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  • Food is an exceedingly complex mixture of nutrient and nonnutrient substances.

  • A substance listed as Generally Recognized as Safe (GRAS) achieves this determination on the adequacy of safety, as shown through scientific procedures or through experience based on common use.

  • An estimated daily intake (EDI) is based on two factors: the daily intake of the food in which the substance will be used and the concentration of the substance in that food.

  • Food hypersensitivity (allergy) refers to a reaction involving an immune-mediated response, including cutaneous reactions, systemic effects, and even anaphylaxis.

  • The vast majority of food-borne illnesses in developed countries are attributable to microbiologic contamination of food.


The practice of food toxicology involves detecting toxic substances in food, characterizing their properties, studying their fate in the body (absorption, distribution, metabolism, and excretion), and investigating their adverse health effects. Toxic substances can be naturally present in food, formed when the food is cooked, added directly to food, or they can find their way into food from the immediate environment, such as packaging. Typically, a food contains hundreds of substances. Apart from the most obvious constituents, most substances in foods have not been fully characterized. The assumption that food is safe is based on the history of its consumption.


Food is a complex mixture of nutrient and non-nutrient substances, whether it is consumed uncooked or in a cooked and/or highly processed ready-to-eat form. Many non-nutrient substances are necessary for the growth and survival of the plant (from which they are derived). Some of these substances may act as antinutrients rather than frank toxins, such as trypsin and chymotrypsin inhibitors, phytates that bind minerals, anti-thiamines in fish and plants, etc. Nutrients in food are classified as calorigenic macronutrients, such as carbohydrates, proteins, and fats, and the non-calorigenic micronutrients, such as vitamins and minerals.

The Food and Nutrition Board of the Institute of Medicine (IOM) developed Dietary Reference Intakes (DRIs) that serve as a guide for good nutrition. The DRIs provide a set of four nutrient-based reference values: Estimated Average Requirement (EAR), Recommended Dietary Allowances (RDA), Adequate Intake (AI), and Tolerable Upper Intake Level (UL).

The EAR is the average daily nutrient intake level estimated to meet the requirements of 50% of healthy individuals in a group, and the RDA is the daily dietary intake level sufficient to meet the nutrient requirements of nearly all healthy individuals in a group. The RDA is the EAR plus two standard deviations (RDA = EAR + 2SD). If sufficient information is not available to establish an EAR and calculate the RDA, an AI level is developed; AI represents the approximate estimates of nutrient intake by healthy people. The UL is the highest level of daily nutrient intake that is not likely to pose ...

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