The view prevailed in the 1950s to 70s that cancer was primarily caused by synthetic substances in the environment, especially in food. Even low concentrations of substances recognized as carcinogenic in high-dose feeding studies were to be avoided in foodstuffs. The no-threshold-concept of carcinogens became dogma. In the meantime, high-dose animal feeding studies have shown about half of all tested natural substances to be carcinogens. Due to improved analytical methods, ever more carcinogens were detected in food, such as lately acrylamide. Nowadays, the search for anticarcinogenic food constituents is more interesting in research than the screening for yet another carcinogen. Why do we not all die of cancer in our youth, although we are continually exposed to potentially carcinogenic compounds, predominantly of natural origin and largely produced in normal human metabolism? Very recently, threshold doses have been shown unequivocally to exist for genotoxic carcinogens.