No single food or nutrient will remove the risk of cancer, but following some guidelines can reduce your chances of developing certain types of cancer. (As an added benefit, some of these guidelines also help prevent heart disease, obesity and diabetes.) And for those who already have health problems, making these dietary changes can give you the needed stamina to fight the disease, plus increase your immune response and make treatment more tolerable. To help you remember these guidelines in your everyday food choices, think P-R-E-V-E-N-T.
Many experts believe that adding more plant-based foods is the dietary cornerstone to prevent many types of cancer. That's because fruits, vegetables and other plant-based foods typically are:
- Low in saturated fats, the animal fats found in meats, butter and cheese that are linked to an increased risk of cancer, heart disease and other diseases
- The best sources of phtyochemicals, natural substances in fruits and vegetables that seem to offer some protection against the formation of certain types of tumors
By eating mostly plant-based foods, you will more easily reach the dietary goal of eating 6 to 11 servings of breads, grains, and cereals; 2 to 4 servings of fruit; and 3 to 5 servings of vegetables. In fact, the goal of "Eat 5 to 9 A Day" — or 5 to 9 servings of fruits and vegetables each day — is the cornerstone of the National Cancer Institute's dietary guidelines for cancer prevention. One recent NCI report stated that if everyone followed the "Eat 5 to 9 A Day" guideline, cancer incidence rates could decline by 20% or more. To learn more about the "Eat 5 to 9 A Day" program, including tips and recipes, go to www.5aday.gov.
A diet rich in whole-grain foods and other forms of fiber, rather than simple or refined carbohydrates, will help to avoid the obesity that may increase the risk of cancer. Fibers make up the structural parts of plants and therefore are found in all plant-based foods — including fruits, vegetables, grains, breads and cereals. They are not found in meat, milk, cheese or oils. The refining process used to make white flour removes almost all of the fiber from grains.
By definition, fiber is resistant to digestion, so its effects are mainly what it does as it passes through the body. There are many different types of fiber with different effects in the body, but they are generally classified into two groups: soluble and insoluble.
Soluble fibers are those that can dissolve in water. They typically are in highest amounts in fruits, legumes, barley and oats. They generally slow down digestion time, allowing you to feel full longer and allowing your system plenty of time to absorb nutrients from the foods you eat. More significantly, soluble fibers bind with bile acids in your intestines and carry them out of your body. Since bile acids are made from cholesterol, soluble fiber can lower your cholesterol levels.
Insoluble fibers are the type found in vegetables, whole-grain breads and whole-grain cereals. They increase the bulk of stool, help to prevent constipation and aid the removal of bound bile acids from your system. Insoluble fiber also increases transit time, or the speed that food moves through your gastrointestinal system.
Both types of fiber are important for good health and cancer prevention, and you can get them by eating a varied plant-based diet. Ideally, everyone should get at least 25 grams of fiber each day — about twice the amount most Americans currently consume. A good way to achieve that amount is to eat the NCI's recommended five fruits and vegetables each day. You can boost your fiber intake by eating the skins of potatoes and fruits such as apples and pears, since the skins contain a lot of fiber. Switching from refined foods to whole-grain foods also is advisable. That means choosing whole-wheat breads over white and brown rice over white. Other good sources of fiber include legumes, lentils and whole-grain cereals.
If a diet lower in saturated fat keeps weight under control, it may help decrease the risk of developing cancer of the prostate, endometrium and breast.
The three types of dietary fats — saturated, monounsaturated and polyunsaturated fats — differ in their molecular structure: Saturated fats come almost exclusively from animal products, such as meat, milk and cheese. A diet high in saturated fats has been associated with increased risk of both cancer and heart disease. Monounsaturated fats, found in olive oil and canola oil, and polyunsaturated fats, found in vegetable oils, are now considered healthy fats as long as they are used in moderation so that total calories consumed does not increase body weight.
Trans fatty acids are especially unhealthy. Trans fats do not occur naturally. They are produced by a chemical process called partial hydrogenation that changes the consistency of vegetable oil from liquid to solid or semi-solid. Trans fatty acids are abundant in stick margarine. They are used in most restaurants for deep frying foods such as French fries. Although no firm association with cancer has been found, recent studies suggest that trans fats are even worse for the heart than saturated fats.
The usual recommendation is that you should get no more than 10% of your daily calories from saturated fats. The remainder of calories should come primarily from whole-grain foods, vegetables, fruits, nuts and healthy protein sources like fish, beans and soy.
Try to eat a variety of foods, especially vegetables and fruits. Fruits and vegetables are natural sources of vitamins, minerals and antioxidants. Research continues to show that foods containing these ingredients are much better than supplements at lowering blood pressure, preventing heart disease and decreasing cancer risk.
Antioxidants are substances that seek out and destroy the naturally occurring toxic molecules called free radicals. Free radicals can cause extensive damage to the body's cells. The damage done by free radicals is called oxidative stress, which is thought to be involved in cancer development. Antioxidants reduce the number of free radicals, prevent tissue damage and, quite possibly, prevent cancer.
What does exercise have to do with nutrition? Plenty. Exercise helps the body function properly so that all the food you eat gets used optimally. Also, exercise builds lean muscle and burns calories. Exercise even without weight loss has been associated with a lower risk of colon and breast cancer. If you are also avoiding obesity, you also decrease your chance of developing cancer of the breast, colon, prostate and uterus.
You don't have to run marathons or buy a basement full of expensive equipment to improve your health through exercise. Recent guidelines suggest doing 30 to 45 minutes of any kind of activity every day. And you don't have to do all 30 minutes at one time — taking a 10-minute walk around the block in the morning, mowing the lawn after work and playing with the dog in the evening will be enough to satisfy the requirement. There's no trick — you just have to move, since exercise also speeds up transit time, which may reduce your risk of colon cancers. The more you do, the greater the health rewards. Just remember to start slowly, and see your doctor before starting any vigorous exercise program.
Whenever possible, choose foods that come as close to their natural state as possible. That means selecting whole-wheat bread over refined flour breads, fresh fruits and vegetables over canned, whole-grain cereals over cereals that are heavily sugared, and brown rice over white rice.
If you smoke or use any tobacco products, stop. The single greatest cause or correlate of cancer is smoking — and this goes beyond lung cancer. Smoking is directly related to mouth and esophageal cancers and has been shown to cause an increase in risk of cancers of the pancreas, stomach and bladder. Chewing tobacco, far from being a safe alternative, is associated with an increased risk of cancers of the mouth and throat. Smoking can also decrease appetite, so you may not get all the nutrients you need.
In addition, alcohol should be limited to no more than one 1-ounce drink a day for women and two drinks a day for men. Alcohol has also been associated with cancers of the breast, liver, esophagus, mouth and throat.