A new study states that oil supplements, and even certain fish, may hinder the effectiveness of cancer-fighting chemotherapy.
The study, which was conducted by the researchers from the Netherlands Cancer Institute and published in the journal JAMA Oncology, states that cancer patients hoping to boost their recovery by taking supplements of fish oil could be doing themselves more harm than good. Consuming Omega-3 fatty acids, found in oily fish such as mackerel and herring, could stop chemotherapy drugs from working, according to the researchers.
Dr. Emile Voest, MD, PhD, Professor of Medical Oncology, Medical Director of the Netherlands Cancer Institute, and the lead author of the study, said, “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 .”
For their study, the researchers analyzed the rate of fish oil use among patients undergoing cancer treatment, while also recruiting healthy volunteers to examine blood levels of the fatty acid after ingestion of fish oils and fish. The researchers enrolled 118 cancer patients who responded to a survey about their diets. The researchers also looked at the levels of fatty acids in 50 healthy participants after they consumed either oily fish or fish oil supplements.
In the group of cancer patients, 35 said they regularly took fish oil supplements, and 13 said they used supplements with omega-3 fatty acids. The researchers found that the levels of fatty acid 16:4(n-3) increased in the participants after the recommended daily amount of 10 ml of fish oil was administered. Blood levels returned to normal eight hours after the dose, but took longer when the participants used 50 ml of fish oil.
The researchers also carried out a separate study on mice, which found that raised fatty acid levels prevented chemotherapy drugs from working properly.
“Based on our findings, and until further data become available, we advise patients to temporarily avoid fish oil from the day before chemotherapy until the day thereafter,” added Voest.