Yes, my understanding is that salmon oil can interfere with vitamin E absorption. A gal on FB was giving way too much oil which had this effect and it almost killed her Newf. IMHO I think we supplement way too much; basically killing our dogs with kindness. If a balanced diet is fed, the body will take what it needs... I don't feed raw because it's far easier to screw up the balance kibble affords. Again, MHO.