Whilst this article does not specifically refer to zinc deficiency and CFS, zinc deficiency affects DNA repair and immune function as well as increasing oxidative stress. PWC's appear to have lower levels of zinc than normal people. (Used up in repairing DNA and fighting oxidative stress?) http://www.ncbi.nlm.nih.gov/pubmed/16338007 Zinc has an antagonist, Cadmium, which reduces zinc levels and is not only found in cigarette smoke, car brake dust and other industrial applications but increasingly in the food chain and it can also act as an immune suppressant and disrupt thyroid function. http://www.healthy.net/scr/Article.asp?Id=2049&xcntr=1 I think the Zinc/cadmium ratio could have an important bearing on the extent of CFS symptoms, but I never hear much about it from those involved in treatment of PWC's.