Water, fiber, flavours, colours, natural carcinogens and anti-carcinogens, and pesticide residues are among the tens of thousands of non-nutritive components of our food supply. With one exception, anything we eat or drink that doesn't contribute energy, or calories, can be considered a non-nutritive component. The exception is alcohol, which contributes calories but no nutrients.

Many non-nutrient food components are easily identified, while others are just beginning to be found. In the latter group are hundreds or perhaps thousands of phytochemicals. These are naturally occurring substances in plants that can both help and harm us. Some phytochemicals may contribute to aberrations in cells that become cancerous, while others may serve to block cancer initiators or promoters in the body.