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"Food Sources
Glucobrassicin, the glucosinolate precursor of I3C, is found in a number of cruciferous vegetables, including broccoli, Brussels sprouts, cabbage, cauliflower, collard greens, kale, kohlrabi, mustard greens, radish, rutabaga, and turnip (87, 88). Although glucosinolates are present in relatively high concentrations in cruciferous vegetables, glucobrassicin makes up only about 8-12% of the total glucosinolates (89). Total glucosinolate contents of selected cruciferous vegetables are presented in the table below (90). The amount of indole-3-carbinol formed from glucobrassicin in foods is variable and depends, in part, on the processing and preparation of foods.
Effects of Cooking
Glucosinolates are water-soluble compounds that may be leached into cooking water. Boiling cruciferous vegetables from 9-15 minutes resulted in 18-59% decreases in the total glucosinolate content of cruciferous vegetables (90). Cooking methods that use less water, such as steaming or microwaving, may reduce glucosinolate losses. Some cooking practices, including boiling (91), steaming (92), and microwaving at high power (850-900 watts) (93, 94), may inactivate myrosinase, the enzyme that catalyzes glucosinolate hydrolysis. Even in the absence of plant myrosinase activity, the myrosinase activity of human intestinal bacteria results in some glucosinolate hydrolysis (6). However, studies in humans have found that inactivation of myrosinase in cruciferous vegetables substantially decreases the bioavailability of glucosinolate hydrolysis products known as isothiocyanates (91-93). Since the formation of I3C also depends on glucosinolate hydrolysis, it is very likely that the bioavailability of I3C and its acid condensation products would also be decreased by myrosinase inactivation."
Zmieniony przez - s.m.p.a. w dniu 2011-05-16 20:14:54