ABSTRACT
Our diet contains not only nutrients such as carbohydrates, fats, proteins, vitamins, and minerals, but also several nonnutrient substances, some of which have never been identižed. The number and variety of chemicals occurring naturally in foods are enormous. We are also exposed to a variety of chemicals, including food additives, drugs, insecticides, industrial chemicals, and pollutants collectively called xenobiotics (from Greek: xenos, foreign; bios, life). In addition, we produce our own toxins as normal breakdown products of tissue components; bilirubin, a product of heme, is an example. Despite the continual barrage of toxic materials that enter our body, we manage to remain viable because of a number of enzymes that oxidize, rearrange, and conjugate these toxins and thereby prepare them for rapid elimination.
