Fish oil is a natural substance found in fatty fish, such as tuna, halibut, salmon, and sardines. Fish oil contains omega 3 fatty acids, which are generally considered healthy for you.
One article (1) discussed fish oil and addressed the issue of whether or not fish oil is dangerous to cancer patients. It cited an article published in JAMA that showed omega 3 fatty acids in supplements containing fish oil reduced the ability of chemotherapy agents to fight cancer in an animal model. It indicated that not all chemotherapy agents were affected by fish oil or by any other natural substance.
The study published in JAMA was not definitive and didn’t apply to all patients with cancer. It indicated that the research study was only a preliminary study and that patients should take fish oil supplements when they have cancer as long as they discuss this with their doctor.
Source: 1.Farber D. Should Cancer Patients Avoid Fish Oil? http://blog.dana-farber.org/insight/2015/04/should-cancer-patients-avoid-fish-oil/. Accessed 8/1/16.
Dr. Adem Gunes