Exogenous myrosinase from mustard seed increases bioavailability of sulforaphane from a glucoraphanin-rich broccoli seed extract in a randomized clinical study.

Exogenous myrosinase doubled the bioavailability of sulforaphane compared to gut microbial conversion alone.

• GR + Myr produced average SF bioavailability of 39.8 ± 3.1% compared to 18.6 ± 3.1% for GR alone
• Bioavailability was measured via urinary metabolites
• Study was a randomized, double-blind, crossover design with 16 subjects (9F:7M)
• Both conditions included ascorbic acid and involved a single oral dose

Exogenous myrosinase increased the early conversion rate of glucoraphanin to sulforaphane in the first 8 hours.

• GR + Myr condition showed a conversion rate of 25.4% ± 2.7% in the first 8 hours
• GR alone showed a conversion rate of only 8.0% ± 2.7% in the first 8 hours
• This indicates faster and more efficient early-phase conversion with exogenous myrosinase
• Measurement was based on urinary metabolites collected over the time course

A single oral dose of glucoraphanin did not alter fecal bacterial community composition.

• No differences in fecal bacterial communities were observed after the single dose
• This suggests that one dose of GR is insufficient to shift the gut microbiome
• The study used 16 subjects in a crossover design, allowing within-subject comparison
• Fecal microbial community analysis was conducted as part of the study protocol

Four bacterial glucoraphanin-converting genes significantly correlated with glucoraphanin conversion efficiency.

• Four bacterial GR-converting genes were identified as significantly correlated with GR conversion
• All four correlations reached statistical significance at p < 0.0155
• This finding suggests that baseline gut microbial gene content can predict responsiveness to GR
• The authors describe this as the first human study to simultaneously investigate prediction of gut microbial responsiveness to GR

This study used broccoli seeds as the glucoraphanin source and mustard seed powder as the exogenous myrosinase source.

• The glucoraphanin-rich supplement was derived from broccoli seed extract
• Myrosinase was supplied via mustard seed powder
• Both conditions were administered with ascorbic acid
• The authors state this is the first human study to simultaneously investigate a well-defined myrosinase source, broccoli seeds as the GR source, and prediction of gut microbial responsiveness to GR

Gut microbial myrosinase-like activity is variable and less efficient than exogenous myrosinase for sulforaphane conversion.

• Inactive glucoraphanin requires conversion by myrosinase from cruciferous vegetables or by similar enzymes from specific gut bacteria
• Both sources of myrosinase activity are described as having 'variable efficiency'
• GR alone (relying on gut microbial conversion) produced approximately half the SF bioavailability compared to GR + exogenous Myr (18.6% vs 39.8%)
• The study was designed to compare exogenous Myr to gut microbial Myr-like activity