NATURAL SOURCES OF TOXICANTS IN FOODS
All chemicals, whether synthetic or naturally occurring, exhibit toxicity at some level of exposure. Even drinking excessive amounts of pure water can kill through the induction of an electrolyte imbalance. Also, there is a condition called “water toxicity” that is due to decreased renal capacity to excrete water. In foods that are normal constituents of our diets, some natural chemicals can be present in doses that are sufficient to produce harmful effects. These chemicals may cause toxic reactions when eaten in normal amounts by a person who tends to misuse a certain food or consume it in large amounts. An example of this kind of a situation is consuming a food that is rich in protease inhibitors without the application of necessary cooking procedures. An abnormal food constituent eaten in normal amounts may also cause toxic reactions. An example of this situation occurs in honey, when the bee collects nectar from plants containing poisonous (even carcinogenic) alkaloids, and acetylandromedel or andromedol is transferred to the honey. A normal constituent of a food such as lactose in milk may be toxic (lactose intolerance) to an individual whose body lacks the enzyme lactase. Nitrates that are found in spinach and other green leafy vegetables can also cause toxic reactions by combining with the amines in the food’s structure to form carcinogenic nitrosamines. Table 6.1 summarizes the adverse reactions that can occur through the consumption of natural foods.