The World Cancer Research Fund, together with the American Institute for Cancer Research (AICR) issued the report “Food, Nutrition and the Prevention of Cancer” describing the impact of nutrition and exercise on the prevention of cancer. We asked Lauren Talbert, RD, CSO, LDN, of the Program in Women’s Oncology at Women & Infants to talk about the report.
In the report, more than 7,000 studies related to food, nutrition and cancer were reviewed by 21 world-renowned experts including world-famous scientists, researchers, and physicians. The goal was to review all the relevant research, using the most thorough methods, in order to generate a comprehensive series of recommendations on food, nutrition, and physical activity.
10 recommendations to reduce your risk of cancer?
- Be as lean as possible without becoming underweight.
- Be physically active for at least 30 minutes every day.
- Avoid sugary drinks.
- Limit consumption of energy-dense foods (particularly processed foods high in added sugar, low in fiber, or high in fat).
- Eat more of a variety of vegetables, fruits, whole grains and legumes (such as beans).
- Limit consumption of red meats (beef, pork, and lamb) and avoid processed meats.
- Limit alcoholic drinks to two a day for men and one for women, if at all.
- Limit consumption of salty foods and foods processed with salt (sodium).
- Don’t use supplements to protect against cancer.
- It is best for mothers to breastfeed exclusively for up to six months and then add other liquids and foods.
- After treatment, cancer survivors should follow the recommendations for cancer prevention.
- Do not smoke or chew tobacco.
There’s been increased mention of “energy-dense” foods. What are they?
One of the 10 recommendations is to limit energy-dense foods and avoid sugary beverages. Energy density measures the amount of energy (calories) per weight of food. Processed foods such as cookies, chips, fried foods, and desserts are examples of energy-dense foods. These foods often contain large amounts of fat or added sugar and tend to be more “energy-dense” than fresh foods such as fruits or vegetables. For example, half a cup of Ben and Jerry’s Coffee Health Bar Crunch ice cream contains 290 calories, 27 grams of sugar and 18 grams of fat. This is clearly an example of an energy-dense food when compared to half a cup of sliced fresh strawberries that contains 27 calories, 4 grams of sugar and 0.2 grams of fat. The best way to limit energy-dense foods is to increase the proportions of plant foods (fruits, vegetables, whole grains and beans) in your diet. You should also avoid sugary drinks. Because of their water content, drinks are less energy-dense than foods. Sugary drinks provide “extra” calories to the diet and consuming more calories than required causes weight gain.
The report urges people not to use supplements to protect against cancer. What sort of supplements do they mean?
Dietary supplements are also known as vitamins. Evidence from the reviewed studies showed that high-dose nutrient supplements, for example taking a Vitamin C pill daily, can be either protective against cancer or cause cancer. The problem is that the studies are conflicting and the balance of risks and benefits cannot confidently be predicted in the general population. It’s always best to consume nutrients from their natural state, in fresh foods, rather than in a processed form. Instead of taking a Vitamin C pill, eat an orange.
You have boiled these 10 recommendations down to something that is more realistic, with three goals. What are they and why have you chosen to focus on them?
AICR’s recommendations for cancer prevention have been simplified into three guidelines. These guidelines explain how the choices we make about food, physical activity, and weight management can reduce our chances of developing cancer. The three guidelines are closely related to each other:
- Choose mostly plant-based foods, limit red meat and avoid processed meat.
- Be physically active every day for 30 minutes or more.
- Aim to be a healthy weight throughout life.
It is easier to understand and follow three goals rather than 10 recommendations. The three goals were created as realistic guidelines you can think about and gradually adopt when making everyday choices related to diet and exercise. Following any one of these guidelines is likely to reduce your chance of getting cancer, but following all three offers the greatest protection.
You’ve actually diagrammed the whole grain into three parts to show its nutritional value. Can you describe those parts and their value?
A whole grain is the entire edible part of any grain. It contains the bran, endosperm, and germ. The bran is the outer layer of the grain and is often high in B vitamins and fiber. As you may recall, bran cereal is known for being high in fiber. The endosperm is the inner part of the grain that contains most of the carbohydrate. There is a small amount of vitamins and minerals in the endosperm. The germ provides nourishment to the seed. It’s rich in antioxidants, Vitamin E, fiber and B vitamins.
What happens when the whole grains are refined? How can people be sure they are getting the best type of grain for their nutritional needs?
When grains are refined, the bran and the germ are removed resulting in a depletion of many nutritious compounds. It’s always best to choose whole grains to increase your intake of fiber and nutrients that may lower cancer risk. When reading labels, be sure to choose foods that list whole or whole grain before the grains name as the first ingredient. Do not rely on color to identify a whole grain as ingredients such as molasses or caramel coloring may have been used during processing. The following terms do not necessarily indicated a whole grain either:
- Wheat flour.
- Stone ground.
- 100 percent wheat.
- Seven grain.
Examples of whole grains include:
- Brown rice.
- 100 percent whole wheat bread.
- Whole wheat pasta.
- Bran cereal.
There is evidence connecting red meat to increased risk of colorectal cancer. Should people become vegetarian or vegan?
There is convincing evidence that red meat (beef, lamb and pork) increases the risk of developing colorectal cancer. Also, most vegetables and fruit are rich in fiber, and fiber probably protects against colorectal cancer. Furthermore, evidence shows that eating more vegetables and fruits probably protects against cancer of the mouth, pharynx, larynx, esophagus and stomach. A typical American meal features red meat, such as an 8-ounce steak with mashed potatoes or a cheeseburger with fries. The recommendation to limit red meat helps leave more room for plant-based foods such as vegetables, fruits, whole grains and beans to be included in the diet. If you do consume red meat, it’s recommended that you limit consumption to 11 ounces, or roughly two servings, a week. Red meat is generally high in calories and fat so choose lean cuts to help control calorie intake. In terms of cancer risk, people do not need to become vegetarian or vegan as no evidence connects fish or poultry to increased cancer risk. In fact, poultry and fish can be a valuable source of nutrients, particularly protein, iron, zinc, and Vitamin B12.
What about processed meat?
Processed meat is defined as meat that is preserved by smoking, curing, salting or adding other chemical preservatives. Examples include:
- Lunch meats.
- Hot dogs.
Similar to red meat, evidence is convincing that processed meats can increase your risk of colorectal cancer; however, the risk is considerably greater. If you are concerned with avoiding colorectal cancer and stomach cancer, it’s best to try to eliminate processed meat from your diet. For lunch, try a tuna sandwich or buy lunch meat that contains no nitrates or nitrites. Also, try to look at processed meats as something you save for a special occasion, maybe ham at a holiday meal or a hot dog at a baseball game. Once you start to include more plant-based foods in your diet, it will be easier to avoid foods such as red meat and processed meat.
What are your suggestions for meal planning?
When planning a meal, think first about plant-based foods. Visualize your breakfast plate, for example, and aim to cover one-third with a whole grain, one-third with a fruit, and one-third with a protein. An example could be eggs with 100 percent whole wheat toast and an orange or 100 percent whole grain cereal with milk and fresh berries. A good rule of thumb for your lunch or dinner plate is cover half of it with vegetables, one-quarter with whole grains or beans and one-quarter with lean protein such as poultry or fish. An example for a dinner could be a chicken and vegetable stir-fry over brown rice with a side salad. Ask yourself these questions: What vegetables or fruits will I include? How can I incorporate a whole grain or beans into the meal? If you are looking for a recipe, check out aicr.org for some tasty ideas.
You note that as Americans have become more sedentary, cancer rates have increased. Is there a proven relationship here? Are there known benefits of exercise with cancer risk?
In early hunter-gathering societies, physical activity was necessary for survival. Today, if we are hungry, we have drive-thru fast food restaurants and vending machines. More people are spending their leisure time sitting in front of computer or television screens instead of being active. Cancer rates have increased as the population has become more sedentary. Research has proven that regular physical activity protects against cancer. It’s important to make sure it’s part of your daily routine just like brushing your teeth. Sometimes we may be too tired at night to brush but we do it anyway because we want to avoid cavities. The same goes for exercise. Sometimes you may not feel like doing it, but the benefits both physically and mentally are well worth it. Research has shown that physical activity protects against colon cancer, post-menopausal breast cancer and cancer of the uterine lining (endometrium).
What’s interesting is that regular exercise reduces cancer risk alone, not including reduced risk with weight loss that is often seen with exercise. You may wonder how exercise decreases the risk of certain cancers. In terms of breast and endometrium cancer, exercise may prevent cancer by lowering the levels of hormones in the body that elevate cancer risk. Regular exercise keeps your digestive system working well and more rapid passage of waste through the colon may be associated with lower incidence of colorectal cancer.
What types of cancer are affected by higher BMI?
BMI or body mass index is one tool used to measure body fat. It measures weight in relation to height. To calculate your own BMI, go to aicr.org/bmi. There are four ranges of BMI:
- Underweight is less than 18.5.
- Normal weight is 18.5-24.9.
- Overweight is 25-29.9.
- Obese is 30 or greater.
Does any type of physical activity help?
Of course. Physical activity is any form of movement that uses muscles. Basically you are physically active any time you are not sitting or laying down. Each day, we make several choices related to physical activity:
- Elevator or stairs.
- Park close or far away.
- Walk my dog or let it out in the backyard.
The more physically active you are the better. There are three terms used to describe the intensity of physical activity: light, moderate and vigorous. An example of light exercise is weeding the garden. Leisurely cycling would fall into the moderate category. Running at 10-minute mile would be considered a vigorous level of intensity.
What about the people who say they are too tired, too busy, too broke or too out of shape to exercise?
The good thing about exercise is that it actually increases energy levels, doesn’t have to be expensive, it’s never too late to start and everyone can do it at their own pace. Just as regular physical activity reduces the risk of cancer, the opposite is true also. These people may want to ask themselves if they are too tired, too busy, too broke or too out of shape to enjoy a longer life? Research does show that people who are more active live longer. Exercising can be as simple as waking up a few minutes early and going for a walk or meeting a friend for a walk instead of lunch. It’s important to first identify your barrier and develop a strategy to overcome the barrier. “If you can find a path with no obstacles, it probably doesn’t lead to anywhere.” A great inexpensive way to increase physical activity is to purchase a pedometer and track your daily steps. This way, you can quantify your goals such as aiming to walk 5,000 or 10,000 (the recommended amount) steps a day. The bottom line is if you truly want to increase your activity level, you can. The key is to find something that you find enjoyable and that you look at as fun rather than a chore. Maybe dance lessons or learning a new sport may be in your future.