Guidelines Created to Help Prevent Cancer
CancerWise - April 2008
By Dawn Dorsey
Health experts are recommending new ways to help prevent cancer based on scientific evidence that choices about diet, physical activity and weight play a major part in a person's chances of developing the disease.
The report contains new health guidelines based on the analysis of more than 7,000 scientific studies by 21 international experts over more than five years. The document was released by the American Institute of Cancer Research (AICR) at its annual meeting in November and has been used since then as a guide in
M. D. Anderson's Cancer Prevention Center.
“This is the most comprehensive research to date about cancer prevention and nutrition,” says registered dietitian Sally Scroggs, manager of health education in the Cancer Prevention Center.
The recommendations focus on three main guidelines:
- Choose healthy foods:
- Eat mostly plant foods
- Limit red meat and avoid processed meats
- Be physically active every day for at least 30 minutes
- Maintain a healthy weight throughout life
Re-examine your plate
A way to translate the dietary recommendations to daily life is to make sure at least two-thirds of your plate consists of plant foods, Scroggs says.
Plant foods include:
- Antioxidant-rich fruits and vegetables
- Legumes (beans)
- Whole grains
Fruits and non-starchy vegetables (carrots, broccoli) help protect against cancers of the mouth, pharynx, larynx, esophagus, stomach, colon, rectum, liver, pancreas, ovary, endometrium and lung.
Red meat should be treated like more of a small side dish, Scroggs says. According to the AICR report, people should closely limit red meat (beef, pork and lamb) to 18 ounces or less each week. Alternatives include fish and poultry.
“We talk to our patients about their red meat consumption,” Scroggs says. “And we tell them there is new, more-substantiated evidence that limiting red meat helps prevent several types of cancer, especially colorectal cancer.”
Scroggs is quick to point out to patients, however, that the guidelines do not prohibit meat. Meat can be a valuable source of essential nutrients such as protein, iron, zinc and vitamin B12.
“It all boils down to portion size, which is something Americans need to be more conscious of in their diets,” Scroggs says. “A piece of meat, say 3 ounces or so (the size of a deck of cards), is OK several times a week.”
However, the report cautions people to avoid all processed meats, including hot dogs, lunch meats and ham.
What’s so bad about meat?
Scroggs says researchers used to think the saturated fat in meat increased the chance of cancer, but current research points to a number of other reasons. Studies have shown, for instance, that red meat consumption increases the production of carcinogens in the colon. Cooking at high temperatures also produces additional carcinogens.
Processed meats, which are preserved by salting, smoking, curing or treating with chemicals, have been found to increase cancer risk. Researchers are studying exactly what causes this to happen.
The same cancer-causing factors in red meat may be responsible, or it may have to do with the chemicals that are used for processing. Researchers do know that carcinogens, specifically N-nitroso compounds, are produced when meat is processed.
Be active daily
Physical activity is particularly valuable in preventing breast, endometrial and colorectal cancers.
The researchers recommend people try activities they enjoy.
They also suggest:
- Exercising moderately every day for 30 minutes
- Limiting sedentary activities (watching television)
As fitness improves, aim for at least 60 minutes of moderate activity or 30 minutes of vigorous activity every day.
Watch your weight
The single most important way to avoid cancer is to maintain a healthy weight throughout life.
The most common method of measuring body fat is calculating your body mass index. (BMI can be calculated through the National Institutes of Health Web site.)
The report also looks at body fat distribution (measured by waist circumference and waist to hip ratio) and patterns of weight gain. There is evidence that abdominal fat, in particular, is linked to colorectal, pancreatic, postmenopausal breast and endometrial cancers.
“Of course, these components all work together,” Scroggs says. “Eating a healthy diet and getting the recommended amount of physical activity will help you maintain a good weight. Also, following this regimen will help fight against other chronic diseases, such as diabetes and heart disease.”