Bioavailability of Sulforaphane from two broccoli sprout beverages: results of a short-term, cross-over clinical trial in Qidong, China.
Level 2 - randomized trial
Randomized crossover trial in healthy volunteers
PubMed 21372038 · doi:10.1158/1940-6207.CAPR-10-0296
What was done
Fifty healthy participants in Qidong, China, were randomized into a crossover trial comparing two broccoli sprout beverages after refraining from cruciferous vegetables: a glucoraphanin-rich beverage (GRR, converted to sulforaphane by gut microflora) and a sulforaphane-rich beverage (SFR, pre-formed using daikon sprout myrosinase). The protocol consisted of a 5-day run-in, a 7-day beverage administration period, a 5-day washout, and a 7-day alternate beverage administration. Urinary levels of glucoraphanin, sulforaphane, and sulforaphane thiol conjugates were quantified from daily post-dose (~12-hour) urine collections using isotope dilution mass spectrometry.
What was found
Bioavailability, measured by urinary excretion of sulforaphane and metabolites, was substantially higher with SFR (mean = 70%) than with GRR (mean = 5%). Interindividual variability in excretion was considerably lower with SFR than with GRR. Elimination rates were considerably slower with GRR, resulting in steady-state dosing kinetics compared to bolus dosing kinetics with SFR.
Why it matters
Pre-hydrolyzing glucoraphanin with myrosinase enhances sulforaphane bioavailability fourteen-fold and bypasses variable gut microflora conversion. Understanding these contrasting kinetic profiles allows future chemoprevention trials to optimize formulations for either acute peak concentrations or prolonged steady-state exposure.
Limits
Bioavailability was assessed indirectly via ~12-hour urinary excretion rather than complete blood pharmacokinetics or tissue uptake. The study was conducted in a single geographic cohort of 50 healthy adults over short 7-day intervention periods and measured excretion rather than clinical or chemopreventive outcomes.
Cited by
- supports Human gut microbial conversion efficiency of ingested glucoraphanin ranges from a few percent up to 60 to 70 percent.