Simple foods carry the most scientifically advanced anticancer compounds, scientists say.
The reports come from the fourth annual Frontiers in Cancer Prevention Research meeting, held by the American Association for Cancer Research.
At the cutting edge of these new frontiers is the finding that, well, that your mother was right. You really should eat your vegetables. They're full of newly discovered cancer-fighting compounds, says conference program chairman William G. Nelson, MD, PhD, of Johns Hopkins University.
"Basic research is discovering more and more about the cancer-preventing properties of things we are eating," Nelson said at a news conference. "The idea of having more fruits and vegetables in the diet has more and more evidence to support it."
This year a Nobel Prize went to the scientists who in 1982 discovered H. pylori, the bacterium that causes most stomach ulcers. But stomach ulcers aren't all this nasty bug does to us.
H. pylori causes a condition called gastritis, in which the walls of the stomach become red and swollen. Gastritis enormously increases a person's risk of stomach cancer.
A compound called sulforaphane protects cells from injury. It also happens to kill H. pylori. As it turns out, there is a natural source bursting with sulforaphane: broccoli sprouts. Yes, the compound can be found in small amounts in regular, mature broccoli. But broccoli sprouts are by far the best source, says Akinori Yanaka, MD, PhD, of the University of Tsukuba, Japan.
Broccoli Sprouts: Eat Them
Yanaka's team first fed the sprouts to H. pylori-infected mice. As long as the mice kept eating the sprouts, they kept the ulcer bug at bay.
Then they studied 50 people with H. pylori infection. Half ate about 3.5 ounces of broccoli sprouts every day for two months. The other half ate alfalfa sprouts, which have almost exactly the same nutrients but totally lack sulforaphane.
"Only the broccoli-sprout group had significantly decreased H. pylori activity," Yanaka said at the news conference. "Only those who ate broccoli sprouts showed decreased gastritis. We concluded that eating broccoli sprouts offers a rich source of sulforaphane, which may be useful as a chemoprotection against gastric cancer."
The broccoli sprouts did not cure H. pylori infection, however. The bug roared back two months after patients stopped eating the sprouts.
Broccoli Sprouts: Rub Them on Your Skin
Broccoli sprouts aren't just good for your insides. They're good for your outside, too, reports Johns Hopkins researcher Albena T. Dinkova-Kostova, PhD.
Dinkova-Kostova and colleagues found that an extract made from broccoli sprouts protects the skin of hairless mice exposed to cancer-causing ultraviolet light.
The skin rub isn't a sunscreen. Treated mice got just as much UV light as untreated mice. But while all the untreated mice got cancer from the simulated sun exposure, half the mice rubbed with broccoli-sprout extract remained cancer free. Those that did get cancer had half as many tumors as untreated mice.
"Broccoli-sprout extract could possibly be used as a preventive treatment for skin cancer after exposure to UV light," Dinkova-Kostova said at the news conference.
Cabbage: Eat It Raw
Polish women are more likely to get breast cancer if they emigrate to the U.S. Why, wondered Dorothy Rybaczyk-Pathak, PhD, of the University of New Mexico. She guessed it must have something to do with changing dietary habits.
A likely suspect: cabbage. Polish women traditionally consume 30 pounds of cabbage a year -- much of it in the form of raw sauerkraut, in salads, or in short-cooked side dishes. When they emigrate to America, they eat only 10 pounds of cabbage a year.
Cabbage -- like broccoli, kale, Brussels sprouts, collard greens, and cauliflower -- is a cruciferous vegetable. When broken down by chewing, cabbage releases several biologically active products including compounds called glucosinolates and an enzyme called myrosinase. These products have anticancer properties.
For the greatest benefit, timing seems to be crucial. Rybaczyk-Pathak found that women who as teenagers ate the most raw cabbage were least likely to get breast cancer. But even women who didn't eat much cabbage as teens had a lower breast cancer risk if they ate a lot of raw cabbage as adults.
How much cabbage need a woman eat? Three or more servings a week of raw or short-cooked cabbage puts a woman in the lowest risk category.
Unfortunately, traditional long-cooked Polish dishes such as hunter's stew, pierogi, and cabbage rolls did not lower cancer risk.
Garlic Wards Off Cancer
Vegetables fight cancer. But meats cooked at high temperatures -- as in grilling or frying -- contain a cancer-causing chemical called PhIP.
A compound called diallyl sulfide or DAS is one of the things that gives garlic its pungent flavor. Now researchers led by Ronald D. Thomas, PhD, of Florida A&M University, Tallahassee, report that DAS counteracts the cancer-causing actions of PhIP.
In the lab, Thomas and colleagues added PhIP, DAS, or both to human breast cells. Sure enough, PhIP made the cells secrete high amounts of cancer-causing enzymes. But PhIP completely protected cells from this effect.
It's a long way from the test tube to the human diet. But if garlic protected humans at the same dose at which it protected cell cultures, Thomas says garlic would have to make up one one-thousandth of your diet.
SOURCES: Meeting of Frontiers in Cancer Prevention Research, American Association for Cancer Research, Baltimore, Oct. 30-Nov. 2, 2005. ACR news conference: William G. Nelson, MD, PhD, Johns Hopkins University, Baltimore; Akinori Yanaka, MD, PhD, University of Tsukuba, Japan; Albena T. Dinkova-Kostova, PhD, Johns Hopkins University, Baltimore; Dorothy Rybaczyk-Pathak, PhD, University of New Mexico, Albuquerque; and Ronald D. Thomas, PhD, Florida A&M University, Tallahassee.