January 4,
1997
Many people welcome the New Year with a list of well intentioned resolutions, at least one of which concerns eating habits. The American Cancer Society (ACS) recommends that this year's list include four broad guidelines that, if followed, should lower a person's risk of developing cancer.
Roughly 500,000 people die of cancer each year in the United States. One third of these fatalities can be traced to diet -- a share equivalent to those caused by cigarette smoking, according to a new report by the ACS's Advisory Committee on Diet, Nutrition, and Cancer Prevention, chaired by Marion Nestle of New York University.
Though many people have inherited a genetic susceptibility to certain types of cancer, behavioral factors such as how much we exercise, what we eat, and whether we smoke can all modify the risk of cancer at all stages of its development -- and at any time, from childhood to old age.
"Therefore, for the large majority of Americans who do not smoke cigarettes, dietary choices and physical activity become the most important modifiable determinants of cancer risk," the committee notes in its new guidelines. While acknowledging that no diet offers iron-clad protection against disease, the committee concludes that its recommendations "offer the best nutrition information currently available to help Americans reduce their risk of cancer."
The committee advocates eating fruits or vegetables as a part of every meal and selecting such foods as snacks. Other plant-based foods -- such as breads, cereals, grains, pasta, or beans -- should be eaten several times a day. It says whole-grain products should become a part of each meal, chosen "in preference to processed (refined) grains." Beans can serve as an alternative to meats.
Many studies have linked diets rich in fruits and vegetables to low risks of many cancers, especially those of the gut. How these foods protect remains an open question. As a result, the committee says, "the best advice is to eat 5 or more servings" of fruits and vegetables daily.
What's a serving? You can eat an apple, banana, or orange; a half cup of prepared fruit or cooked vegetables; a 3/4-cup glass of juice; a full cup of raw leafy vegetables; a half-cup of cooked dry beans, cereal, rice, or pasta; a one-third cup portion of nuts; or 2 tablespoons of peanut butter.
Choose lean cuts of meat and keep portions small, at about 2 to 3 ounces. Indeed, the committee recommends using meat as a side dish rather than the focal point of a meal.
Though meats offer high-quality protein and many important nutrients, the committee points out that "consumption of meat -- especially red meats (beef, pork, lamb) -- has been linked to cancers at several sites, most notably colon and prostate."
If you're used to frying meats, consider baking or broiling them -- or replacing them altogether with grains, beans, and produce. Keep in mind that among animal proteins, seafood and poultry generally carry less fat than equivalent-size portions of beef, lamb, and pork.
Substitute skim or low-fat versions for regular milk or dairy products. A standard-size portion of dairy products is 2 ounces of processed cheese or 1 cup of milk or yogurt.
Dietary changes that lower fat intake offer the added benefit of reducing an individual's risk of heart disease.
Try to exercise at least moderately for 30 minutes or more at least 4 days a week. Obesity and sedentary lifestyles have both been linked to heart disease and to cancers at several sites, most notably the colon, rectum, prostate, endometrium (uterine lining), breast (in postmenopausal women), and kidneys.
At present, scientists don't know whether exercise's role in cancer prevention traces primarily to its effect on body weight or through some other factor, such as altering hormone levels or stimulating food's passage through the bowels.
The 30 minutes of exercise does not have to be done all at once to provide benefits, nor must it be painful. An individual can merely walk briskly for about 2 miles, do gardening, swim, or even dance.
Alcoholic beverages cause cancers of the mouth, esophagus, and larynx. The risk goes up with consumption, but the increase can be seen in persons who down as few as two drinks a day. In addition, some studies have reported an apparent link between alcohol consumption and an increased risk of breast malignancies, even among women who average just a few drinks a week. Indeed, the ACS committee says, women who face an especially high risk for breast cancer (owing to family history and other factors) "might reasonably consider abstaining from alcohol."
What constitutes "a drink" varies with the alcohol, for example, it is 12 ounces of regular beer, 5 ounces of wine, and just 1.5 ounces of 80-proof distilled spirits.
The ACS has issued its new 17-page guidelines report in a bimonthly, peer-reviewed journal that it publishes free of charge for health professionals involved in managing cancer care. In addition to fleshing out its basic recommendations, the document also outlines the dietary and activity factors that affect risks of the most common cancers (breast, colorectal, endometrial, lung, oral/esophageal, prostate, and stomach), and includes answers to 31 commonly asked questions about diet and cancer. The topics include consumption of olestra (a fake fat) and phytochemicals and concerns over salt and pesticides.
In an accompanying editorial, ACS president Raymond E. Lenhard, director of community programs at Johns Hopkins Oncology Center in Baltimore, observes that the publication of these dietary guidelines "seems particularly timely in the face of apparent disregard for these principles of good health by many Americans."
He says, "The failure of Americans to adopt a diet that promotes health is reminiscent of the increasing use among teenagers of tobacco." Moreover, Lenhard notes, many institutions that should know better appear to be subverting related dietary warnings that have been issued by ACS and a host of government agencies.
He notes, for instance, that ACS's efforts to educate young people "swims against the tide of high-fat, low-cost foods made available to the nation's school lunch programs." One such food is pizza. Not surprisingly, he observes, "Surveys of eating habits of school children confirm that pizza, the antithesis of the guidelines listed in this report, is the single most popular food choice."
References:
Lenhard, R.E. 1996. American Cancer Society Nutrition Guidelines. CA -- A Cancer Journal for Clinicians 46(November/December):323.
Nestle, M., et al. 1996. Guidelines on diet, nutrition, and cancer prevention: Reducing the risk of cancer with healthy food choices and physical activity. CA -- A Cancer Journal for Clinicians 46(November/December):325.
Related Readings:
Fackelmann, K.A. 1994. Veggies may cut nonsmoker lung cancer risk. Science News 145(Jan. 8):23.
_____. 1993. Refiguring the odds: What's a woman's real chance of suffering breast cancer? Science News 144(July 31):76.
_____. 1993. Cancer protection from fruits and veggies. Science News 143(June 5):358.
Kristal, A., R. Patterson, et al. 1995. Psychosocial correlates of healthful diets and intention to improve diet: baseline results from the Working Well Study. Preventive Medicine 24:221.
Lipkin, R. 1995. Vegemania: Scientists tout the health benefits of saponins. Science News 148(Dec. 9):392.
Raloff, J. 1996. Overeating: Understanding bad habits. Science News Online (Dec. 7).
_____. 1996.Veggies may offer strong defense against breast cancer. Science News Online (July 20).
Sources:
American Cancer Society
1599 Clifton Road, N.E.
Atlanta, GA 300329
Phone: 1-800-ACS-3245
WEB: http://www.cancer.org
This week's Food for Thought is prepared by Janet Raloff, senior editor of Science News.
Illustration: Wendy Temple.
Food for Thought Archives! 
