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Wednesday, Nov. 9, 2005

NATURAL SELECTIONS

EAT YOUR GREENS!

Study finds broccoli combats gastritis


As futurists get excited by the prospect of engineering ourselves to have longer lives, it's easy to forget that, as well as the high-tech ways, there are very simple ways to live longer.

People in the Mediterranean, who are renowned for their health despite their wine intake, and people in Okinawa, who live longer than anyone else in the world, have not been using gene therapy and nanotechnology to reach old age healthily. They've done it through a combination of low stress, a well-connected community, and healthy food.

Finding out which of those foods is or isn't good for you is another matter. What is folklore and what is just good luck? Even based on scientific evidence, the list of things we should and shouldn't eat keeps changing. Red wine is OK one week, not the next.

But last week at the fourth annual Frontiers in Cancer Prevention Research meeting in Baltimore, Md., researchers presented the latest evidence on what to add to your diet to prevent or even halt the growth of cancer. The good news is that benefits will accrue at any stage of life. So if you've been eating badly until now, it's still not too late.

Broccoli, already a favorite with physicians, comes out especially good at preventing cancer.

Akinori Yanaka from the University of Tsukuba, in Ibaraki Prefecture, fed broccoli sprouts to a group of 20 people and found that the diet significantly reduced Helicobacter pylori (H. pylori) infection among them. H. pylori is the notorious bug that causes gastritis and is believed to be a major factor in peptic ulcers and stomach cancer. It is helical in shape (hence the name) and screws itself into the lining of the stomach.

Japanese people have about six times the rate of stomach cancer compared to people in the United States. Though the causes are not known (Japanese Americans have intermediate rates), they are likely to include the eating of salted foods and heavy smoking.

"Even though we were unable to eradicate H. pylori, to be able suppress it and relieve the accompanying gastritis by means as simple as eating more broccoli sprouts is good news for the many people who are infected," said Yanaka, lead investigator of the study.

So broccoli sprouts now join the list of foods thought to have cancer-busting properties. Something they all have in common, be it green tea, wine or tomatoes, is that they contain a good supply of antioxidants. Oxidants are the highly reactive molecules that damage DNA, potentially leading to cancer. Broccoli sprouts contain sulforaphane, which has been shown to mop up oxidants and attack H. pylori.

Yanaka's trial is worth mentioning here because it properly tested the purported protective benefit. While 20 people ate 100 grams of fresh broccoli sprouts daily (and they ate the plant at its youngest and most sulforaphane-rich, when it was just two or three days old) another 20 people ate 100 grams of alfalfa spouts instead.

"We wanted to test alfalfa spouts together with broccoli sprouts," Yanaka explained, "because the chemical constituents of the two plants are almost identical."

However, the way in which they differ is significant. Broccoli sprouts contain 250 milligrams of sulforaphane glucosinolate per 100-gram serving, whereas alfalfa sprouts contain neither sulforaphane nor sulforaphane glucosinolate. Sulforaphane's reported anticancer properties and its antioxidant effects are due to its ability to make cells make enzymes called "phase 2" enzymes. These are thought to offer protection against cancer by blocking chemicals that can act as carcinogens.

Glucosinolates occur in cruciferous vegetables, like broccoli and cabbage, and are broken down into sulforaphane when damage occurs to the plant. In other words, when you chew it.

After two months of the treatment, the 20 patients who'd been eating broccoli had less H. pylori and less of the enzyme pepsinogen, the presence of which indicates that damage is being done to the stomach lining. (Interesting bit of trivia: The cola drink Pepsi gets its name from pepsin, a stomach enzyme used to digest food, which itself is derived from pepsinogen. The original idea for Pepsi being that it cures stomach pains.)

Back to Yanaka's experiment. Two months after the tests stopped, the scientists found that both the experimental and the control groups had the same amount of H. pylori and pepsinogen as when they started.

"The data suggest strongly that a diet rich in sulforaphane glucosinolate may help protect against gastric cancer, presumably by activating gastric mucosal antioxidant enzymes that can protect the cells from H. pylori-induced DNA damage," Yanaka concluded.

So there we have it, a scientific study that has tested the benefits of a "cancer-busting" food and given reliable results. If only all such claims made for foods and drinks and pills and remedies said to ward off cancer were reliable.

A book of Natural Selections columns translated into Japanese, "Nou to sekkusu no seibutsugaku (Evolution, Sex and the Brain)," is published by Shinchosha. Rowan Hooper is a biologist at Trinity College, Dublin. He welcomes readers' comments at rowan.hooper@tcd.ie


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