Numerous epidemiological studies (for citations and review, see Ames, 2001; Halliwell 2001), have pointed at a close correlation between vitamin C intake on one side and arteriosclerosis and cancer incidence on the other side. Clearly vitamin C is important for humans: we cannot synthesize it; deficient intake results in scurvy; there are efficient carrier proteins for its uptake (Levine, 1999); it is a necessary cofactor for several enzymes and metabolic roles (Halliwell, 2001); and it is the most important water soluble reductant. It is present in high levels in sperm fluid (see section 11.4) and may also be important as an inhibitor of nitrosamine formation in the stomach (Mirvish et al., 1998).