The dilemma of “good” and “bad” glucosinolates and the potential to regulate their content

Glucosinolates (GSLs) are a group of sulfur- and nitrogen-containing glycosides found in abundance in Cruciferous plants, including many important vegetable species of the Brassica genus such as broccoli, cabbage, and cauliflower. They are considered as highly bioactive secondary metabolites with significant effects against various types of cancer and carcinogenesis, either in intact form or after their enzymatic or nonenzymatic transformation in isothiocyanates and indolic compounds. There are more than 120 types of GSLs in Cruciferous plants which depending on their content and chemical structure may exhibit toxic, antinutritional, or beneficial effects to human health. Therefore, although GSLs in general are considered as “good” metabolites, there are cases where they are associated with toxicity effects, mainly regarding the hypertrophy of thyroid gland and the induction of goiter. In this chapter, an overview of the beneficial effects of GSLs is presented, while special focus is given on those cases where adverse effects and toxicities have been reported. Moreover, the means by which plant content in GSLs could be regulated to increase nutritional value of plant products and minimize toxicities risk are presented.