For a number of reasons, whey protein can be a major factor in promoting intestinal toxemia. Whey contains no fiber , which is necessary to keep things moving consistently through the intestinal tract. Because it is highly processed, whey protein contains no live enzymes to break down the large whey proteins. The human body actually has a hard time breaking down the three primary proteins in whey. Taken together, these problems provide an optimum environment for non-beneficial intestinal bacteria to thrive in. In addition, whey is very acid forming, which lowers the pH of the normally alkaline environment of the intestinal tract, thus favoring the growth of unfriendly bacteria over beneficial bacteria.
Heavy consumption of the essential amino acid lysine (as indicated in the treatment of cold sores) has allegedly shown false positives in some and was cited by American shotputter C. J. Hunter as the reason for his positive test, though in 2004 he admitted to a federal grand jury that he had injected nandrolone.  A possible cause of incorrect urine test results is the presence of metabolites from other AAS, though modern urinalysis can usually determine the exact AAS used by analyzing the ratio of the two remaining nandrolone metabolites. As a result of the numerous overturned verdicts, the testing procedure was reviewed by UK Sport . On October 5, 2007, three-time Olympic gold medalist for track and field Marion Jones admitted to use of the drug, and was sentenced to six months in jail for lying to a federal grand jury in 2000.