Could Fish Oil Interfere With Cancer Care?

Fish oil supplements, and even certain fish, may hinder the effectiveness of cancer-fighting chemotherapy, a new study suggests.

Dutch researchers found herring, mackerel and three other fish oils increased blood levels of the fatty acid called 16.4(n3) in cancer patients. Experiments in mice have suggested this fatty acid makes cancer cells resistant to chemotherapy, the researchers said. But, it’s not certain that what was found to happen in mice would happen with human cancer patients.

Experts noted that research on whether fish oil hurts or helps cancer patients has produced mixed results.
“Dietary supplements are not necessarily benign,” said Dwight Kloth, director of pharmacy at Fox Chase Cancer Center in Philadelphia, who had no role in the new study. “There are numerous cases in the literature where nutritional supplements and herbal drugs have had deleterious interactions with chemotherapy.”

Many patients begin taking supplements after they receive a cancer diagnosis, but concern is growing that supplements might interfere with anti-cancer treatments, according to background information with the study.

“Our research shows that when you affect the membrane of cancer cells by altering the fats in the outer covering of the cell, you can make the membrane stiffer or more fluid,” explained Christine Mets, director of the Laboratory of Medicinal Biochemistry at the Feinstein Institute for Medical Research in Manhasset, N.Y.

“These fats can make it more difficult for chemotherapy to enter the cell or make the cell better at pushing the chemotherapy out of the cell,” added Metz, who wasn’t involved in the study.

The study authors and other experts said the new report, published April 2 in the journal JAMA Oncology, doesn’t prove that fish oil blunts chemotherapy’s effects in humans.

“Taken together, our findings are in line with a growing awareness of the biological activity of various fatty acids and their receptors and raise concern about the simultaneous use of chemotherapy and fish oil,” the researchers wrote.

“Until further data become available, we advise patients to temporarily avoid fish oil from the day before chemotherapy until the day thereafter,” the researchers added.



Dr. Nagashree Seetharamu, an oncologist at North Shore-LIJ Cancer Institute in Lake Success, N.Y., said research on whether fish oil is harmful or beneficial for cancer patients has yielded conflicting results. “At this time, there is no strong evidence to support or refute the use of fish oil supplements during chemotherapy,” Seetharamu said.

My Take:
Omega 3 fatty acids are essential fatty acids. We can not manufacture them in the body, like omega 5, omega7, or omega 9s. They must be in the diet.

Without adequate omega 3 fatty acids, the body cannot make cell membranes. This is true for cancer cells as well as the healthy cells of our body.

The question to ask is whether a deficiency of omega 3 fatty acids helps or hurts the mortality rate when using chemotherapy. If you kill enough healthy cells, the patient will not survive the chemotherapy, even if you have killed the cancer.

Methyltrexate is a chemotherapy that works by interrupting folic acid metabolism. Folic acid is vital to cell reproduction. Researchers found that adding folic acid supplementation during chemotherapy with methyltrexate increased survival rates because the body was able to repair damaged tissues.

I suspect the same will be true with omega 3 fatty acids. It’s really a matter of when you supplement as well as what.

The Bottom Line:
Nutritional supplementation is vital before, during and after chemotherapy. However, you must work with a qualified nutritionist who is aware of the indications and contraindications of nutritional therapies.

Source: April 2, 2015 National Institutes of Health