Sulforaphane bioavailability and bioactivity in humans

Sulforaphane (SFN) is an isothiocyanate derived from cruciferous vegetables with many potential health benefits. However, there is limited knowledge about its bioavailability in humans. Crucifers contain glucoraphanin (GFN), which is hydrolyzed by myrosinase to yield SFN. Myrosinase is present within the plant, and a small amount is produced by gut bacteria. We previously observed a 7- fold decrease in SFN bioavailability from GFN supplements with inactivated myrosinase than from fresh broccoli sprouts, suggesting that the lack of myrosinase impacts SFN bioavailability. Goals of the present study were to determine the bioavailability and bioactivity of a myrosinase-treated broccoli sprout extract (BSE) supplement and broccoli sprouts. Participants consumed BSEs or broccoli sprouts once or twice a day (time 0 and 12h). SFN bioavailability from BSE was improved over myrosinase-inactivated GFN supplements but was still about 3 times lower than broccoli sprouts. Consuming SFN twice daily maintained plasma metabolite levels at 24 hours, suggesting that the twice daily dosing protocol resulted in longer retention of plasma SFN levels. Nrf-2 target genes and histone deacetylase activity were used to measure biological response to SFN treatment. This research provides important information for SFN supplement use in clinical trials. Funding: R01CA122906 & P01CA090890 Grant Funding Source: R01CA122906, P01CA090890