The last couple of years there has been increase publicity of elevated mercury levels in fish. As a result patients are asking whether fish oil supplements are safe. I advise them to buy only fish oil that has the impurities distilled out. The manufacturer who go to the effort of distilling their oil will do this
Another question that I get asked is does taking fish oil increase your bleeding risks? Although fish oils have antiplatelet effects… so far this doesn’t seem to be clinically significant.
The omega-3s in flaxseed and some nuts are different than the ones in fish. They contain alpa-linolenic acid which is the precursor of EPA and DHA. But the amount of EPA and DHA the body converts from alpha-linolenic acid is minimal. Diets high in these foods might help decrease heart disease but not tryglycerides.