CORVALLIS, Ore. - A new clinical study has found that inexpensive daily supplements of chlorophyllin can greatly reduce the DNA damage caused by aflatoxin contamination in the diet, and could provide a practical way to prevent thousands of cases of liver cancer in some parts of the world.
The research was recently completed in China by scientists from the Johns Hopkins Bloomberg School of Public Health and Oregon State University, and published today in the professional journal Proceedings of the National Academy of Sciences.
Chlorophyllin is a derivative of the natural chlorophyll found in green vegetables and commonly available as a dietary supplement. Aflatoxins, which are known carcinogens, are produced by a fungus that is a contaminant of grains such as corn, peanuts and soybeans. Levels of aflatoxin are carefully regulated in the United States but are often far higher in the food supply of many developing nations - and are known to cause liver cancer, especially in concert with other health problems such as hepatitis.
"In the area of China in which we did our study about one in 10 adults die from liver cancer, and it's the third leading cause of cancer deaths worldwide," said George Bailey, a distinguished professor of environmental and molecular toxicology at OSU. "The findings of this research could be enormously important to many areas of China, Southeast Asia and Africa where aflatoxin-related liver cancer is a real concern. Many of these deaths might be preventable with supplements that cost pennies a day."
The double-blind study was directed by Thomas Kensler, a professor of environmental health sciences at Johns Hopkins Bloomberg School of Public Health. In it, 180 healthy adults participated from Qidong, China, a region with extraordinarily high rates of liver cancer, due in part to a diet that has high levels of carcinogenic aflatoxins. Half the study participants were given 100 milligram tablets of chlorophyllin to take three times a day with meals for four months. The other half received a placebo. After that time, samples of urine and blood revealed levels of "damage byproducts" related to aflatoxin exposure, and provided an accurate picture of how much aflatoxin damage was being done in the study participants.
The study showed that people receiving chlorophyllin had 55 percent less DNA damage related to the aflatoxin exposure in their normal diet. According to Bailey, who directs the Marine-Freshwater Biomedical Sciences Center at OSU, research suggests that chlorophyllin acts as an "interceptor molecule" to block the absorption of aflatoxins and related carcinogens in the diet.
"We first uncovered this simple protective effect in cancer studies with rainbow trout, and the present results suggest that it will be equally effective in humans," Bailey said.
According to John Groopman, professor and chairman of the Department of Environmental Health Sciences at the Johns Hopkins School of Public Health, the "study shows that chlorophyllin can effectively reduce aflatoxin levels, which should reduce the risk of liver cancer. Since chlorophyllin can be easily added to the diet, it could be a safe and effective prevention method."
There is no evidence of any harmful effects from the amounts of chlorophyllin used as supplements in this study, Bailey said. It should also be noted, he said, that the chlorophyllin compound used in this research is a derivative of chlorophyll, and it's not yet proven whether the natural chlorophyll found in foods - especially the high levels found in dark green leafy foods such as spinach and broccoli - will provide the same protection from aflatoxins as the supplements did.
In some areas of the world, Bailey said, liver cancer is a major killer, and mortality from this disease is often related both to diet and disease. People with a high level of exposure to aflatoxin in their diet have four times the rate of liver cancer as control groups, and people who have had hepatitis have seven times the risk. People who have had both hepatitis and continued exposure to dietary aflatoxin have 60 times the normal rate of liver cancer.
There is no scientific evidence that chlorophyllin supplements can be used as an effective therapy for established liver cancer or any other cancer, Bailey said. However, his research group does want to study whether these compounds may have any value in protecting against colon and smoking-related lung cancer.
This human clinical trial grew out of earlier research at OSU during the 1990s which had shown similar results with trout exposed to aflatoxins, in which dietary chlorophyllin prevented 80 percent of the liver cancers that would otherwise have formed. In this research with trout, chlorophyllin appeared to have value as a cancer preventer only if it is present in the diet at the same time as the carcinogen.
Chlorophyllin, a stable derivative of chlorophyll, is often used as a food dye or in some medicines. Many experts at OSU, including several at the university's Linus Pauling Institute, are recognized leaders in the study of chemoprevention and phytochemicals such as chlorophyll, or dietary compounds and chemicals that may have the capacity to inhibit cancer.