Download Breast Cancer FAQs

Breast Cancer and Nutrition
Frequently Asked Questions
1. Is it safe to take vitamin or herbal supplements while getting chemotherapy or
radiation?
There are actually several studies that show potential interactions between antioxidant vitamin supplementation
(Vitamins C, E, and A for example) and cancer treatments, both radiation and chemotherapy. The theory is that
since antioxidants protect the body's cells from oxidation or damage, that taking excess amounts of them may
protect the cancerous cells from oxidative cancer treatments, therefore decreasing the effectiveness of the
treatments. There have also been some studies showing benefit from combining antioxidants and chemotherapy.
Since research is not yet conclusive in this area, it is usually recommended that patients avoid extra antioxidant
vitamin supplements through out treatment. Herbal supplements should also be avoided since they often contain
high levels of antioxidants and can interact with cancer treatment. A standard multivitamin that provides 100% of
the RDI for vitamins and minerals is okay.
2. Is there a special diet that I should follow while undergoing chemotherapy or
radiation treatment?
While undergoing cancer treatment, it is wise to focus on following a healthy diet that will nourish your body
during treatment. Make sure that you get enough protein (about 1/2 gm per pound of body weight ) from lean
protein foods (fish, chicken, low fat dairy foods and legumes), emphasize the "healthier" fats (the monounsaturated
and omega 3 fatty acids), eat whole grain foods, as well as lots of fruits and vegetables, and drink plenty of water
and or other decaffeinated fluids. Sometimes the side effects of treatment may make it difficult to follow a
"perfect" diet all the time. When one’s appetite is affected or nausea develops it is important to eat the foods that
work for you during those times. Refer to the “Nutrition During Breast Cancer Treatment” section of this brochure
for further information on handling the side effects of treatment. Also ask to speak with one of our Registered
Dietitians who can assess your diet and provide recommendations on ways to improve your nutrition status, as well
as provide suggestions on foods to eat when you are not feeling well.
3. Is it true that sugar “feeds” cancer and should I therefore avoid all sugar in my
diet?
There has been increasing interest about the impact of sugar on cancer. Recent studies suggest that a diet high in
simple sugar may increase the risk of developing cancer. While the association has been noted, we are still unsure
of the cause. Is it that a diet high in simple sugar is usually deficient in cancer fighting nutrients, or that simple
sugar causes a surge in insulin, possibly increasing the growth of cancer cells. Despite the lack of solid research
quite a number of books and web-sites prematurely advise people with cancer to eliminate sugar as part of a cancer
prevention diet. However, it would be unhealthy to avoid all food sources of simple sugars since this would
For more information, call 1-800-789-PENN (7366) or
visit our web sites: pennmedicine.org/abramson
and oncolink.org
include fruits, vegetables and grains. These foods are the prime source of nutrients and compounds that have been
shown to reduce cancer risk.
The way to prevent surges in insulin levels is by reducing your intake of foods that are very high in simple sugar,
such as sweets and sodas, or by combining simple sugars with foods that have fiber, protein and fat which slow
their absorption. Based on research the American Cancer Society issues the following recommendations
concerning the inclusion of carbohydrates in the diet to reduce cancer risk:
• Eat 5 or more servings of a variety of vegetables and fruits each day.
• Eat other foods from plant sources several times each day (whole grains, beans, nuts,etc)
• Limit the amount of refined carbohydrates, including pastries, sweetened cereals, soft drinks, and sugar
you eat.
4. Is it safe to eat soy foods and flaxseed if I have estrogen receptor positive breast
cancer?
There is currently too little information available on the affect of flaxseed and soy on breast cancer. Phytoestrogens
(plant estrogens) are present in soy foods and to a much lesser extent in flaxseed. The assumption is that the plant
estrogens may bind to the estrogen receptor sites, thus preventing the body's estrogen from binding and therefore
acting as a protector from breast cancer. However, there is also the possibility that phytoestrogens may act as
triggers and actually increase cancer risk. Unfortunately, the research is still inconclusive. For that reason some
doctors feel that women with estrogen positive breast cancer or who are on Tamoxifen should limit their intake of
isoflavones (the type of plant estrogens in soy) until we have a better understanding of their effects on breast
tumors. The current recommendation is to limit your intake of foods containing plant estrogens to no more than 50
mg of isoflavones per day. The amounts of isoflavones in common soy foods are as follows; soy milk (30 mg/8
oz), tofu (35 mg/1/2 cup),tempeh (35-mg/1/4 cup), roasted soy nuts (60 mg/1/4 cup) and soy protein powder
(approximately 60 mg/2 scoops). While soy foods in moderation can still be a part of your diet, it is recommended
to avoid soy supplement powders and pills since they are very concentrated sources of isoflavones. In regards to
flaxseed, it is believed to be safe in recommended amounts of 1-2 Tablespoons (ground flaxseed) per day. It is also
a great source of healthy Omega 3 fatty acids.
5. Do I need to buy all organic fruits and vegetables to protect myself against
pesticides?
Many studies have been done looking at pesticide exposure from commercially grown fruits and vegetables. These
studies show very little evidence of cancer risk from pesticides and other chemical residues in foods. Frightening
headlines or web sites stating that pesticides cause cancer are based solely on animal studies using doses of
pesticides high above those normally found in foods. Additionally, the United States does regulate the amounts of
pesticides and other contaminants used in produce to keep amounts at safe levels. Overall, research shows that the
health benefits of eating produce far outweigh the risk of pesticide exposure so there is no need to spend extra
money on organic produce. If you choose organic anyway, look for produce that carries the “Certified Organic”
For more information, call 1-800-789-PENN (7366) or
visit our web sites: pennmedicine.org/abramson
and oncolink.org
label. Also, remember to thoroughly wash all produce with water. This removes most residues. Special fruit or
vegetable rinses are not necessary or any more effective than water.
6. Is it safe to drink alcohol?
There is convincing evidence that alcohol increases the risk of many cancers, including breast cancer. It is
recommended that if you drink, to limit yourself to no more than one drink per day and no more than 3-4 drinks
per week. If you don’t drink, it is best not to start.
7. I have heard that weight gain is common with breast cancer treatment. Is this
true? If so, how can I prevent it?
Researchers are still trying to pin point the cause for the weight gain that often occurs in women who have
received chemotherapy for breast cancer. Research has found that overeating is not a cause, but lack of activity
may be a factor. (J Clin Oncol 2001;19:2367-2368,2381-2389). Loss of muscle and an increase in body fat may
contribute to weight gain by lowering the metabolism. In addition, hormonal changes may play a role. To prevent
weight gain, it is advised to eat a low-fat diet focused on vegetables, fruits, whole grains, low-fat dairy products,
and lean protein sources.
However, if your appetite is poor during cancer treatment, it is better to eat anything in order to maintain your
weight since weight loss during cancer treatment is not advised.
If you find that you are gaining weight or would like more guidance with your diet, feel free to request a free
consultation with one of our Cancer Center Dietitians.
8. What are the overall diet recommendations for someone who has breast
cancer?
Research has shown that there are diet and life style factors that do seem to be protective against cancer in general.
An article entitled "American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention:
Reducing the Risk of Cancer with Healthy Food Choices and Physical Activity" in the CA: A Cancer Journal for
Clinicians Vol 52 No 2 p 92-119 provides a very thorough and extensive review of the impact of nutrition on
reducing cancer risk.
Overall, obesity and a sedentary life style are associated with an increase risk of breast cancer. Diets that are high
in vegetables and fruits may decrease risk, although the degree that they decrease risk and the specific nutrients
that provide the protection are still being studied. It is recommended to increase servings of fruits and vegetables to
at least 5-7 servings (total) per day for the greatest nutrient benefit. Also, alcohol does slightly increase risk and
should be consumed only in moderation with a maximum of one drink per day. So, overall, the recommendation is
a higher fruit and vegetable intake, less animal products (i.e. meats, animal fats, and whole milk dairy), soy in
moderation, alcohol in moderation, and regular exercise to prevent weight gain and obesity. Refer to the ‘Diet
Guidelines for Breast Cancer’ for more specific information.
For more information, call 1-800-789-PENN (7366) or
visit our web sites: pennmedicine.org/abramson
and oncolink.org