Essential Fatty Acids (EFAs)
What is it? Overview Usage Side Effects and Warnings

What is Essential Fatty Acids (EFAs)?

EFAs and their sources are generally regarded as harmless, except when there might be a food allergy involved (such as an allergy to shellfish). One concern with fish and fish-oil supplements involves the accumulation of mercury, PCBs, and other environmental toxins. For information that can help you make safe fish choices, see the Environmental Working Group's "Fish List." For fish oil supplements, look for products that are certified to not contain high levels of environmental toxins.

Fish oil has a mild blood-thinning effect;2 in one case report, it increased the effect of the blood-thinning medication warfarin (Coumadin).3 Fish oil does not seem to cause bleeding problems when it is taken by itself4 or with aspirin.5 Nonetheless, people who are at risk of bleeding...