 For Cancer Survivors
Frequently Asked Questions (Updated July 2007)
Knowledge is your best defense against a secondary tumor or recurrence of cancer. Below are some of the most common questions about diet and exercise that cancer survivors ask after treatment. The answers are based on current research.
Why am I so tired? What can I eat to boost my energy?
Fatigue is common among cancer survivors after treatment, but it may not be related to nutrition. You should discuss the problem with your physician. In the meantime, you should eat for good health. A mostly plant-based diet that includes enough calories to support a healthy weight and meet any increased nutritional requirements is ideal. Protein (animal or plant) or whole grains tend to provide more sustained energy than refined carbohydrates.
You should also drink plenty of fluids. Dehydration worsens fatigue. Make sure you drink at least 8 cups a day. If you are gaining too much weight, drink mostly water; if you are unintentionally losing weight, include some calorie-providing fluids such as milk or juice.
Exercise, especially a light to moderate walking program, can also help increase your energy and improve your sense of well-being. Your physician can offer guidance concerning when to start physical activity and how much activity is right for you.
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I am still having trouble digesting food since my treatment. Is there something besides the high-calorie nutritional supplement drinks that I can eat?
Food tolerance is an individual issue. Some cancer survivors will have trouble with gastrointestinal symptoms, such as nausea, diarrhea, constipation, swallowing and bloating, while others may not. Nutritional beverages may be of help to you. Eliminating milk and milk products may be helpful for people who have developed lactose intolerance. Others may have difficulty tolerating high-fiber foods, such as whole-grain breads and cereals.
A counseling session with your oncologist, oncological nurse or a registered dietitian may help you figure out what foods to try and which ones are more likely to upset your stomach. You may find that keeping a diary of what you eat and how you feel will help you determine what to avoid. Adding back one food at a time can also help you decide what you are best able to tolerate.
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Should I take supplements?
 If you are still undergoing cancer treatment, you should discuss supplementation with your physician. Some dietary supplements may be detrimental to some types of treatment.
If you have completed cancer therapy, it is important to know that supplements cannot take the place of a varied and healthful diet. Getting adequate calories from a variety of healthful foods to satisfy your nutrient requirements is most important. Many individuals can benefit from adding a “one-a-day vitamin pill” that offers a 100 percent Daily Value (DV) of vitamins and minerals. But you cannot obtain the protective benefits linked to eating a wide variety of vegetables and fruits from pills. Researchers have not yet identified all the protective phytochemicals in fruits and vegetables, and studies suggest that phytochemicals in foods work together to provide benefits. In addition, a balanced diet provides fiber, protein and essential fatty acids necessary for health.
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Should I switch to a lowfat diet?
Although dietary fat was once considered a major factor in cancer risk, recent research has shifted focus to emphasize the cancer-protective effect of vegetables and fruits. For better general health, you should avoid excessive amounts of fat, especially saturated fat, which is found in fatty meat and high-fat cheese, milk and ice cream. But some fat is needed in your diet. Moderate amounts of olive and canola oils, nuts and fatty fish are good choices.
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Should I become a vegetarian?
Research shows that the most important dietary change you can make is to eat a mostly plant-based diet. It does not appear that vegetarian diets are any more protective than other mostly plant-based regimens. Therefore, you do not have to eliminate all animal-based foods from your meals. AICR recommends that you fill your plate with two-thirds (or more) vegetables, fruits, whole grains and beans and one-third (or less) fish, poultry or meat.
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Will soy protect me from breast cancer? Or is it harmful?
 There is no sound evidence at this time that soy will benefit breast cancer survivors. There is evidence that soy offers some protection against breast cancer for women who began eating soy at an early age. Yet several recent laboratory studies suggest that soy could increase breast cancer risk for some women. If you enjoy soy foods, current research supports the safety of including moderate amounts of soy foods (e.g., soymilk, tofu) as a part of a mostly plant-based diet, up to two to three servings per day. Supplements of soy protein or isoflavones are not adequately researched at this time and, therefore, not recommended.
Current recommendations advise women taking tamoxifen or aromatase inhibitor medicines to avoid or strongly limit soy foods until treatment is concluded. Women who have had estrogen-positive (ER+) breast cancer may want to be somewhat restrictive in their soy intake (perhaps no more than a few servings of soy per week) until research provides clearer answers.
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Should I eat flaxseed?
More research on flaxseed is needed to make a specific recommendation. In laboratory studies, flaxseed has shown anticancer properties, but a few studies have found high amounts of flaxseed may contribute to cancer development. For now, a small amount of ground flaxseed (1 tablespoon) per day may provide some health benefits and is most likely safe. Until more information is available, women undergoing breast cancer treatment, children, and women who are pregnant, breast feeding, or trying to conceive should not consume flaxseed.
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How can I gain weight back that I lost during treatment?
Eat several small mini-meals throughout the day if you find you can’t eat much at one time. Choose foods that are concentrated in calories and nutrients, such as dried fruits, nuts, bean dips or spreads; fruit dipped in peanut butter; whole-grain crackers with reduced-fat cheese; high-calorie cereals; juice; and nutritional supplement drinks. These foods will help you increase your calorie consumption to gain weight back gradually.
Talk to your oncologist, oncological nurse, or dietitian at your cancer center. These health professionals should be able to identify individualized strategies for weight gain.
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How can I lose weight?
It is not unusual for some cancer patients to gain weight after diagnosis and during treatment. This can happen for several reasons. Any attempt to lose weight, however, should be done slowly and carefully to ensure that you will be getting all the nutrients you need. Emphasizing plant-based foods in the diet, including vegetables, fruits, whole grains and beans can help. These foods are low in calories and fat, while high in nutritional value.
Make sure that your portion sizes are appropriate, too. Especially if your activity level has dropped or you have gained weight, try eating smaller portions to see if your hunger is satisfied with less. Address depression, stress and boredom in ways that don’t involve eating. Sleep rather than eat when tired. Even a little physical activity can make a big difference, so follow your physician’s advice about when and how you can be active.
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I am a prostate cancer survivor. Should I still eat dairy products?
At this time, high use of dairy products providing calcium beyond 1,500 mg a day has been linked to a possible increase in prostate cancer. But including two servings of dairy products daily as part of a balanced diet will keep calcium safely below that level. Low-fat and non-fat dairy products like milk and yogurt provide a variety of important nutrients.
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Does sugar promote cancer? Should I avoid it?
Sugar in itself does not promote cancer. Consuming small amounts of sugar as part of an overall healthful diet is fine, but large amounts of sugar may indirectly raise cancer risk in two ways. Diets high in sugar can lead to elevated levels of blood sugar, which can raise insulin levels. Routinely high levels of insulin may, in turn, raise the risk of colon cancer, and perhaps other cancers. This indirect chain of events is seen most commonly among people who are overweight and sedentary or those who have insulin resistance or diabetes in the family.
Another way high sugar consumption may increase cancer risk is by leading to weight gain. Lots of sugar equals lots of calories which, over time, equals excess weight. And excess weight is linked to greater risk of several types of cancers.
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Which fruits and vegetables should I be eating?
Eat as many different vegetables and fruits as you can. Variety is the key to obtaining the numerous protective phytochemicals in plant-based foods because each vegetable and fruit has its own profile of health-promoting substances. The phytochemicals found in cantaloupe are different from those in broccoli or leeks or cherries. Try to eat some bright red, green, orange, blue, purple and yellow vegetables and fruits each day.
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Should I buy organic foods whenever possible?
When it comes to cancer risk, there is no convincing evidence showing a difference between organic and conventionally grown foods. Market studies show pesticide residues on conventionally grown foods are almost always within safety tolerance limits. If you are concerned about pesticide residues and can afford to spend more, organic produce may be a choice for you as long as the higher cost will not lead you to cut back on eating fruits and vegetables. However, for beater health eat generous servings of a large variety of veggies and fruits -- whether organic or not. The benefits of eating more vegetables and fruits strongly outweigh any potential risks from pesticides.
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