acute gastrointestinal illness resulting from the consumption of foods containing one or more representatives of three main groups of harmful agents: natural poisons (poison) present in certain plants and animals, chemical poisons, and microorganisms (mainly bacteria) and their toxic secretions.

The majority of cases of acute food poisoning are caused by bacteria such as Salmonella, Shigella, Escherichia coli, and staphylococcus and their toxic products (see botulism and salmonellosis).

Among the chemical poisons contaminating foods are certain heavy metals used in fungicides and insecticides (see mercury poisoning). Instances of metal poisoning may sometimes be traced to the serving or preparation of acidic foods in certain cookware (see antimony poisoning; cadmium poisoning). Various food additives and preservatives, though generally innocuous on a short-term basis, may exert a cumulative toxic effect when ingested over a long period.

The more common poisonous plants and animals that cause food poisoning in humans include certain varieties of mussels and clams (see shellfish poisoning); ocean and freshwater fish (see fish poisoning); fungi (see mushroom poisoning); plants (e.g., water hemlock, rhubarb greens); and nuts (e.g., akee nuts), seeds (e.g., tung seeds), and beans (e.g., fava beans).