Along with the other factors that cause abnormal cell growth, nutrition is the key to understanding of cancer occurring mechanisms and the effects of carcinogens on cell DNA.To activate toxins found in food, they need to be absorbed in our intestines, enter the blood stream and reach their destination cells. Toxins that cause cell damage and cancer cells growth can be naturally occurring in plants and animals that we use to feed ourselves, they can be found in environment or they can be formed during food heat processing. The most common naturally occurring carcinogens are enzyme inhibitors, glucosinolates in Brassica, histamine and aflatoxins. Toxins that get to our food from the soil and water that we use for food growth are dioxins, polycyclic aromatic hydrocarbones and heavy metals like mercury. Food processing and heating has been known to people since the start of their existance, and has been used to make foodmore digestable and safe to eat. Apart from the good, heat processing causes formation of carcinogenic compounds such as acrylamide, heterocyclic aromatic amines and nitrosamines. Special group of food carcinogens are food additives, which are intentionally added in food by human, and mustn't cause any health risk in a concentration that is legally prescribed. To avoid and protect ourselves from dangers that may be found in food, we must stay educated about proper food processing techniques, or completely avoid those types of food that are certain to contain carcinogens.