Dietary anti-cancer weapons get a boost

Studies confirm benefits of garlic, broccoli sprouts, cabbage

November 01, 2005|By JULIE BELL | JULIE BELL,SUN REPORTER

No one has proved that garlic wards off evil spirits, but scientists meeting here on Halloween presented new evidence that it might play a role in preventing cancer.

They also heard the latest findings suggesting that a diet rich in broccoli sprouts could reduce your chances of getting gastric cancer.

Want another way to cut your risk of breast cancer? Consider three servings a week of raw or lightly cooked sauerkraut and cabbage.

It's too early to say what all this means; scientists say much more research on diet and cancer is needed. But many among the more than 800 people assembled in Baltimore yesterday for the Frontiers in Cancer Prevention Research meeting seemed to agree on one easily digestible bit of advice: Eat your vegetables.

"Consistent consumption of fruits and vegetables is generally helpful, while red meat is generally not as helpful," said Dr. William G. Nelson, a Johns Hopkins University oncology professor who is chairing this week's conference, sponsored by the American Association for Cancer Research.

For years, scientists have been accumulating evidence that what we eat and how we prepare it can play a role in preventing or causing cancer. Yesterday's findings added punch to previous research finding that cruciferous vegetables - such as broccoli, cabbage, kale, collard greens and cauliflower - have cancer-fighting properties.

The Black Women's Health Study, which relied on a questionnaire of dietary patterns and other potential risk factors for 57,877 black women, found that those who were not obese and ate the most foods from a "prudent diet" (high in those vegetables but low in meat, eggs, refined grains and french fries) had the smallest risk of cancer.

What the studies released yesterday did not clarify was how much calcium-rich milk and cheese to consume. Although calcium has long been associated with positive effects such as strong bones, research unveiled yesterday found that men who took more than 2,000 milligrams of calcium per day nearly doubled their risk of prostate cancer.

Lead researcher Panagiota Mitrou of the National Cancer Institute said scientists need to find out why calcium might trigger prostate cancer in some men but not in others.

So what do yesterday's findings suggest that we should eat?

Garlic. At least, that's what lab tests conducted by Ronald D. Thomas, an environmental toxicologist from Florida A&M, suggested.

Scientists have shown that cooking meat at high temperatures can release a suspected carcinogen known as PhIP. Other studies have shown that a chemical that helps give garlic its flavor can keep PhIP from triggering DNA damage or the formation of carcinogens in the body.

Thomas' study suggests that the garlic flavor component - called DAS - triggers a gene alteration in PhIP that might play a role in preventing breast and other cancers.

So does Thomas think we should eat more garlic?

"I suggest they take garlic supplements if they don't want to take it in their food," he said, adding that people should also eat more fruits and vegetables and less meat.

Broccoli sprouts (We're not talking about grown-up broccoli, but the fluffy, newly germinated seeds that are two to three days old).

Research has shown that sprouts are good source of sulforaphane, a chemical shown in the laboratory to kill a bacteria that likely contributes to stomach cancer, peptic ulcers and gastritis. Yesterday's results marked the first time those findings had been tested in humans infected with the bacterium Helicobacter pylori.

Twenty subjects ate 100 grams of fresh broccoli sprouts (3.5 ounces) a day for two months. Twenty others ate the same quantity of alfalfa sprouts, which are not sulforaphane-rich.

Urine and stool samples from the broccoli sprout eaters showed they had significantly lower levels of a chemical that indicates gastritis. They also showed fewer H. pylori bacteria, although the bacteria weren't eliminated. The alfalfa sprouts had no effect.

Lead researcher Akinori Yanaka of the University of Tsukuba, Japan, plans more tests, including some using a smaller quantity of sprouts. But he had good news for anyone who wants to try the diet now.

"Nobody complained it was too much," he said, indicating that 100 grams of sprouts is no more than can be held in a giant mound in one hand.

That points to an advantage of eating the food itself, rather than a supplement extracted from it, said Jed W. Fahey, a Johns Hopkins University researcher who discovered sulforaphane's antibiotic effect in a test tube.

"You're not going to be able to overdose on broccoli, because you'll get too full and bloated," he said. "With supplements, you can eat too much."

Cabbage. Researcher Dorothy Rybaczyk-Pathak of the University of New Mexico wondered why the risk of breast cancer among Polish women who immigrated to the United States rose threefold after they arrived. She and researchers from Michigan and Warsaw theorized that diet might be a cause.

Like other cruciferous vegetables, cabbage contains glucosinolates, which have been linked with anti-cancer effects when they're broken down by chewing or cutting. Polish women eat about 30 pounds of cabbage and sauerkraut a year; American women eat only 10.

Their research, conducted via survey, found that Polish immigrants in Detroit and Chicago who still ate three or more servings a week of raw or lightly cooked cabbage and sauerkraut had a lower risk of breast cancer than those who ate less than one serving.

What if you think you won't like raw cabbage mixed with sauerkraut?

"I would recommend culturally specific ingestion of foods," Rybaczyk-Pathak said. "In America, we don't have high consumption of coleslaw. Why not eat more of it, even in teenagers? They could just be reducing breast cancer risk many years from now."

juliana.bell@baltsun.com

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