Dose-dependent detoxication of the airborne pollutant benzene in a randomized trial of broccoli sprout beverage in Qidong, China.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 31268126 · doi:10.1093/ajcn/nqz122
What was done
In a randomized, placebo-controlled, multidose trial conducted in Qidong, China, 170 participants were assigned to drink either a placebo beverage (n = 55) or one of three concentrations of a broccoli sprout beverage—full dose (n = 25), one-half dose (n = 35), or one-fifth dose (n = 55)—daily for 10 consecutive days. Mass spectrometry was used to measure 12-hour overnight urinary excretion of S-phenylmercapturic acid (SPMA), a biomarker of glutathione conjugation and detoxication of airborne benzene, as well as 24-hour urinary sulforaphane metabolites.
What was found
Median 24-hour urinary excretion of sulforaphane metabolites was 24.6, 10.3, and 4.3 µmol across the full-, half-, and one-fifth-dose groups, respectively. Participants in the full-dose broccoli sprout group showed a statistically significant 63.2% increase in urinary SPMA excretion over the 10-day period compared to placebo. The one-half dose (+11.3%) and one-fifth dose (-6.4%) groups showed no statistically significant differences from placebo.
Why it matters
This establishes a minimum effective dose threshold (equivalent to ~25 µmol daily urinary sulforaphane output) for sulforaphane-rich beverages to enhance the clearance of airborne benzene in exposed populations.
Limits
The intervention lasted only 10 days in a single geographic area with high baseline air pollution. The study evaluated an intermediate surrogate biomarker of detoxication (urinary SPMA) rather than clinical disease endpoints or long-term health outcomes.