Mounting evidence shows that the foods we eat weigh heavily in the war against cancer.
By Elizabeth Heubeck, MA
WebMD Weight Loss Clinic - Feature
Reviewed by Louise Chang, MD
As researchers continue to wage war against cancer, many have begun to focus on what could be the most promising ammunition to date: diet.
"The easiest, least-expensive way to reduce your risk for cancer is just by eating a healthy diet," says Rachael Stolzenberg-Solomon, PhD, MPH, RD, a researcher at the National Cancer Institute.
When it comes to a diet rich in cancer-fighting substances, most experts agree that it should consist of a predominantly plant-based diet. "If you have two-thirds of plant food on your plate, that seems to be enough to avoid excessive amounts of food high in saturated fat," says Karen Collins, RD, nutritional advisor for the American Institute for Cancer Research.
That seemingly simple advice could mean a drastic change in diet for many people.
"People who are thinking that this is like a diet, and are trying to choke this stuff down, it's never going to last," Collins tells WebMD. "You're looking at creating something for a lifetime. If it takes you awhile, but each month or so you enjoy [one more vegetable], then that's great," Collins.
You may want to start with some of the following food substances, all of which show promise as cancer-fighting agents.
This B-complex vitamin can be found in many 'good for you' foods. Plus, manufacturers of cereals, pastas, and breads often fortify their products with folate.
How It Works
"The thought is that when someone has low levels of folate, it's more likely for mutations in DNA to occur," Stolzenberg-Solomon says. Conversely, adequate levels of folate protect against such mutations.
In a large-scale study, researchers evaluated the effects of folate on more than 27,000 male smokers between ages 50 and 69. Men who consumed at least the recommended daily allowance of folate -- about 400 micrograms -- cut by half their risk of developing pancreatic cancer.
How to Get It
Starting with breakfast, a glass of orange juice is high in folate; so are most cereals (check the box to see how much). For lunch, try a hearty salad with either spinach or romaine leaves. Top it with dried beans or peas for an extra boost. Snack on a handful of peanuts or an orange. At dinner, choose asparagus or Brussels sprouts as your vegetable.
This fat-soluble vitamin which helps absorb calcium to build strong teeth and bones may also build protection against cancer.
How It Works
Researchers suggest that vitamin D curbs the growth of cancerous cells.
A report presented at the latest meeting of the American Association for Cancer Research (AACR) showed a link between increased vitamin D intake and reduced breast cancer risk. It found vitamin D to lower the risk of developing breast cancer by up to 50%.
Vitamin D may also improve survival rates among lung cancer patients, according to a Harvard study reported in 2005. Patients who received surgery for lung cancer in the summer, when vitamin D exposure from sunshine is greatest, and had the highest intake of vitamin D, reported a 56% five-year survival rate. Patients with low vitamin D intakes and winter surgeries had only a 23% survival rate.
How to Get It
In light of these recent findings, many researchers consider the current RDA of 400 international units (IU) too low. William G. Nelson, MD, PhD, of Johns Hopkins University in Baltimore, Md., suggests that the RDA recommendations for vitamin D be increased to 1,000 IU for both men and women. "Higher amounts may eventually prove better, but for now that amount is likely to be safe and have a protective effect," he tells WebMD.
While vitamin D is often associated with milk, high concentrations also can be found in these seafood choices: cod, shrimp, and Chinook salmon. Eggs are another good source. And don't forget sunshine. In just 10 minutes, you can soak up as much as 5,000 IU of vitamin D if you expose 40% of your body to the sun, without sunscreen.
If you enjoy sipping tea, you'll be happy to know that it appears promising against some forms of cancer.
How It Works
Like many plant-based foods, tea contains flavonoids, known for their antioxidant effects. One flavonoid in particular, kaempferol, has shown protective effects against cancer.
A large-scale study evaluating kaempferol intake of more than 66,000 women showed that those who consumed the most of it had the lowest risk of developing ovarian cancer. Researcher Margaret Gates, a doctoral candidate at Harvard's School of Public Health, suggests that consuming between 10 milligrams and 12 milligrams daily of kaempferol -- the amount found in four cups of tea --offers protection against ovarian cancer.
A separate study showed a link between consuming flavonoids and reducing the risk of breast cancer. The study, analyzing the lifestyle habits of nearly 3,000 people, showed that postmenopausal women who got the most flavonoids were 46% less likely to develop breast cancer than those who got the least. However, flavonoid consumption had no effect on breast cancer risk among premenopausal women.
How to Get It
Hot tea can be warming in the winter; ice tea offers cool refreshment in the summer. So enjoy tea year-round to boost cancer prevention.
They may not have been your favorite as a kid, but cruciferous vegetables -- members of the cabbage family that include kale, turnip greens, cabbage, cauliflower, broccoli, and Brussels sprouts -- can help you ward off cancer.
How They Work
In lab experiments, substances released during either cutting or chewing cruciferous vegetables produced a cancer-killing effect.
Recent studies on cruciferous vegetables show promising results against prostate and colon cancers. In mice grafted with human prostate tumors and then treated with one of these cancer-killing substances, tumors began to shrink to half their size after 31 days. In another experiment, mice engineered to be a model for an inherited colon polyp condition that is at high risk for developing into colon cancer were fed the antioxidant called sulforaphane, also released when chewing cruciferous vegetables. The mice developed about half as many polyps as expected.
How to Get Them
Swallowing them whole won't do. The protective effect of cruciferous vegetables seems to occur when they are cut or chewed. They're great in stir fry, as side dishes, or tossed into salads raw. Experiment with flavors like lemon or garlic. "Vegetables can be a fabulous-tasting centerpiece of cuisine," says Collins.
By sprinkling curcumin into your favorite dishes, you could be adding much more than a little zest to your meal -- you could add years to your life.
How It Works
Experts credit curcumin's anti-inflammatory effects for its ability to fight cancer. "Most diseases are caused by chronic inflammation that persists over long periods of time," says Bharat B. Aggarwal, PhD, a biochemist at The University of Texas M. D. Anderson Cancer Center. Recent studies have shown curcumin to interfere with cell-signaling pathways, thereby suppressing the transformation, proliferation, and invasion of cancerous cells.
Curcumin's protective effects may extend to bladder and gastrointestinal cancers. Some say they don't stop with these types of cancer. "Among all the cancers we and others have examined, no cancer yet has been found which is not affected by curcumin. This is expected, as inflammation is the mediator for most cancer," Aggarwal tells WebMD.
How to Get It
Curcumin flavors lots of popular Indian dishes, as it is the main ingredient in curry powder. It complements rice, chicken, vegetable, and lentils. Some chefs sprinkle the bright, yellow powder into recipes for a burst of color.
This popular spice, long used to quell nausea, may soon be used to fight cancer, too.
How It Works
Working directly on cancer cells, researchers discovered ginger's ability to kill cancer cells in two ways. In apoptosis, the cancer cells essentially commit suicide without harming surrounding cells. In autophagy, "the cells are tricked into digesting themselves," explains J. Rebecca Liu, assistant professor of obstetrics and gynecology at the University of Michigan in Ann Arbor, who has been studying ginger's effects on ovarian cancer cells. While this preliminary evidence shows promise, ginger's cancer-fighting effects must still be proven in animal and human trials.
Armed with ginger, ongoing research is taking aim against the most lethal of gynecological cancers: ovarian cancer. "Most women [with ovarian cancer] develop resistance to conventional chemotherapy drugs," Liu tells WebMD. Because ginger may kill cancer cells in more than one way, researchers are hopeful that patients would not develop resistance to it.
Because ginger's effects on cancer haven't been tested directly on human subjects, researchers can't yet offer specific dietary recommendations. "We don't know how it's metabolized," Liu says. But that needn't stop people from adding ginger to their diet. "We know it's relatively nontoxic," Liu tells WebMD.
How to Get It
Go beyond the obvious choices, like sipping ginger ale and eating gingerbread cookies. Countless soups, sumptuous marinades, and zesty sauces call for ginger.
Published April 24, 2006.
SOURCES: Rachael Stolzenberg-Solomon, PhD, MPH, RD, researcher, National Cancer Institute. Karen Collins, RD, nutritional advisor, American Institute for Cancer Research. Stolzenberg-Solomon, et al. American Journal of Epidemiology, 2001; vol 153: pp 680-687. Annual meeting of the American Association of Cancer Research, Washington, April 1-6, 2006. Annual meeting of the American Association of Cancer Research, Anaheim, Calif., April 2005. William G. Nelson, MD, PhD, Johns Hopkins University, Baltimore, Md. Bharat B. Aggarwal, PhD, biochemist, University of Texas M. D. Anderson Cancer Center. J. Rebecca Liu, assistant professor of obstetrics and gynecology, University of Michigan, Ann Arbor. WebMD Medical News: "Tea May Fight Ovarian, Breast Cancers." WebMD Medical News: "Crunchy Veggies Fight Cancer." WebMD Medical News: "Vitamin D May Protect Against Cancer." Zhou, W. Cancer Epidemiology & Biomarkers Prevention, October 2005; vol 14: pp 2303-2309. Magad, G. Anticancer Research, 2002; vol 22(6C): pp 4179-4181. Park C, et al. Oncology Reports, May 2006; vol 15(5): pp 1225-1231. Lev-Ari, S. Biomedicine & Pharmacotherapy, 2005; suppl 2: pp S276-S280.
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