Wednesday, April 21, 2004
Knight Ridder Newspapers

As berry season rolls in, consider that those juicy treats may be good for more than jams, cobblers and shortcakes.

They might also help prevent cancer, especially if you gobble up a pound of them a day.

Little raspberries, strawberries and blackberries appear to have big potential for cancer protection, an Ohio State University researcher told the annual meeting of the South Carolina Alliance for Cancer Chemoprevention recently.

Berries are just one ingredient among recipes for cancer prevention that are being studied, a National Cancer Institute representative told the group.

"Thirty to 35 percent of cancers are related to dietary factors," said John Milner, chief of the natural-products division of the cancer institute's cancer-prevention program.

Chemoprevention uses foods, drugs or dietary supplements to prevent invasive cancer by intervening in its early stages. The federal government finances $204 million in cancer/nutrition projects, so many compounds are in various stages of study, Milner said.

For example, drinking tea "inhibits cancers of many different sites, at least if you're a rat," Milner said.

Rodents also were the early beneficiaries of the berry research explained by Gary Stoner, director of Ohio State's cancer chemoprevention program.

Stoner said that since the early 1980s, scientists have known about the cancer-prevention potential of ellagic acid, an antioxidant found in many foods. A challenge was to find foods in which the element was concentrated and from which the body could absorb it.

It turned out that strawberries and raspberries were rich sources of ellagic acid and several other nutrients thought to protect against cancer. The Ohio researchers developed a process to have berries grown, freeze-dried and then pulverized into a powder they mixed with rats' normal food.

Evidently it pleased the rodents' taste buds, as most gained weight after eight months of the berry-enriched food. Their blood cholesterol was 15 percent lower, and researchers observed no toxic effects.

Testing further for cancer prevention, the researchers found:

-- Strawberries and black raspberries reduced the incidence of esophageal cancer.

-- Black raspberries and strawberries suppressed esophageal tumors.

-- Black raspberries also suppressed colon cancer tumors.

-- Berries did not seem to help prevent lung cancer in mice.

The Ohio researchers gave a small group of people the equivalent of two pounds of berries a day for two weeks, testing for toxic effects. None appeared. Now they are studying another group of volunteers who consume about a half-cup of berry powder mixed with water every day, the equivalent of a pound of fresh berries.

Stoner does not advise that the average person eat that many berries. But he said the research emphasized benefits from consuming more fruits and vegetables.

"We would suggest, based on our studies, that people eat five to nine helpings of fruits and vegetables per day, and it would be wise to include two to three helpings of berries per week," he said. (A helping is 4 ounces.)

The meeting at the University of South Carolina drew about 130 cancer researchers from around the state. The South Carolina Alliance for Cancer Chemoprevention, based at USC's School of Pharmacy, sponsors seminars and is leading collaborative research among the state's three research universities.

Clemson University researcher Lyndon Larcom also works with raspberries. A Myrtle Beach dermatologist is using a raspberry cream he helped develop to treat early stage skin cancer.

Larcom now seeks financing for an animal study to see whether muscadines, which grow well in South Carolina, have similar potential.

At the Medical University of South Carolina, Thomas Walle studies the potential of isoflavones, found in foods such as apples and soy, to protect against deadly oral and esophageal cancers.

USC's Michael Wargovich has focused on colorectal cancer prevention, working with substances including ginseng, curcumin and garlic.

And Palmetto Health's South Carolina Cancer Center is among the sites for the SELECT clinical trials to see whether the nutrients selenium and vitamin E protect against prostate cancer.

Using nutritional strategies to prevent cancer is complicated, Milner said.

Time of harvest, plant maturity and growing conditions influence the effects of foods, he said: "Not all broccoli is created equal."

Food interactions are another factor, he said, citing the example that drinking tea and eating soy appear to reduce tumors more when done at the same time than when done separately.

Different people respond in individual ways to different foods, just as they do to drugs, he said.

In the future, a serious approach to cancer chemoprevention may well include genetic testing to sort out those differences, Milner said.

"I call it pre-emptive nutrition -- introducing the right intervention at the right time," he said.

Also needed are studies of potential side effects, he said. For example, eating a lot of garlic -- six cloves -- has been linked with gastrointestinal bleeding.