The Diet-Cancer Connection.
The medical profession has come a long way since Hippocrates first said, "Let food be thy medicine and medicine be thy food. Perhaps it's time to take a few steps back. A full third of the 563,000 cancer deaths the American Cancer Society predicts for 1999 will be nutrition-related. In fact, dietary choices are linked to 70 percent of all diseases affecting Americans, yet only 30 of 125 U.S. medical schools require doctors to take a nutrition course. In four years of school, the average physician gets only 2.5 hours of nutritional training.
If the food and health connection were better known, more people might be aware that maitake and shiitake mushrooms stimulate immune function; that selenium, a mineral found in grains, and garlic, induces cancer cell death; that antioxidants in turmeric, an herb in curry powder, prevent DNA damage and block tumor growth; or that there is actually twice as much calcium, which protects against osteoporosis and colon cancer, in a cup of spinach as a cup of milk.
Academia is digging deep into the powerful efficacy of everyday foods like broccoli, mint, even honey. The American Institute of Cancer Research (AICR) recently reviewed over 4,500 such studies and filtered them into a single comprehensive report, "Food, Nutrition and the Prevention of Cancer: A Global Perspective." The bottom line? "Cancer is a preventable disease."
Back to Basics
While advice on individual food choices and herbal supplementation abounds, the numbers still boil down to one fact: Eating five servings of fruits and vegetables a day may prevent well over 20 percent of all cancer cases, including those of the colon, stomach, lung, esophagus, breast, bladder, pancreas and prostate. "Unfortunately, we live in a society where one in three people will hear the words `you have cancer;" says Dr. Mitchell Gaynor, director of medical oncology at the Strang Cancer Prevention Center. "But the good news is that cancer is usually the result of a decades-long process and nutrition is a way of thwarting each step."
Some of the most powerful cancer-fighters are antioxidants which stabilize free radicals (highly-reactive oxygen molecules) and halt cellular damage. Vitamin C, an antioxidant in citrus fruits and strawberries, also raises the activity of "natural killer cells," which search for roaming cancer. Vitamin E, in leafy greens and nuts, may protect against genetic defects that increase cancer risk. And beta-carotene, in carrots and sweet potatoes, may block the formation of tumors.
Likewise, phytochemicals, which give plants their flavor, aroma and pigment, have many roles in potentially preventing cancer growth. They block hormonal actions and metabolic pathways associated with cancer evolution, stimulate enzymes that flush out carcinogens and suppress the growth and division of cancer cells. And lycopene, a phytochemical found in tomatoes and red grapefruit, is actually twice as powerful as beta-carotene at eliminating free radicals.
Legumes such as lentils and black beans provide a significant amount of protein and fiber, and harbor valuable vitamins and phytochemicals. Soy products like tofu and tempeh have stormed the nutritional scene with their ability to inhibit hormone-dependent cancers and reduce the development of blood vessels that feed tumors.
Whole grains--the staples of civilizations for centuries--provide a valuable source of fiber, phytochemicals and antioxidants, which the refining process, unfortunately, removes. Refined wheat, for instance, loses 83 percent of its nutrient value. On the other hand, organically-grown foods have double the mineral content of those grown conventionally. They're also free from pesticides, ranked the number three cancer risk by the Environmental Protection Agency (EPA).
"Humans put two to three pounds of food into their bodies every day" says Linda Koo, an epidemiologist with the American Health Foundation. And they also take in six or seven different pesticide residues from the more than 20,000 manufactured annually. Food, Koo adds, "is our greatest contact with the environment.
Hard to Stomach
Evidence indicates that what you don't eat may be as important as what you do. The National Research Council points to fat and calorie overconsumption as the principal dietary cause of cancer. The current Recommended Daily Allowance (RDA) for fat calories is 30 percent, a guideline Dr. Joseph Keon, author of The Truth About Breast Cancer, says "absolutely no scientific evidence exists to support ... For real protection, dietary fat intake needs to be reduced to 20 percent of calories or less." But most Americans don't even come close to that. According to the Department of Agriculture, one-third of adults and one-fifth of adolescents in the U.S. are overweight, and the rate has increased across all race and sex groups since the 1970s.
"The Third Report on Nutritional Monitoring in the U.S." indicates that between 1980 and 1992, the amount of money spent per person in urban households doubled for frozen, prepared foods; spending on potato chips, nuts and snack foods increased 60 percent; carbonated drinks rose 21 percent. Manufactured and packaged using fossil fuels, the sugar, salt and fat in highly-processed items may displace all but seven percent of the real food. Meanwhile, sugar produces faster-growing and more deadly tumors in animal tests, while dietary fat may alter sex hormone levels, immune responses, cell membrane function and metastasis. They both increase the body's vitamin requirements. This helps explain why countries with high-fat, meat-based diets consistently show higher incidence and mortality rates for breast, prostate and colon cancers.
High in saturated fats, meat products are problematic for several reasons. Meat lacks fiber--which controls weight, stimulates immune function and maintains hormonal balance--but it also provides excess iron, which produces free radicals and lowers immunity. Even organic, lean cuts are devoid of antioxidants and are low in vitamins and minerals. Meat also accumulates pesticide residues, drugs and other chemicals. Humans now carry dioxin levels in their bodies hundreds of times greater than the "acceptable" cancer risk as defined by the EPA, and 95 percent of that results from eating red meat, fish and dairy products. An Earth Save study of 11,000 people showed that those on a vegetarian diet have a 40 percent lower risk of developing cancer than meat-eaters.
Food for Thought
Despite a growing body of scientific evidence, the call to nutritional arms has not been received without protest. The American Council on Science and Health (ACSH) published a particularly harsh critique of Dr. Bob Arnot's controversial book The Breast Cancer Prevention Diet, which illustrates how to incorporate dietary and lifestyle changes to ward off cancer. The ACSH, a self-proclaimed consumer education group funded by food and chemical companies, accurately warned, "Following the book's advice could result in substantial disruption of eating patterns." But when the average American's diet includes consuming 37 percent of daily calories as fat, four times the minimum daily protein requirement and 140 pounds of sugar a year, is that so bad?
The AICR found that appropriate diets alone may prevent three to four million cancer cases a year worldwide. But "it's not a matter of what disease you don't want to get," says Melanie Polk, AICR director of nutrition education. The same lifestyle changes also lower the risk of heart disease, diabetes and high blood pressure, and improve overall health. "We used to think there isn't much we can do, but now we know the way we live does make a difference." CONTACT: American Institute for Cancer Research, 1759 R Street NW, Washington, DC 20009/(800)843-8114; American Cancer Society, 1599 Clifton Road NE, Atlanta, GA 30329/(404)320-3333.
JENNIFER BOGO is E's editorial assistant.
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|Date:||May 1, 1999|
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