[Nutrition and health--toxic substances in food]

With respect to food, the most important factors causing adverse health effects are: an unbalanced diet, resulting in obesity or vitamin deficiencies, overconsumption of alcohol or fat, the presence of microbial contamination and the presence of natural toxins. Two additional factors, the presence of environmental contaminants and products formed on heating food, may also be of importance. It is generally assumed that, when combined, food-related factors contribute to around 35% of overall cancer incidence. The most important groups of health-threatening compounds to be found in the food chain include natural toxins, such as those produced by plants (phytotoxins), fungi (mycotoxins), marine algae (phycotoxins) and by bacteria, and toxins present in animals for human consumption, especially fish. A second important group of toxic compounds in food consists of environmental contaminants, including heavy metals and persistent organic pollutants, such as dioxins and polychlorinated biphenyls, all of which may unintentionally end up in the food chain. A third group of toxins present in food are those substances produced when food is heated, and include polycyclic aromatic hydrocarbons, heterocyclic amines and acrylamide.