Glucosinolates human metabolism

Shapiro TA, Fahey JW, Wade KL, Stephenson KK, Talalay P. Human metabolism and excretion of cancer chemoprotective glucosinolates and isothiocyanates of cruciferous vegetables. Cancer Epidemiol Biomark Prev 1998 7 1091-1100. 

Humans metabolize isothiocyanates by conjugation with glutathione, and then subsequent metabolism is via the mercapturic acid pathway, and excretion, as mainly the N-acetylcysteine-isothiocyanate conjugates (Mennicke etal. 1983, 1988 Figure 2.5). The presence of N-acetylcysteine-isothiocyanate conjugates in urine provides a useful marker for isothiocyanate and glucosinolate consumption (Duncan etal. 1997 Chung etal. 1998 Sharpio et al. 1998 Rose et al. 2000). Epithionitriles are also metabolized in a similar manner (Brocker etal. 1984). 

SHAPIRO T A, FAHEY J w, WADE K L, STEPHENSON K K and TALALAY p (2001) Chemoprotective glucosinolates and isothiocyanates of broccoli sprouts metabolism and excretion in humans . Cancer Epidemiol Biomarkers Prev, 10 501-8. 

The Dutch-Danish 1991 philosophy paper highlighted that the Codex definition of a contaminant does not include inherent natural toxins (e.g. the glucosinolates and phycotoxins), since these substances are present in food as a result of the metabolic processes in the organism. It was then decided to have the GSCTF also to include such toxins, as they may in many ways be similar to contaminants. Many toxins are at least as toxic to humans as most contaminants, and they may also cause problems in international trade.10 It was also recommended and agreed by the CCFAC that the GSCTF should be based upon a horizontal approach, i.e. covering the important contaminants in all relevant foods, and that the MLs should be set as low as reasonably achievable - the ALARA principle. 

Fahey, J.W. and Talalay, R, Antioxidant functions of sulforaphane a potent inducer of phase II detoxication enzymes. Food Chem. Toxicol, 37, 973-979, 1999. Shapiro, T.A., Fahey, J.W., Wade, K.L., Stephenson, K.K., and Talalay, P. Chemo-protective glucosinolates and isothiocyanates of broccoh sprouts metabolism and excretion in humans. Cancer Epidemiol Biomarkers Prev., 10, 501-508, 2001. Faulkner, K., Mithen, R., and Williamnson, G., Selective increase of the potential anticarcinogen 4-methylsulphinylbutyl glucosinolate in broccoh. Carcinogenesis, 19, 605-609, 1998. 

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