Omega-3 took a hit as a panacea of cancer prevention this summer. In the July 11 issue of the online Journal of the National Cancer Institute, a study by scientists at the Fred Hutchinson Cancer Research Center in Seattle showed the fatty acid accelerated prostate cancer.

Yet only a few weeks earlier, a study in the British Medical Journal reinforced the omega-3 benefit for women in preventing breast cancer. This study focused on consuming fish as the source of the fatty acid versus the supplements. It found that for each 0.1 gram or 0.1 percent energy increment of fish oils taken daily, the risk dropped by five percent.  

Researcher Emily White, from the same research center that released the prostate study, questioned the results of the breast cancer study on fish oil. In an article in bloomberg.com, she said, “There may be some factor associated with health consciousness with both eating high-omega 3 fish (e.g. salmon) and with reduced breast cancer risk, that was not controlled for in all studies,” White said. “Only a randomized trial can provide definitive evidence.”

The study on prostate cancer denouncing omega-3 created a significant problem in the medical community and created uproar in the food industry. “We now have one study telling you prostate cancer gets worse with omega-3, and another that tells you that in females, they actually have reduction of the cancer of the breast with the same thing,” says Luis F. Pineda, MD, an oncologist and trained chef in Birmingham. Pineda runs Cooking with Cancer, a nonprofit devoted to helping those with cancer eat better.

The recent prostate study, titled Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial, stated that men with high blood levels of the omega-3 fatty acids EPA, DPA and DHA had a 71 percent increased risk for high-grade prostate cancer, 44 percent increased risk for low-grade prostate cancer, and an overall 43 percent increase for all prostate cancers.

The authors don’t know why. But in breast cancer, Pineda says omega-3 purportedly inhibits inflammation. “It has a very, very similar action as aspirin does,” Pineda says. “Aspirin is an anti-inflammatory by blocking the prostaglandin.” Prostaglandin, along with prolactin, stimulates breast cells to produce cancer-causing radicals.

There is also strong support in medical literature for the idea that omega-3 helps with cardiovascular disease, says Pineda, putting men in a particular dilemma about the pros and cons of the fatty acid. “But the info that we have on omega-3 that benefits the heart is so good, don’t stop taking it,” he says. “But be cautious.”

But women should not doubt. With basically no side effects, women should continue to eat foods rich in fatty acids or take supplements. “The more you take, the better off you are,” Pineda says, recommending at least 500 milligrams a day and ideally 1000 milligrams. However, negative side effects have been found in people who take exceedingly high doses, around three grams a day.

The primary source for omega-3 is saltwater fish. Some varieties of freshwater trout also have relatively high levels. “Flax seed also has a significant amount,” Pineda says. “There is some question about what source is better. Some even say krill is better than fish oil because the chemical structure of the fatty acid differs in krill.”

Pineda prefers patients ingest omega-3 rich foods over taking supplements. “The more natural the product, the better,” he says.

No one currently doubts omega-3’s benefits in cardiovascular disease management. The American Heart Association recommends eating fish — particularly fatty fish such as mackerel, lake trout, herring, sardines, albacore tuna, and salmon — at least twice a week.

“Omega-3 helps with the cardiovascular structure by reducing triglycerides,” Pineda says. Triglycerides are part of the membrane of the cells, and omega-3 affects the permeability of the cell membrane. “It allows for certain beneficial elements of the environment to come in and out of cells easier and that may be the key to its beneficial qualities.” Fish oil also appears to help prevent and treat atherosclerosis by slowing the development of plaque and blood clots, which can clog arteries.

“Right now, people are questioning whether to advise males to take this supplement,” Pineda says. “My answer is, at this moment in time, don’t change anything you’re doing. The cardiovascular benefits are so significant, please continue what you’re doing at this time.”