A watercress drink increases detoxification of common environmental carcinogens such as acrolein and benzene: results of a randomized clinical trial

Human exposure to toxicants and carcinogens occurs via polluted air, the diet, occupational settings, endogenous processes, and tobacco products. The glutathione-S-transferase detoxification pathway resulting in the excretion of mercapturic acids is one of the most important human systems for processing and excreting toxicants and carcinogens. Maximizing effectiveness of this pathway through dietary modifications can potentially decrease the impact of such exposures. We conducted a two-site clinical trial with a crossover, single blind (to participants) design, randomized to order of product receipt comparing levels of selected urinary mercapturic acids when participants consumed a drink made from freeze-dried watercress (3× daily, 2 weeks) naturally containing 2-phenethyl isothiocyanate (PEITC) vs. a placebo drink containing maltodextrin (3× daily, 2 weeks) with a 4-week washout between the treatment periods. Two hundred forty participants (157 F) were recruited and 188 (125 F, 152 non-smokers) were compliant and completed the study. Among compliant subjects, urinary mercapturic acid detoxification products of acrolein, acrylonitrile, benzene, crotonaldehyde, methacrolein, and methyl vinyl ketone increased significantly (P ≤ 0.002), with the largest increases being observed for the mercapturic acids of acrolein (65.6%) and benzene (37.3%), both P < 0.001. Consumption of a drink, three times daily, prepared from freeze-dried watercress containing PEITC (total of approximately 40 mg/day) significantly increased the detoxification of 6 of 7 environmental toxicants and carcinogens monitored. The results indicate that watercress consumption can ameliorate exposure to environmental toxicants and carcinogens. These results are particularly timely and relevant to exposures to atmospheric pyrolysis products resulting from wildfires. Clinical trial registration number: NCT03978117.