The role of your cancer health professional is to create an environment of openness and trust, and to help in making informed decisions about alternative/ complementary therapies. Collaboration will improve the safe integration of all therapies during your experience with cancer. The "Summary" and "Professional Evaluation/ Critique" sections of this Unconventional Therapies manual are cited directly from the medical literature, and are intended to help in the objective evaluation of alternative/ complementary therapies.
Summary
"For most patients, even patients with cancer, vitamins are not necessary if the patient can eat a reasonably well balanced diet." (Dutcher)
Description/ Source/ Components
"Thirteen vitamins and eighteen minerals are essential to life and health. Despite the fact that only milligrams - tiny, minute amounts - of each vitamin are needed, vitamins are essential to all of the body's biochemical processes. They are required to convert food in to energy and to help the body manufacture hormones, blood cells, and nervous system chemicals." (Cassileth)
"Vitamins are substances that the body requires for good health and development. The majority of vitamins are not made by the body itself, so they must be obtained from food or through vitamin supplements." (Ontario)
"Except for three - D, B5, and B7, which come in part from other sources - vitamins are obtained entirely from food." (Cassileth)
"A prudent diet with the normal high fruit, high vegetable, low fat intake will provide vitamin and mineral requirements for cancer prevention. Vitamin supplements are not necessary if intake is sufficient through the diet recommended by the Canada Food Guide." (Band)
Proponent/ Advocate Claims - Use in Preventing Cancer
"Antioxidant vitamins, which include beta-carotene (pro-vitamin A), vitamin E, and vitamin C, are hypothesized to decrease cancer risk by preventing tissue damage by trapping organic free radicals and/or deactivating excited oxygen molecules, a by-product of many metabolic functions." (Hennekens)
"The antioxidant vitamins and minerals associated with antioxidant enzymes are important components of the overall antioxidant protection found within cells." (Bendich)
"Observational epidemiologic studies have suggested a possible decrease in the prevalence of cancer in people who consume higher amounts of fruits and vegetables, foods high in beta-carotene, and this decrease may be through their antioxidant effect. The literature is rife with anecdotal reports of antioxidant properties of many foods or food additives." (Spencer)
Professional Evaluation/ Critique - Use in Preventing Cancer
"At this moment the data are insufficient to make recommendations for vitamin supplementation to prevent cancer." (van Poppel F)
"Antioxidant supplements turned out to be no substitute for the foods themselves. Supplements do not produce the same beneficial results seen with vegetables and fruits, probably because of currently unknown interactions with other helpful ingredients. There are no shortcuts here." (Cassileth)
"Epidemiological studies suggest that certain vitamin supplements may reduce the risk of some cancers. However, observational studies can be compromised by confounding, because supplement use is related to other factors that affect cancer risk... Supplement users were statistically more likely to exercise regularly, eat four or more servings of fruits and vegetables per day, follow a low-fat diet pattern, and believe in a connection between diet and cancer. Those investigating the benefits and risks of vitamin and mineral supplements need to be aware of the lifestyle characteristics of supplement users to assess the potential for bias in their studies." (Patterson)
"Greenberg et al. reported negative results when three antioxidant vitamins (beta carotene, vitamin C, and vitamin E) were given over a four-year period to test their efficacy in preventing colorectal adenoma, a surrogate outcome for colorectal cancer." However, the study time period may not "have been long enough for a change in the incidence of adenoma to be observed." (Burke)
"Scientific studies indicate that the necessary nutrients are provided by the average balanced diet, and that only certain groups of people require supplements: pregnant women, young children, alcoholics, those with diseases that inhibit absorption of nutrients, postmenopausal women trying to prevent osteoporosis, and people whose diets do no provide the required nutrients." (Cassileth)
Proponent/ Advocate Claims - Use in Treating Cancer
"Multiple antioxidant vitamin supplements together with diet and lifestyle modifications may improve the efficacy of standard and experimental cancer therapies." (Prasad)
"In our study, (Ingram et al 1992) we demonstrated strong association for beta-carotene and vitamin C consumption with a degree of improvement in differentiation [degree of improvement in grade or speed of growth] with increasing consumption of these nutrients" (Ingram)
Professional Evaluation/ Critique - Use in Treating Cancer
"Neither vitamins nor other dietary supplements cure cancer." (Cassileth)
"There are important distinctions between dietary supplements in the form of the vitamin pill that many take each morning and products aimed at treating illness." (Cassileth)
There is at least a theoretical disadvantage in the use of anti-oxidants during radiation therapy (which works via oxidation processes). (Rheaume)
"Oxidation reactions, which are frequently destructive to biologic molecules and involve combining a substance with oxygen, appear to initiate apoptosis and move it along. ["Apoptosis, or programmed cell death, is an intricately choreographed form of suicide by irretrievably damaged cells, including those already on their way to becoming cancerous."] Too much antioxidant, researchers theorize, might interfere with these oxidation reactions, derailing apoptosis and leaving the precursors of cancer alive. The implications may be particularly serious for cancer patients. Chemotherapies often act by inducing apoptosis, so antioxidant vitamins, in theory, could interfere with chemotherapy." (Holzman)
"High doses of antioxidants that may help prevent cancer could make things worse once the disease has struck, a study by Dutch researchers hints.
Antioxidants such as vitamin C seem to prevent cancer by mopping up free radicals that can damage DNA. [However], Jurgen Karczewski and colleagues at Nijmegen University in the Netherlands say that free radicals can also kill cancer cells. If so, antioxidants should be bad for cancer patients because they remove radicals." (Day)
References
Band P. Vitamins and cancer (consensus statement) 1993 June 4. (BCCA Cancer Information Centre search file 231)
Bendich A. Antioxidant micronutrients and immune responses. Annals of the New York Academy of Sciences 1990 May 5;587:168-180.
Burke HB. Antioxidant vitamins and colorectal adenoma (letter). New England Journal of Medicine 1994 Dec 22;331(25):1720.
Cassileth BR. Alternative medicine handbook: the complete reference guide to alternative and complementary therapies. New York: W.W. Norton & Co., 1998:65-71.
Day M. Cancer Catch. New Scientist 1997 Sept 13;16.
Dutcher JP. Do cancer patients need vitamins? Primary Care & Cancer 1990 Aug;10(8):19.
Hennekens CD. Antioxidant vitamins and cancer. The American Journal of Medicine 1994 Sept 26;97(Suppl 3A):3A-2S-3A-4S.
Holzman D. Do antioxidants promote cancer? Alternative and Complementary Therapies 1997 June:167-9.
Ingram D et al. Diet and subsequent survival in women with breast cancer. British Journal of Cancer 1994;69:592-595.
Ontario Breast Cancer Information Exchange Project. Guide to unconventional cancer therapies. 1st ed. Toronto: Ontario Breast Cancer Information Exchange Project, 1994:117-119.
Patterson RE, et al. Cancer-related behavior of vitamin supplement users. Cancer Epidemiol Biomarkers Prev 1998;7:79-81.
Prasad KN, et al. High doses of multiple antioxidant vitamins: essential ingredients in improving the efficacy of standard cancer therapy. J Am Coll Nutr 1999;18:13-25.
Rheaume D. BC Cancer Agency verbal communication 1996.
Spencer JW, Jacobs JJ. Complementary/alternative medicine: an evidence based approach. Toronto: Mosley, 1999:133.
van Poppel F, van den Berg H. Vitamins and cancer. Cancer Lett 1997;114:195-202.
Revised February 2000