cancer cell’s ability to divide; inducing apoptosis, or programmed cell death; cutting off a tumor’s blood supply; and stimulating killer-cell activity.

Such findings are derived from years of animal studies. By comparison, human studies have produced conflicting results. One of the more promising is a 12-patient pilot study on the effects of omega-3 fatty acids on early-stage chronic lymphocytic leukemia being conducted at Marshall University in Huntington, West Virginia. According to researcher Elaine Hardman, PhD, associate professor of biochemistry and microbiology, the long-term goal of the study is to see if omega-3 fatty acids given as supplements before chemotherapy can extend the length of time before patients require chemotherapy.

“Our patients are not taking chemo. However, in a drug sensitivity test, more cancer cells are killed with a much lower dose of chemo after patients have been taking the omega-3 supplement than before the same patient started the omega-3,” Hardman notes.