A friend of mine has a nasty allergic reaction to fish (nausea and some kind of tightening of the jaw apparently). I was trying to get them to find out from their doctor wheter or not it would be safe for them to take fish oil, but I'd say the chances of them raising the issue are somewhere close to zero. There seems to be a clear association along the lines of "fish=death" in their minds.
Would whatever component of fish that causes a reaction be present in a high-purity oil? Or are there any alternative EPA&DHA supplements on the market that aren't derived from marine animals?
Is anyone out there making grassfed-cow oil or anything?