WASHINGTON (AP) - Edible berries found on bushes that are planted along roads and streams to prevent soil erosion are far richer than tomatoes in a substance thought to help in preventing some cancer.

The fruit from the autumn olive plant resembles a small cranberry. Agriculture Department scientists who studied the fruit say the berries have as much as 18 times more lycopene than tomatoes.

"I was really surprised," said Beverly Clevidence, who runs the department's Phytonutrients Laboratory near Washington. "It's rare to see lycopene in anything that's not tomato-based."

In parts of Asia, the berries are eaten as a fruit. Clevidence analyzed the nutritional content of the berries at the request of Ingrid Fordham, a department horticulturist who begin studying the fruit about eight years ago.

The two wrote a report on their findings that is to be published next month in the journal of the American Society for Horticultural Science.

Lycopene is one of a group of chemicals, called antioxidants, that attack roaming oxygen molecules, known as free radicals, that are suspected of triggering cancer. Lycopene has been linked to lower rates of prostate and other cancers.

"I love them," said Fordham, who makes jams and jellies from the berries.

"The plant is very common around here, but no one has ever eaten the berries, or at least not commonly."

Autumn olives, which thrive in poor soil, are sometimes grown as a food source for wildlife. Many people, however, consider the plant a pest because it spreads when birds eat the berries and scatter the seeds, Fordham said. For that reason, she doubts the autumn olive would ever catch on in the United States as a food crop.

She made 30 jars of jam from berries she gathered last fall in rural Maryland. She keeps the location to herself. "I'm not going to divulge my secret, but they're easily found if you know what it looks like," she said.

Scientists are working on ways to increase the levels of antioxidants in fruits and vegetables. They are not sure how the chemicals work in relation to other nutrients in food or how much is needed for cancer protection.

"Eating a whole variety of plant-based foods is the key to getting these phytochemicals that we need," said nutritionist Melanie Polk of the American Institute for Cancer Research.

Autumn olive berries could provide a new source of lycopene for people who do not like tomatoes or might be used in dietary supplements, Clevidence said.

Tomatoes contain about 3 milligrams of lycopene per 100 grams, while autumn olives can have 15 milligrams to 54 milligrams, depending on the variety. Processed tomato products are much higher in lycopene. Tomato paste, for example, has 30 milligrams.

Further study will be needed to make sure the body absorbs lycopene from autumn olive berries.

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