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Frequently Asked Questions


I have received conflicting advice regarding the use of supplemental antioxidants like vitamin C during my chemotherapy and radiation therapy.

(1) Should I avoid them or take them?

(2) Does this concern extend to the ingestion of foods containing high levels of antioxidants, like any food (such as an orange or orange juice) that has a high amount of vitamin C?

The use of various dietary supplements (vitamins, antioxidants, herbs, etc) by people with a cancer diagnosis is very common. Some reasons given for their use include:

1. Relieve unpleasant symptoms from the disease itself or side effects from the treatments
2. Protect normal healthy cells from side effects produced by treatments
3. Enhance healing after surgery
4. Augment the effects from conventional cancer treatments
5. Prevent recurrence of the original cancer and/or a new primary tumor
6. Detoxify the body both during therapy and recovery
7. Enhance the immune system

All of the above reasons have some intuitive merit. However, data from< well-designed research studies are not plentiful to help guide choices of dietary supplements for a particular type and stage of cancer, dosing, timing, interactions with other therapy/drugs, etc. The number of products available in a health food store and for sale on the Internet is mind-boggling. Where to start? Where to stop?

I consider the concern regarding the use of antioxidants during cancer therapy the most controversial question in nutritional oncology at this time. Does the ingestion of dietary supplements that are antioxidants (such as vitamin C, vitamin E, selenium, and many others) increase, decrease, or have no effect on the potential benefits of chemotherapy, radiation therapy, and other biological or hormonal therapies?

These supplements are often recommended by popular books and some individual health care practitioners to use during cancer therapy in order to help protect the body's normal cells from the harmful side effects of chemotherapy and radiation. While this outcome is certainly desirable, the real question is how this practice might affect the potentially beneficial result intended from the use of chemotherapy or radiation therapy (i.e., help extend life with an acceptable level of quality of life). One mechanism of killing cancer cells is the generation of a massive amount of free radicals within the cancer cell by various chemotherapy drugs and radiation in order to disrupt replication and growth of the cancer cells. Thus there is concern by many oncologists that consuming additional supplemental antioxidants, which eliminate free radicals, may potentially reduce the effectiveness and defeat the very purpose of choosing to undergo conventional cancer therapies like radiation and chemotherapy.

Much research still needs to be done to evaluate this question in clinical trials (human data). Although preliminary research has been done in both in test tubes and animals, human testing is the only way to really know how the addition of various dietary supplements to a conventional cancer therapy will affect survival and quality of life.

In the meantime, the question of what to do still looms. There are no clear-cut answers.

The best advice I can give you is to READ, READ, READ (cross check everything - do not believe everything you read!), and be the patient with 10,000 questions. Determine your goals and then use the questions I have outlined in my "Decision Tree" (on page 15 of my book) as a springboard for being an informed and savvy cancer patient. NEVER use one source of information as your only source of information, particularly if that source has a financial interest in the product being sold! Invest much more research time deciding what to put into your body than you have in the past when buying a home or car. You are trying to choose a course of action that offers reasonable hope, instead of hype, or even possible harm.

Ultimately, the choice of what to do is a personal one. However, I strongly recommend discussing possible choices regarding the use of dietary supplements with members of your oncology team, particularly your physicians, dietitian and pharmacist. Ask them to share their thought process and references that have led to their recommendations. Also ask them to help you understand and interpret the scientific strength of advice, articles or information you may have found in various books, from the Internet, or from other practitioners.

Some books, articles, and web sites to read as starting points for information regarding the use of herbs, vitamins, and other dietary supplements in cancer:

1.Antioxidants against Cancer, Ralph Moss, PhD, Equinox Press, 2000.
2.Choices in Healing - Integrating the Best of Conventional and Complementary Approaches to Cancer, Michael Lerner, PhD, MIT Press, 1994.
3. Dietary Options for Cancer Survivors: A guide to research on foods, food substances, herbals and dietary regimens that may influence cancer, American Institute for Cancer Research, Washington, DC, 2002.

4.Herbal Medicine, Healing & Cancer, Donald Yance, Keats Publishing, 1999.
5.Herbs against Cancer, Ralph Moss, PhD, Equinox Press, 1998.
6.Fight Cancer with Vitamins and Supplements: A Guide to Prevention and Treatment, K.N. Prasad, PhD, and K.C.Prasad, MD, Healing Arts Press, Rochester, VT, 2001.
7.Natural Compounds in Cancer Therapy, John Boik, Oregon Medical Press, Princeton, MN, 2001.
8.Tyler’s Herbs of Choice - The Therapeutic Use of Phytomedicinals, James Robbers, PhD, and Varro Tyler, PhD, ScD, Haworth Press, 1999.
9.Tyler’s Honest Herbal: a Sensible Guide to the Use of Herbs and Related Remedies, Tyler and Steven Foster, Pharmaceutical Products Press, New York, 1998.

American Botanical Council
Consumer Lab
Center for Alternative Medicine Research in Cancer
Center for Complementary and Alternative Medicine (CCAM)
Office of Dietary Supplements (NIH)
Quackwatch (Dr. Stephen Barrett)
Supplement Watch

"Possible interactions between dietary antioxidants and chemotherapy", Labriola D, and R Livingston, Oncology (Huntingt) 1999 July;13(7):1003-8, discussion 1008, 1011-12. Comments in Oncology (Huntingt) 1999 Dec;13(12):1624, 1627-28, 1631.

"Antioxidants in cancer therapy; their actions and interactions with oncologic therapies", Lamson, D and M Brignall, Alternative Medicine Review 4(5):304-329, 1999. Full article available on line.

Antioxidants and Cancer Therapy II: Quick Reference Guide
Davis W. Lamson, MS, ND, Matthew S. Brignall, ND
Alternative Medicine Review 2000 Apr;5(2):152-63.
A summary with charts of the more lengthy review cited above (Altern Med Rev. 1999 Oct;4(5):304-29) - this summary available on-line

Micronutrient Supplementation for Patients With Metastatic Cancer - Nutrition and Cancer 38(2):296-298, 2000.

Dietary Antioxidants During Cancer Chemotherapy: Impact on Chemotherapeutic Effectiveness and Development of Side Effects - Nutrition and Cancer 37(1):1-18, 2000.

J Pediatr Hematol Oncol. 2007 Jan;29(1):32-47. A strategy for controlling potential interactions between natural health products and chemotherapy: a review in pediatric oncology. Seely D, Stempak D, Baruchel S. Article available on-line.

There are additional books and websites on the Links page of my website. Inclusion here is simply meant as a source of information to evaluate further, not an endorsement.

In answering your second question regarding concern about the consumption of foods high in antioxidants, I know of no large body of research that would lead me to conclude at this time that any food should be specifically avoided during cancer therapy because of its high content of antioxidants. It is the ingestion of individual antioxidants in the isolated form of a pill, often in doses significantly higher than obtained from usual amounts of food sources, that is of greater concern. The consumption has now changed, in essence, from a nutrient level to a pharmaceutical (drug) level.

Proceeds from the sale of my books are donated to the Diana Dyer Cancer Survivors' Nutrition and Cancer Research Endowment that I have established at the American Institute for Cancer Research (AICR) in Washington, DC. I direct this endowment to exclusively fund research projects that will focus on defining nutritional strategies after a cancer diagnosis, either during treatment or recovery, which will optimize the chances for long-term survival.

The first research project that my endowment has helped to fund through AICR will be evaluating the outcome (i.e. the effectiveness of chemotherapy on extending life) of adding an antioxidant to a specific chemotherapy regime in humans. Much more research of this type should be funded by our government's National Cancer Institute to help cancer patients and physicians optimize cancer therapy.

Information regarding additional donations to this endowment or grant applications may be obtained from the Director of Development at AICR by calling 1-800-843-8114.

faq posted 12/01, updated 10/02, 1/04, 3/07


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Nutritional Concerns during Cancer Treatment (related to side effects)

Nutritional Concerns during  Cancer Treatment Can you provide a list of all chemotherapy drugs called alkylating agents that may potentially have interactions with antioxidant supplements during chemotherapy? posted 10/02
Nutritional Concerns during  Cancer Treatment Dear Diana, I am undergoing treatments for cancer and am not eating well. What should I do? posted 7/01
Nutritional Concerns during Treatment Can I drink your soy shake recipes if my oncologist or dietitian has recommended that I follow a neutropenic diet due to my low white blood cell counts? posted 5/00, updated 7/01, updated 11/02, updated 8/03
Nutritional Concerns during Treatment Should I consume antioxidants during my cancer therapy? posted 12/01, updated 10/02
Nutritional Concerns during  Treatment Can herbs interact with any of the chemotherapy drugs? posted 4/01, updated 9/02
Nutritional Concerns during  Treatment Are there any diet changes to help relieve bloating during abdominal radiation? posted 4/03
Nutritional Concerns during  Treatment Do you have diet suggestions for someone who has diarrhea after
radiation therapy for rectal cancer?
posted 1/04, updated 4/04, 11/04, 1/05
Nutritional Concerns during  Treatment Is it safe to drink green tea if I have a port for administration of my chemotherapy? posted 1/04
Nutritional Concerns during  Treatment Can you tell me foods to eat to reduce the acid in my urine and pain in my bladder and ureters? posted 2/04, updated 5/05
Nutritional Concerns during  Treatment How can I eat a diet as healthy as you suggest if I need to be
hospitalized for more than a day or two?
posted 3/04
Nutritional Concerns during  Treatment My husband is having chemotherapy treatments and has lost his sense
of taste after one treatment. Are there any foods I can prepare that will give him some relief?
posted 9/04
Nutritional Concerns during  Treatment Is there a good web site describing the nutrition related side effects from chemo drugs? posted 10/04
Nutritional Concerns during  Treatment Should I stop drinking green tea during chemotherapy to avoid consuming too many antioxidants? posted 7/05
Nutritional Concerns during  Treatment How can I use the diet recommendations on your web site and in your book to both increase my intake of cancer fighting foods for optimizing my cancer recovery and lose weight at the same time? posted 3/06
Nutritional Concerns during  Treatment What tips do you have to stay on a healthy diet during the holiday season? posted 11/06


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Soy Shake I have recently seen a lot of news articles about the relationship between vitamin D and cancer prevention. Should we all run out and get more Vitamin D supplements? posted 2/06
Soy Shake I am being treated for bladder cancer. I have heard that vitamins that might help me reduce my risk of recurrence. Do you know anything about this? posted 8/02 , updated 11/05
Soy Shake Do you have recommendations for herbs and vitamins that children should use to recover from a bone marrow transplant? posted 3/05
Soy Shake Can you provide a list of all chemotherapy drugs called alkylating agents that may potentially have interactions with antioxidant supplements during chemotherapy? posted 10/02
Soy Shake Should I consume antioxidants during my cancer therapy? posted 12/01, updated 10/02
Soy Shake Should I stop drinking green tea during chemotherapy to avoid consuming too many antioxidants? posted 7/05
Soy Shake I have recently heard that Vitamin A may be linked to osteoporosis. I see Vitamin A in nearly everything on food labels, even my soymilk. What is the connection and how much should I be consuming? posted 5/02, updated 2/03



These questions and answers are intended to be of a general informative nature. Please consult with the Registered Dietitian in your cancer center or your health care provider for nutritional advice that can be individualized to your specific medical condition.

Contact Information:
Phone/Fax: 734/996-9260

P.O. Box 130221, Ann Arbor, MI  48113

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