Excerpts from: Cod Liver Oil — Notes on the Manufacture of Our Most Important Dietary Supplement, by David Wenzel.
Is Ultra-Clean (free-of mercury) Really Necessary?
. . . are either deodorization or molecular distillation necessary? The industry says yes. According to the owners of one mill I visited: “We have done some tests on non-deodorized CLO and have observed . . . dioxin-like PCB’s at a concentration of 6-8 picograms TE [WHO designation of Toxic Equivalent] per gram and some pesticides are also observed.”
However, during my studies, I talked to two fish oil scientists and one marine biologist who questioned the necessity for ultra-clean oils. They did not want to go on record but this is what they said in a nut shell:
“There have been metals, dioxins and PCBs in fish livers and our environment since the beginning of time. And while there may be a difference between man-made contaminants and naturally occurring contaminants, there are just as many or more contaminants in tomatoes and strawberries than in most fish oils. Left unsaid was the fact that vitamin A in cod liver oil protects against dioxins and pesticides (see page 32). Much of this protective nutrient is removed in the process of making the oil ultra-clean.
They also believed that concerns for mercury content in cod liver oil were misplaced, explaining that mercury has always been in the sea. The red color in plankton is methyl mercury. Plankton is the grass of the sea. Methyl mercury has always been part of man’s diet through the consumption of ocean fish. As one of my interviewees said: “One day we may find that some of the contaminants are actually nutrients.”