Randomized Crossover Trial Evaluating Detoxification of Tobacco Carcinogens by Broccoli Seed and Sprout Extract in Current Smokers

Simple Summary: Cruciferous vegetable consumption is associated with reduced risk of tobacco-related cancers. Broccoli seed and sprout extract (BSSE) is rich in the isothiocyanate glucoraphanin, which is hydrolyzed to the phytochemical sulforaphane, a potent inducer of cytoprotective enzymes. This randomized, crossover trial evaluated detoxification of tobacco carcinogens by two doses of the BSSE Avmacol (R) in 49 otherwise healthy tobacco smokers. The higher dose (296 mu mol of glucoraphanin daily) significantly upregulated detoxification of benzene, acrolein, and crotonaldehyde. Consumption of cruciferous vegetables, rich in the isothiocyanate glucoraphanin, is associated with reduced risk of tobacco-related cancers. Sulforaphane, released by hydrolysis of glucoraphanin, potently induces cytoprotective phase II enzymes. Sulforaphane decreased the incidence of oral cancer in the 4NQO carcinogenesis model. In residents of Qidong, China, broccoli seed and sprout extracts (BSSE) increased detoxification of air pollutants benzene and acrolein, also found in tobacco smoke. This randomized, crossover trial evaluated detoxification of tobacco carcinogens by the BSSE Avmacol (R) in otherwise healthy smokers. Participants were treated for 2 weeks with both low and higher-dose BSSE (148 mu mol vs. 296 mu mol of glucoraphanin daily), separated by a 2-week washout, with randomization to low-high vs. high-low sequence. The primary endpoint was detoxification of benzene, measured by urinary excretion of its mercapturic acid, SPMA. Secondary endpoints included bioavailability, detoxification of acrolein and crotonaldehyde, modulation by GST genotype, and toxicity. Forty-nine participants enrolled, including 26 (53%) females with median use of 20 cigarettes/day. Low and higher-dose BSSE showed a mean bioavailability of 11% and 10%, respectively. Higher-dose BSSE significantly upregulated urinary excretion of the mercapturic acids of benzene (p = 0.04), acrolein (p < 0.01), and crotonaldehyde (p = 0.02), independent of GST genotype. Retention and compliance were high resulting in early study completion. In conclusion, BSSE significantly upregulated detoxification of the tobacco carcinogens benzene, acrolein, and crotonaldehyde in current tobacco smokers.