Adulterated food is food that is generally, impure, unsafe, or unwholesome. The main federal laws governing adulterated foods are the Federal Food, Drug, and Cosmetic Act, the Federal Meat Inspection Act, and the Poultry Products Inspection Act. These laws contain separate language defining in very specific terms how the term "adulterated" will be applied to the foods each of these laws regulates. Products that are adulterated under these laws’ definitions cannot enter into commerce for human food use. Under U.S. law, using an ingredient not approved by the Food and Drug Administration (FDA) is one form of food adulteration. State statutes may also regulate adulterated food produced or sold in the state. The selling of adulterated food is subject to civil penalties.

The following is an example of a state statute defining adulterated food:
"(a) Food is adulterated if

1. it bears or contains a poisonous or deleterious substance which may render it injurious to health; but in case the substance is not an added substance the food is not considered adulterated under this paragraph if the quantity of the substance does not ordinarily render it injurious to health;
2. it bears or contains added poisonous or added deleterious substance which is unsafe within the meaning of ...
3. it consists in whole or in part of a diseased, contaminated, filthy, putrid, or decomposed substance, or if it is otherwise unfit for food;
4. it has been produced, prepared, packed, or held under unsanitary conditions in which it may have become contaminated with filth, or in which it may have been rendered diseased, unwholesome, or injurious to health;
5. it is, in whole or in part, the product of a diseased animal or an animal which has died otherwise than by slaughter, or that has been fed upon the uncooked offal from a slaughterhouse;
6. its container is composed, in whole or in part, of a poisonous or deleterious substance which may render the contents injurious to health.

(b) Food is adulterated if

1. a valuable constituent has been omitted or abstracted in whole or part;
2. a substance has been substituted in whole or part for a valuable constituent;
3. damage or inferiority has been concealed;
4. a substance has been added or mixed or packed with it to increase its bulk or weight, or reduce its quality or strength, or make it appear better or of greater value than it is.

(c) Confectionery is adulterated if it bears or contains an alcohol or nonnutritive article or substance except harmless coloring, harmless flavoring, harmless resinous glaze not in excess of four-tenths of one per cent, harmless natural wax not in excess of four-tenths of one per cent, harmless natural gum, and pectin. This subsection does not apply to confectionery containing less than one-half of one per cent by volume of alcohol derived solely from the use of flavoring extracts, or to chewing gum containing harmless nonnutritive masticatory substances.

(d) Food is adulterated if it bears or contains a coal tar color other than one from a batch which has been certified under authority of the federal act."