Chlorophyll protects against cancer when tested against the relatively low levels of carcinogens usually found in our environment. However, at high concentrations it actually increases cancer growth! It is interesting how nature produces our food in that it has chemicals that are clearly carcinogenic in them, but also includes the antidote, chlorophyll. This was an argument that organic foods were not necessary, however, for me I don't need the extra carcinogen load in my food. So, eat your greens and you'll have just the right amount of cancer preventing chlorophyll.