Watercress appears to improve the body’s response to some of the carcinogens in cigarettes, suggesting it could reduce cancer risk in smokers, according to a new University of Pittsburgh Cancer Institute study.
When taken four times a day, an extract of the aquatic plant species slightly inhibited the activation of a tobacco-specific carcinogen known as NNK in smokers, according to study results. Dr. Jian-Min Yuan, the study’s lead author, presented phase 2 trial results Tuesday in New Orleans at an American Association for Cancer Research meeting.
The extract also helped smokers detoxify two other carcinogens found in cigarettes, according to the results.
Watercress is a cruciferous vegetable, a group that includes broccoli, cabbage, turnips and other roots and greens. It has the highest concentration in the group of a compound called 2-Phenethyl isothiocyanate, or PEITC, Yuan said.
In the study, 82 smokers took four 10-milligram doses per day of a PEITC concentrate for a week and took a placebo for another week, he said. Participants on average were 41 years old and smoked 19.1 cigarettes per day. Researchers analyzed participants’ urine samples to determine how their bodies processed the carcinogens.
The extract reduced activation of the tobacco-specific carcinogen by an average of 7.7 percent, an outcome the study describes as modest.
The extract’s effect on how the body processes the others was more marked: the compound increased the detoxification of benzene by 24.6 percent and the detoxification of acrolein by 15.1 percent. The extract had no effect on detoxification of a third measured carcinogen, crotonaldehyde.
Supplements of PEITC don’t yet exist, Yuan said. He said participants consumed the equivalent of about 2 ounces of watercress per day. Eating the vegetable each day should confer similar benefits, he said, but acknowledged how impractical that might be.
“It may be difficult for the population to consume two ounces a day of watercress, because it is not very good. It’s a bit bitter,” he said.
The study, which was supported by the National Cancer Institute, cost $4 million and took about five years to complete, he said. Results are set to be published in two papers the next few weeks in the journal Cancer Prevention Research, he said.
The study was limited by its small sample size, short duration and small doses of PEITC, Yuan said. Researchers in the future could evaluate effects of larger doses taken over a longer period of time, he said.
Wes Venteicher is a Tribune-Review staff writer. Reach him at 412-380-5676 or [email protected].