OSU team to study food chemical link in cancer protection.

Byline: Tim Christie The Register-Guard

Scientists know that one in three cancers is related in some way to what we eat.

What they don't know is how exactly chemicals in food protect against certain cancers.

A trio of Oregon State University scientists have embarked on an ambitious five-year study to learn more about how some natural dietary compounds - in everything from green beans to green tea - guard against cancer in different animals, humans and even fetuses.

The wide-ranging study, funded by an $8.6 million grant from the National Cancer Institute, will look at how these chemicals work across a broad spectrum of biology - from basic cells to mice to trout to humans.

"Cancer chemoprevention is an extremely promising field, and there's enough evidence to support human clinical trials with some compounds right now," said George Bailey, a distinguished professor of environmental and molecular toxicology at OSU.

"But there's also a great deal more we need to learn about exactly what some of these compounds do, how they function and what types of people or types of cancer they may be appropriate for."

The grant will be used to combine the efforts of three major research programs, headed by Bailey and colleagues David Williams and Rod Dashwood, all part of the Linus Pauling Institute at OSU. A big reason they obtained the federal grant is that the researchers have a track record of working together in their different areas of research, Bailey said.

The researchers will focus on three chemicals: chlorophyllin, a derivative of the natural chlorophyll found in green vegetables; the polyphenols found in green and white teas; and indole-3-carbinol, a substance found in leafy vegetables.

Bailey's work with chlorophyllin has already attracted interest around the world. In an earlier study conducted in China, researchers found that inexpensive daily supplements of chlorophyllin greatly reduced the DNA damage caused by aflatoxin contamination in the diet.

Aflatoxin is a carcinogenic mold that contaminates grains, seeds, corn and nuts. It's a major health problem in some parts of China, where one in 10 adults die of liver cancer.

Evidence from Bailey's study suggests daily supplements of chlorophyllin could cut that mortality rate by more than half.

Bailey's new study will compare natural chlorophyll to the supplement chlorophyllin in a variety of laboratory, animal and human tests. Researchers will look at what mechanisms are involved and what types of cancer may be affected. Liver, colon and smoking-related cancers are of particular interest.

"Do natural chlorophylls have the same activity or similar activity as synthetic chlorophyllin? We'll know the answer to that question in five years," Bailey said.

Williams' research will examine the chemical indole-3-carbinol - found in broccoli, Brussel sprouts, cabbage and kale - and chlorophyllin. He'll look at how those chemicals may affect human and animal fetuses.

"We already know that fetuses can be fairly vulnerable to the toxic effects of carcinogens, which can cause cancer or birth defects and may relate to some miscarriages," he said. "So the question becomes, can we protect fetuses from chemicals that might cross the placental barrier."

He'll also study caffeinated and decaffeinated green tea with Dashwood to learn whether decaf provides the same cancer-preventing benefit as tea with caffeine. The question comes up because pregnant women are advised not to drink caffeine, Williams said.

Dashwood's study will continue his work in the preventive effects of green and white tea - both appear to lessen the risk of colon, small intestine and stomach cancer in animal studies.

Researchers want to learn how polyphenols - the chemical in certain teas believed responsible for protecting against cancer - work to prevent DNA damage from mutated cells. They also will study whether polyphenols can prevent previously mutated cells from progressing into cancer, especially in the gastrointestinal tract.

In all of this research, the scientists say they'll examine not only the potential benefits of the chemical compounds produced in plants but also possible risks.

"Many people take nutritional supplements with little or no scientific research to show what they will do," Bailey said. "We need to carefully examine both benefits and risks, understand how different phytochemicals may interact with one another, determine which ones provide protection against cancer and which might actually be harmful."

For instance, indole-3-carbinol, which is gaining popularity as a dietary supplement, is a "a dual-edged sword," Williams said.

"It can provide protection of some cancers, especially in the breast, but it can enhance the risk of liver cancer," he said.

Animal studies have shown that indole-3-carbinol can prevent cancer if taken before or during exposure to a carcinogen, Williams said. But if taken after carcinogen exposure, indole-3-carbinol can increase the risk of cancer.

"There are things in our diet that can enhance cancer risk and some that can reduce cancer risk," Williams said.