INTRODUCTION TO FOOD TOXICOLOGY
Food is one of the most essential materials for the survival of living organisms, in addition to oxygen and water. Food toxicology deals with the substances found in food that, when consumed, may cause harm to the consumers. Therefore, 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. Among various subdisciplines of toxicology, food toxicology has received wider public attention in recent years. This has been driven by an increased awareness of the health effects of foods, foodborne illness, as well as the rapid availability of information to consumers, thanks to the world-wide-web.
Typically, a food contains hundreds of substances. Apart from the most obvious constituents, a majority of the substances in various foods have not been fully characterized. The assumption that food is safe to consume is based on the history of its consumption. In recent years, there has been increasing interest on the part of consumers regarding the “health-promoting” properties of various naturally occurring constituents of food, such as phytosterols from vegetable oils and isoflavones from soy. The addition of substances to foods that do not contain them naturally has raised questions about how they should be regulated. There is a debate whether the concept of nutrients should be expanded to include a growing number of food constituents that seemingly produce health benefits (Sansalone, 1999). Because federal dietary guidance applies to the total diet and there are no widely accepted standards to judge the “healthfulness” of individual foods, fortification of foods with new substances should require a thorough evaluation of safety at the intended level of intake for the general population (Mackey and Kotsonis, 2002).
NATURE AND COMPLEXITIES OF FOOD
Food is a very complex mixture of nutrient and non-nutrient substances, whether it is consumed uncooked (e.g., raw agricultural product) or in a cooked and highly processed ready-to-eat form (Tables 27-1 and 27-2). Many of the non-nutrient substances are necessary for the growth and survival of the plant (from which they are derived), and for the plant's adaptation to the environment. 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. Traditionally, the nutrients in food are classified as calorigenic macronutrients, such as carbohydrates, proteins, and fats, and the non-calorigenic micronutrients, such as vitamins and minerals.