Fish oil supplements (including distilled versions and cod liver oil) contain the long chain omega-3 fatty acids EPA and DHA but may also contain persistent organic pollutants such as PCB (see also here) and DDT, as well as toxic elements such as arsenic and mercury (see a mercury comparison between vaccines and tuna here). Dark fish (such as salmon) consumption may be particularly problematic.
Because of these high levels of pollutants in fish, mercury levels in hair samples and arsenic levels in blood samples can now be used as biomarkers that can estimate a person’s past fish consumption.
The good news is that we can get all the omega-3s we need from plants. However, the omega-3 fatty acid most commonly found in plant foods is the short chain omega 3 ALA (alpha-linolenic acid). The body can lengthen ALA into EPA and DHA, but it may not convert enough for optimal health. Therefore, an fish-free DHA and/or EPA supplement may be a good idea. These plant-based supplements may provide all the benefits without the contaminants.
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