I dont know the answer to that question .. its something IVe wondered about too ... Im actually going to start taking 3 EPO a day and do it for about 2 months .. then Ill stop for a few days and see if my symptoms come back like they did a week or so ago ... I think for me its some kind of fatty acid deficiency but I dont know why or what started it ... I take the fish oil and EPO together - and it works very well so far. Its the only thing that has worked for me to give me relief and my lips are supple/moisturized naturally.