Years of research by a haemorheologist, Dr. Leslie O. Simpson, has demonstated shape changes in the red blood cell populations of people with a number of chronic disorders, including CFS/ME. Normally shaped red blood cells are biconcave discocytes, and are highly deformable, enabling them to deliver oxygen to all the body systems dependent on the tiny capillaries. This includes working muscles, the brain, and the endocrine system, all of which are dysfunctional in CFS/ME. Immediately fixed blood samples from people with CFS/ME show a majority of irregularly shaped red blood cells, which are rigid, therefore unable to pass into the capillaries (whose diameter is much smaller than that of the red blood cells.). EPO contains a precursor to a chemical which improves the flexibility (deformability) of the red blood cells, and a minimum dose of 4 g per day of EPO has been found to improve the quality of life of people with this condition. 6 g per day of fish oil also can be effective, as can injections of vitamin B 12 as copobalamin. Google Dr. L.O. Simpson, ME/CFS to find references to his many research papers.