Plant-Associated Natural Food Toxins

Abstract

Plants and/or associated microorganisms produce an enormous variety of bioactive compounds some of which can elicit a wide range of adverse effects ranging from simple gastrointestinal upsets, lingering neurological disease through to death. The toxins can be endogenous to the food plant or an exogenous contaminant introduced from a co-harvested plant or by associated fungi or bacteria. More usually, in a balanced, healthy diet, the toxins are well below the threshold for acute and even chronic toxicity. Bulk marketing of many food plants and products has a diluting effect on any localized high concentrations of endogenous and exogenous toxins thereby reducing the risk of related food poisonings. However, many factors can unbalance a diet leading to an increase in the exposure to the potential toxins. Furthermore, under specific circumstances, the food plant can overproduce these toxins leading to localized outbreaks of poisoning. This chapter briefly details a wide range of endogenous toxins that have been identified in some food plants and briefly reviews some examples of detoxifying preparation of food, misidentification of food plants with similar but toxic plants, misuse of potentially toxic food plants, food plant-associated intoxications of uncertain etiology, and the potential for secondary poisoning that may occur following ingestion of food products derived from animals that ingested the toxic plants. Additionally, the potential for otherwise safe food plants to be contaminated with exogenous plant-associated toxins is exemplified by brief discussions of dehydropyrrolizidine alkaloids, corynetoxins, ptaquiloside, and phomopsins, four toxin groups quite different in structure and effects. The wide range of in vivo biochemical and physiological interactions potentially involving bioactive plant-associated metabolites, including interactions with therapeutic drugs, reinforces the imperative to continue identification of disease states that could be caused, initiated, or exacerbated by exposure to these toxins. Such exposure can range from short term and high levels through to the more insidious long-term, low-level exposures.