Sulforaphane Bioavailability from Glucoraphanin-Rich Broccoli: Control by Active Endogenous Myrosinase.
Level 3 - non-randomized controlled study
Comparative pharmacokinetic trial in human volunteers without explicit statement of randomization in abstract
PubMed 26524341 · doi:10.1371/journal.pone.0140963
What was done
Human volunteers received glucoraphanin via different formulations to evaluate sulforaphane bioavailability via urinary metabolite excretion. Comparisons included a commercial dietary supplement versus a boiled and lyophilized broccoli sprout extract (equimolar doses), as well as direct administration of broccoli sprouts or seeds containing active endogenous myrosinase versus preparations where myrosinase had been inactivated. Various delivery vehicles (fruit juices, teas, water, capsules, tablets) were also tested.
What was found
Urinary excretion of sulforaphane metabolites was equivalent between the commercial dietary supplement and the boiled/lyophilized broccoli sprout extract. However, when broccoli sprouts or seeds containing active endogenous myrosinase were administered directly, sulforaphane bioavailability was 3- to 4-fold higher than preparations containing glucoraphanin without active plant myrosinase, regardless of matrix or dose. Exact sample sizes and baseline excretion amounts were not quantified in the abstract.
Why it matters
Glucoraphanin requires conversion to sulforaphane to exert bioactivity. Demonstrating that intact endogenous myrosinase provides a 3- to 4-fold increase in bioavailability clarifies the critical role of enzyme preservation in broccoli-based supplements and functional foods.
Limits
The abstract describes only a small number of human volunteers and does not state the exact sample size, randomization method, or washout periods. Only urinary pharmacokinetic metabolites were tracked; clinical efficacy or tissue-level health outcomes were not evaluated.
Cited by
- supports Intact, freshly harvested broccoli and broccoli sprouts contain no free sulforaphane, only its precursor glucoraphanin.
- supports Supplements that pair glucoraphanin with active myrosinase have higher conversion efficiency and require lower doses of glucoraphanin than formulations relying solely on gut microbiome myrosinase.