The Cancer-Fighting Diet

The statistics are downright scary. Cancer takes the lives of more than 550,000 Americans each year. The nation’s second leading killer after cardiovascular disease, it will strike one out of every three American women and half of all American men at some point during their lives.

The good news is that you can locate some highly effective tools to help lower your risk for many types of cancer right in your cupboard, refrigerator, or grocery store.

The links between what you eat and your risk for cardiovascular disease and/or diabetes have been known for some time. Now, a growing body of scientific evidence shows that dietary improvements can also significantly reduce your odds of developing certain forms of cancer. In fact, the National Cancer Institute’s (NCI) Division of Cancer Prevention estimates that 35 percent of cancer-related deaths could be prevented if Americans ate a healthier diet.

Where to Start

If you’re overweight, begin your fight against cancer by fighting the battle of the bulge. Two-thirds of the U.S. population weighs more than it should -- a risk factor for many types of cancer that is being more extensively documented every day.

According to the American Cancer Society, an overweight woman has a 60-percent greater risk for contracting endometrial cancer than a person of normal weight; that risk jumps to 152 percent for an obese woman. Being overweight increases the risk of breast cancer by 12 percent, and cancers of the kidney and gallbladder by 78 percent.

Duke researchers have also led studies that suggest that obese men are at greater risk for more aggressive prostate cancer.

Even after cancer is diagnosed, body weight can play a role in determining the course of the disease. For example, a woman who is overweight when she is diagnosed with breast cancer has twice the rate of disease recurrence as a woman of normal weight at the time of diagnosis.

So one of your best defenses against cancer is to maintain a healthy weight throughout life. And there's only one way to achieve that goal: eat less and exercise more.

Simple, yes -- but definitely not easy. In our “super-size” society, portion control is an ongoing challenge for many seeking to lose weight. “Take the typical pasta dinner,” says Denise Snyder, MS, RD, a nutrition scientist and clinical trials manager in the Duke University School of Nursing.

“A serving of pasta is figured by dietitians and food manufacturers as one-half cup. So someone who eats a plate of pasta at a restaurant is actually consuming six to eight servings. It could even be more than that.”

Another problem is the sedentary lifestyle most Americans lead. "In the 1860s, women ate 4,000 calories a day," Snyder says. "And they didn't struggle with the weight issues today's women face."

These days, however, the American lifestyle -- with its couch-potato recreational habits and suburban sprawl -- is much more sedentary. Combine that with an endless supply of high-calorie, low-quality food, and you've got a recipe for trouble.

Fewer than 20 percent of American adults are very active, according to a study by the Centers for Disease Control and Prevention, while one in four engage in little or no regular physical activity.

While exercising for a half-hour a day most days of the week may improve cardiovascular health, the Institute of Medicine of the National Academy of Sciences recommends an hour a day of physical activity five days a week to reduce cancer risk. One way to accomplish that, says Snyder, is to strap on a pedometer and try to incorporate 10,000 steps into your daily routine.

Plants Are Powerful

Whether you need to lose weight or simply maintain a healthy weight, the foods you choose can also have a dramatic impact on cancer risk.

At the centerpiece of the cancer-fighting diet are fruits and vegetables. Research suggests that people who eat at least five servings of fruit and vegetables per day have half the cancer risk of those who eat one serving a day or less. Today, it’s recommended that women eat seven servings a day, while men should aim for nine.

The NCI estimates that raising fruit and vegetable consumption to the recommended level nationwide could cut the incidence of colorectal cancer in half, reduce breast cancer cases by one quarter, and cut the number of cases of cancer of the prostate, endometrium and gallbladder by 15 percent.

According to Snyder, scientists are still not sure why fruits and vegetables provide such potent protection. She points out that, while these foods are packed full of vitamins and minerals, simply taking multi-vitamins and supplements does not offer the same benefits.

"Maybe it's a synergy between all the micronutrients in healthy foods, many of which have not yet been identified," Snyder says. "Maybe it's the fiber. Or maybe it's not only what people are eating, but what they're not eating that makes the difference. Vegetables are very low calorie. If you eat more of them, you're going to probably feel fuller and eat less high-protein fats."

Whatever the mechanisms, the results have been proven repeatedly. So Snyder recommends that, rather than stock up on expensive vitamins, people seeking to lower their cancer risk should stock up on healthful foodstuffs instead. She advocates a plant-based diet low in red meat and saturated fats (fats from animal sources) and high in fruits, vegetables, and whole grains.

Yes, grains. With the recent popularity of carbohydrate-lowering diets, some people have sworn off carbohydrates of every sort. But whole grains -- complex carbohydrates that are low in fat and high in fiber -- behave very differently within the body than “white” foods such as refined starches and sugars do.

Color alone, however, is not an indicator of nutrition, Snyder warns. Though supermarket aisles are filled with myriad types of brown breads, some are simply white bread with caramel coloring. So everyone looking for better nutrition needs to become a label reader, on the lookout for the fine print that will separate the wheat from the chaff.

If whole-wheat flour is the first ingredient listed on a bread, muffin, or bagel package label, the product is made from whole grain. Any other first ingredient indicates it’s not. The same goes for cereal boxes.

What to Avoid

As for those refined carbohydrates -- the ones found in sweetened cereals, cakes, pastries, and soda -- they provide little nutrition and lots of calories. So the less of them you consume, the better off you’ll be.

Try not to sink your teeth into too much red meat, either. Just one portion of red meat a day increases the risk of colorectal cancer by 25 percent.

And that’s an official-sized portion of only three ounces -- the size of a deck of cards. For those not willing to go completely vegetarian, Snyder suggests eating more poultry and fish and less beef, pork, or lamb.

An important component of the link between meat and cancer, Snyder says, is the correlation between cooking methods and increased risk. Poaching, microwaving and baking are preferable to frying, charbroiling, and other flame-broiled methods.

The closer the meat is to the heat source (and thus the higher the temperature at which it’s cooked), the more likely it is to form carcinogenic hydrocarbons that damage human DNA.

Those beers you might be tempted to chug at that burger cookout can further dilute your resistance to cancer. People who regularly consume several alcoholic beverages a day have a greater chance of contracting cancers of the head and neck, including cancers of the mouth, pharynx, esophagus and larynx, than non-drinkers.

Research also suggests that even moderate amounts of alcohol can raise women’s risk of breast cancer. "Even just one glass of wine a day can raise a woman's risk of getting breast cancer," Snyder says.

People who habitually indulge in the drink-and-cigarette combo are literally playing with fire, because alcohol works synergistically with smoking to dramatically raise the risk of some cancers.

For example, people who consume an average of more than four drinks per day raise their risk of developing oral and pharyngeal cancer by nine times -- those who are also heavy smokers raise their risk by a whopping 36-fold.

Taking steps to add cancer-fighting foods and reduce risky choices in your diet can pay off handsomely. By some estimates, if more Americans followed the guidelines set by the American Cancer Society to lose excess weight and eat the recommended foods, nearly 195,000 lives would be saved each year.

Wouldn't it be nice if yours or that of a loved one were one of them?

Getting a Fresh Start

A diagnosis of breast or prostate cancer can be quite a jolt, but it also may be the impetus needed to make healthy lifestyle choices that may lead to better health and longer survival. That was the idea behind a Duke study led by former Duke University School of Nursing professor Wendy Demark-Wahnefried, PhD, RD, entitled "Fresh Start."

Sponsored by the National Institute of Health, the study tested the effectiveness of a home-based diet and exercise program that is distributed to participants through the mail.

While "Fresh Start" is no longer recruiting patients, the main results of the paper were published July 1, 2007, in the Journal of Clinical Oncology. The study concluded that mailed material interventions (particularly those that are tailored) are effective in promoting lifestyle changes among breast and prostate cancer survivors.

A new trial called "DAMES" began recruiting in the fall. Demark-Wahnefried and fellow investigators, Snyder, Isaac Lipkus, PhD, Lee Jones, PhD, Gretchen Kimmick, MD, and Bercedis Peterson, PhD, will begin a study that tests the benefits of a weight loss lifestyle intervention in overweight women (over 50 years old) recently diagnosed with breast cancer (within 2 years) and their overweight adult daughters (over 21 years old).

For more information on the DAMES clinical trial, please contact Snyder at DAMES@geri.duke.edu.