Wikipedia URL:
http://en.wikipedia.org/wiki/Fish_oil
I have been supplementing with both fish and cod liver oil in either soft gel or liquid form for more than 10 years now. I have always sought out and taken pharmaceutical grade fish oil. I do this for two main reasons -
1) fish oil has documented benefits for the brain, heart and blood all which were damaged by my toxic chemotherapy in the form of V.A.D., cytoxan and periphal blood stem cell transplant.
2) fish oil has documented antiinflammatory properties. Inflammation, I believe, is one of the causes of cancer.