Understanding the Value of Dietary Supplements and Cancer Treatment

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The following question was answered by Paul Hutson, PharmD, a pharmacist and associate professor in the University of Wisconsin School of Pharmacy. In addition, he is an associate member of the UW Paul P. Carbone Comprehensive Cancer Center, and has a clinical research focus on symptom management and palliative care.
holding a pillQ. Should I take botanicals or vitamins during chemotherapy, radiation therapy, or after treatment to protect my healthy cells from the toxicity of treatment and to prevent recurrence?
A. Cancer patients, their friends and family, seeking ways to boost the effectiveness of treatment and minimize side effects, often look to dietary supplements. The media and marketers also generate interest in natural products or vitamins. Having so many choices makes it difficult to determine what supplements can or should be part of cancer care.
Patients need to focus first on a balanced diet which emphasizes fruits, vegetables, fish and whole grains. Dieticians can help them develop tasty, nutritious and quick-to-prepare meal plans to use during and after treatment.
Drinking green tea is also an option; recent laboratory studies demonstrated tea extracts may suppress the growth of several types of cancer. Daily multivitamins are also appropriate.
Breast and Prostate Cancer
Some women consider using soy protein and extracts such as genistein while being treated for breast cancer. Marketers and some scientists suggest soy flavonoids act like tamoxifen or raloxifene, and also may inhibit cellular growth. Unfortunately, the concentrations of genistein and other flavoinoids needed to inhibit cellular growth are far greater than those available in even large doses of soy protein or genistein extracts.
More importantly, the long term effect of soy on hormonallystimulated cancers such as breast cancer is unknown, and there is no evidence that increased soy or soy extracts decrease the risk of cancer recurrence.
Many breast cancer patients who are taking tamoxifen, and some prostate cancer patients using hormone blockers, experience menopause-like symptoms and may consider dietary supplements such as:
  • Soy
  • Soy extracts
  • Red clover
  • Black cohosh
  • Vitex
  • Evening primrose oil
  • Dong quai

Most studies show that when compared against a placebo, there is little benefit of botanicals for menopausal symptoms. There is also an unknown likelihood that the extracts may stimulate the growth of any microscopic, residual disease.


St. John's Wort


St. John’s wort, commonly used to treat depression, should not be used by chemotherapy patients. It has been proven to increase the rate of removal of many drugs, which decreases the concentration of many chemotherapy drugs, hindering their effectiveness.


Antioxidants - Not Effective to Combat Toxicity


Chemotherapy and radiation patients sometimes wonder about using antioxidants or vitamin replacements to protect normal cells from toxic treatments. There is no clinical evidence showing large amounts of antioxidants decrease the overall toxicity of chemotherapy, and taking high doses of antioxidants may actually lower the ability of state-of-the-art radiation therapy, such as tomotherapy, to kill cancer cells.


Effects on Cardiovascular and Bone Health


When contemplating dietary changes, patients should also consider how cancer treatment affects their long term health, particularly the impact on their cardiovascular and bone structure.


Aging decreases bone density, but hormone blockers for prostate or breast cancer accelerate this bone weakening. Patients must ensure they are taking sufficient calcium, about 1 to 1 1/2 grams daily, especially in Wisconsin - where many people are Vitamin D deficient. In addition, there is early evidence that Vitamin D-like drugs may have antitumor effects, especially for prostate cancer.


For cardiovascular health, research has shown that fish and fish oil may decrease blood triglyceride concentrations, and that dietary fiber and soy decrease cholesterol. A daily glass of red wine, purple grape juice or cranberry juice also has demonstrated benefits.


Most clinicians encourage patients to concentrate on a well-balanced meal plan that provides energy and the needed combination of nutrients, rather than relying on botanical supplements and megavitamins.

Date Published: 07/26/2007

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