In a 1980 study, researchers dispensed daily chlorophyllin tablets to 62 female patients at a nursing home for six months. At the beginning, half of them were incontinent, with a strong smell; the other half struggled with constipation and flatulence. The first group reportedly improved by 85 percent and the second by 50 percent.

“It’s hard to objectively measure that effect,” said Dr. Timothy Gardner, a gastroenterologist and an associate professor of medicine at Dartmouth’s Geisel School of Medicine. Not only did this study lack a control group, he said, but it has not been replicated in the nearly 40 years since. He believes there was a large placebo effect and said there’s not enough evidence for chlorophyll or chlorophyllin’s use for constipation, flatulence or reducing body odors.

Another area where doctors say more research is needed is cancer prevention . Chlorophyllin may protect against aflatoxin, a toxin made by fungi and known to contaminate food in the area around Qidong, China. At the time of a 2001 study, it was a big problem there, since dietary exposure to aflatoxins increases the likelihood of developing hepatocellular carcinoma, a type of liver cancer.

In the randomized, double-blind, placebo-controlled trial, 180 residents of Qidong were told to take three pills a day, one before each meal. They either received three 100-milligram doses of chlorophyllin or three placebo pills. Urine samples showed that chlorophyllin consumption for four months was associated with a 55 percent reduction of the aflatoxin DNA damage biomarkers compared to those taking the placebo.

“The efficacy was demonstrated by the reduction in the DNA damage,” said John D. Groopman , the Edyth Schoenrich professor of preventive medicine at Johns Hopkins University’s Sidney Kimmel Comprehensive Cancer Center, and an author of the study. He added that there were no adverse effects. But the trial did not continue for a long period or examine whether rates of cancer decreased, he said.

While the work on aflatoxin was exciting when it emerged, T imothy R. Rebbeck , a professor of cancer prevention at Dana-Farber Cancer Institute, says that, without more data, there’s not enough of a link to warrant the widespread use of chlorophyllin by consumers. “I am not sure we could expect it to have an impact on any other population, or perhaps even any other cancer,” said Dr. Rebbeck in an email interview.