Nutritional and Dietary Management of the Cancer Patient

By
Stacy Steinberg, M.S., R.D., CNSD
Associate Executive Director,
The Cedars Sinai Comprehensive Cancer Center

There is a growing interest among health professionals and the public concerning the role diet plays in cancer risk reduction and control. The relationship between diet and cancer risk, however, is not clearly understood. As a result, the way such information is communicated to the lay person often is overwhelming and confusing. This confusion may lead to the pursuit of unconventional nutritional remedies such as the use of alternative dietary practices or vitamin mega-doses. Nutritional management of the patient who is not undergoing treatment and who is asymptomatic should focus on balance, variety and moderation. A balanced diet will provide the nutritional components to help a patient maintain muscle mass and strength, and to prevent body tissues and stored nutrients from breaking down. This preservation of nutritional status results in the desired enhancement of immune function.

General Dietary Guidelines

Conservatively estimated, approximately 35% of all cancer deaths in the United States may be related to diet. In fact, broader estimates report that as much as 80% of all cancers may be related to the environment, including things we eat, drink and smoke. The US Department of Agriculture and the US Department of Health and Human Services propose seven basic guidelines for to good nutrition that promote health and may help prevent chronic diseases such as cancer:

Table 1. Dietary Guidelines For Americans

• Eat a variety of foods
• Maintain ideal weight
• Choose a diet low in fat, saturated fat and cholesterol
• Choose a diet with plenty of vegetables, fruits and grain products
• Use sugars only in moderation
• Use salt and sodium only in moderation
• If you drink alcoholic beverages, do so in moderation

In 1991, the USDA sponsored the development of "The Food Guide Pyramid" to convey the message of dietary moderation, proportionality, and variety. The Pyramid suggests a range of daily servings from each of the major food groups. Although not a rigid prescription, it generally outlines daily consumption to provide your body with the foods necessary to get the right amount of nutrients and calories. (see Figure 1.)

Figure 1.

The body requires proper daily amounts of protein, carbohydrates, fat, vitamins, minerals, trace elements and water to function effectively. Variety is essential because no one food can supply all necessary daily nutrients. As previously discussed in Part I, nutrient requirements may be increased or modified when the body is under stress from infection, disease or treatment. Each nutrient provides basic ingredients from which body cells, tissues and organs maintain, reproduce and repair themselves:

• Protein provides amino acids which are used by the body to create antibodies, to fight infection, to build and repair body tissues, and to assist in many other physiological functions.
  
• Carbohydrates are used to supply energy for heat and to do the mechanical work in the system. They also may be rich in vitamins, minerals and fiber which are important contributions to the diet.
  
• Fat supplies calories needed for warmth and physical exertion and provides essential fatty acids required for growth, hormone production, cell membrane structure. and transport of fat soluble vitamins (A,D,E,K). Stored fat also is an important source of reserve energy for the body.
  
• Vitamins, Minerals, and Water are necessary to activate, regulate and control a wide variety of metabolic functions occurring in the body.
  

Iron is an important component of dietary intake because it enhances the oxygen-carrying capacity of red blood cells in the body. Lack of adequate dietary iron intake (see Figure 2. for Recommended Daily Allowances) may result in a dietary anemia, which is not always prevalent among cancer patients. More common among patients is an anemia of chronic disease, sometimes associated with the disease itself or treatment. A physician should be able to assess the particular anemia based on evaluation of serum laboratory data. Unless contraindicated due to a disease of iron metabolism, a diet rich in iron is generally recommended. While a high iron diet will not necessarily improve blood levels, it can prevent an additional dietary iron deficiency from developing. Foods rich in iron are shown below in Table 2.

Table 2. Iron Rich Foods and Their Respective Iron Content

*Iron is fortified in cereals; brands vary.

Vitamins and Other Dietary Factors in Cancer Prevention

Much attention has been placed on the so-called "antioxidant" vitamins for cancer prevention and treatment. Beta-carotene (a precursor to vitamin A) and vitamins A, C, and E are potential anti-cancer agents that may reduce the risk of cancer. However, while this reduced risk has been shown in animal studies, it has only been suggested in human studies. There is no conclusive proof that a diet rich in these antioxidants is able to affect a reduced incidence of, nor a cure for cancer in humans. While other vitamins are needed for numerous body functions, it does not appear that most of the B-complex vitamins, vitamin D or vitamin K prevent cancer in animals or humans. Among the minerals, selenium may be a potent anti-cancer agent. Selenium is required for the antioxidant enzyme glutathione peroxidase to exert its antioxidant action and strengthens the body's immune defense system In fact, some studies suggest that a combination of selenium and vitamin E in combination is more effective for cancer prevention.. Other dietary factors, such as fiber, may reduce the risk of cancer, especially cancers of the colon and rectum.

Antioxidants work to destroy free radicals, which are harmful molecules that form in the body as a result of oxidative processes of metabolism. These free radicals are highly reactive and are capable of damaging DNA, RNA, lipid and protein molecules and may be involved in the development of cancerous cells (carcinogenesis). Carcinogenesis can be described, for purposes of simplification, by a two-step process, initiation and promotion. Initiation involves a viral, chemical or irradiating carcinogen (this may be an inherited disposition), which induces irreversible changes in the cellular genetic material, yet does not actually produce tumor formation. Promotion is caused by exposure to a carcinogen called a promoter, which triggers the proliferation of cancerous cells (i.e. formation of free radicals). A promoter substance favors the development of cancer once the initiating event has taken place. Such promoters may include exposure to toxic chemicals, tobacco smoke, and possibly the diet. Promotion may be reversible if the promoter is removed or if protective substances are added prior to the development of cancerous tumors. Antioxidants function to decrease DNA damage and malignant transformation and thus may act as protective substances. The primary target of human chemoprevention (cancer-prevention) is the promotion process.

Along with vitamins A, C, E, and selenium, several enzymes also share antioxidant roles, inhibiting the formation of free radicals. Optimal doses of such vitamins, however, are unknown. Additionally, several epidemiological studies in humans have shown relationships between diets rich in beta-carotene, vitamin E and vitamin C and reduced cancer risk, however, such studies are not conclusive. Several human intervention trials are underway to study the relationship between an increased intake of supplementary vitamins A,C,E and beta-carotene and their effect on the incidence of cancer among high risk populations (i.e. smokers, asbestos workers). Most of the evidence existing thus far about the cancer-preventive role of vitamins and minerals is based on animal models and cannot necessarily be generalized to the human population. However, the possible benefits of such vitamins and minerals should not be discarded.

Table 3. Suspected Role of Diet in Cancer Risk

In order to avoid possible toxicities of overconsumption, caution must be exercised when taking vitamin and mineral supplements. Because vitamin C is water soluble, the amount of vitamin consumed in excess of the body's needs is excreted in the urine. Therefore, some people assume there are no prohibitive levels of vitamin C intake. However, excessive amount of vitamin C may cause nausea, abdominal cramps, diarrhea and in extreme cases, rebound scurvy (vitamin C deficiency syndrome) may occur after megadose therapy. Excessive vitamin C may also obscure the results of tests to detect diabetes, may counteract anticoagulant medication activity and may be harmful in people with a history of renal oxalate stones, diseases of iron metabolism, and copper metabolism. Many studies suggest that dosages of vitamin C up to 2 grams per day are unlikely to cause serious side effects in an average normal adult.

The toxicity of beta carotene is not well known. Daily intakes of 100 milligrams per day or more over extended periods may cause bronzing of the skin. Daily doses of 50,000 I.U. per day of vitamin A over extended periods may cause damage to the liver, kidney and bones, headaches, irritability, vomiting, hair loss and blurred vision. Major toxic effects in an average normal adult are unlikely with doses up to 10,000 I.U. of vitamin A per day.

Toxicity of vitamin E is rare, yet fatigue, skin reactions and abdominal discomfort have been reported with daily doses greater than 1000 I.U. for prolonged periods. According to several studies, doses up to 400 I.U. of vitamin E per day are not likely to produce major toxicities.

A total daily intake, (diet and supplement), of 500 micrograms or more of selenium may be toxic. Optimal doses of selenium for maximum health benefits are not yet known. However, animal studies suggest that the margin of safety for selenium dose is narrow.

The Recommended Daily Dietary Allowances from the Food and Nutrition Board, National Academy of Sciences-National Research Council are shown below in Figure 2.

Figure 2.

There are many ongoing studies designed to examine the role of dietary substances in cancer risk reduction as well as to analyze safety, efficacy and dosage recommendations of such substances. Cancer treatment protocols proceed through a five phase clinical trial process: 1) pre-clinical lab study, 2) animal model, 3) toxicity and safety issues, 4) phase I and II trials, and 5) intervention and clinical trials. The first generation of chemopreventive agents, such as garlic, licorice, soybeans and flaxseed, are in the clinical trial phase. Approximately 100 other pre-clinical studies are underway for substances such as beta carotene, selenium, vitamin E, ellagic acid and calcium

Calcium may play a role in the reduction of risk for colon cancer. However, since hypercalcemia is a common problem in patients with multiple myeloma and lymphomas during their disease, calcium supplementation should be carefully regulated according to serum calcium values and physician recommendations.

Conclusions

Although dietary manipulations which reduce carcinogens and increase protective nutrients may reduce the incidence of cancer, no single causative factor has been identified in current laboratory studies. Insufficient data is available to accurately predict the potential side effects of vitamin/mineral megadose supplementation over an extended time period, despite the fact that there are millions of dollars spent annually on research. Until more specific information is available about how dietary components and cancer risk interact, the Recommended Daily Allowances for vitamins and minerals (see Figure 2.) and the guidelines of The American Cancer Society should be observed. (see Table 4.)

Table 4. American Cancer Society Guidelines on Diet, Nutrition and Cancer

• Maintain desirable weight.
• Eat a varied diet.
• Include a variety of vegetables and fruits in the daily diet.
• Eat more high fiber foods, such as whole-grain cereals, legumes, vegetables and fruits.
• Cut down on total fat intake.
• Limit consumption of alcoholic beverages.
• Limit consumption of salt-cured, smoked and nitrate-preserved foods.

For References, please contact the International Myeloma Foundation.

Reference List For Nutritional and Dietary Management
of the Cancer Patient II

Balducci, L., Hardy, C.: Cancer and nutrition: A Review. Comp Ther 13(3): 60-69, March, 1987.

Barrett, S., Cassileth, B.: Dubious cancer treatment: report on alternative methods and the practitioners and patients who use them. American Cancer Society, Florida Division, 1991.

Baumgartner, T.: Antioxidants in modern nutrition. Newslines 3(3): 1-3, 1994.

Bloch, A.: Nutrition Management of the Cancer Patient. Aspen Publishers, Maryland, 1990.

Block, G., Hensen, D.E., Levine, M.: Ascorbic Acid: Biological functions and relation to cancer. Am J Clin Nutr 54(suppl): 1113, 1991.

Cameron, E., Campbell, A.: The orthomolecular treatment of cancer. II. Clinical trial of high-dose ascorbic acid supplements in advanced cancer. Chem Biol Interact 9:285, 1974.

Cameron, E., Pauling, L.: Supplemental ascorbate in the supportive treatment of cancer: Prolongation of survival times in terminal human cancer. Proc Natl Acad Sci USA 73:3685, 1976.

Cameron, E., Pauling, L.: Supplemental ascorbate in the supportive treatment of cancer: Reevaluation of prolongation of survival times in terminal human cancer. Proc Natl Acad Sci USA 75:4538, 1978.

Clifford, C., Kramer, B.: Diet as risk and therapy for cancer. Med Clin N Amer 77(4): 725-744, July, 1993.

Creagan, E.T., Moertel, C.G., O'Fallon, J.R.: Failure of high-dose vitamin C (ascorbic acid) therapy to benefit patients with advanced cancer: A controlled trial. N Engl J Med 301:687, 1979.

Dwyer, J.: Unproven nutritional remedies and cancer. Nutr Rev 50(4): 106-109, April, 1992.

Eldridge, B.: Oncology nutrition: The ambulatory care setting. Onc Nutr 2(1):3-7, 1994.

Heimburger, D., Hensrud, D.: Nutritional factors in cancer prevention. Support Line: Dietitians in Nutrition Support 16(4): 6-10, August, 1994.

Kritchevsky, D.: Dietary guidelines: The rationale for intervention. Cancer (supplement) 72(3): 1011-1014, August, 1993.

Lacy, J.: Immune function and nutrition support. RD, Sandoz Nutrition 13(3), 1993.

Lawson-Matthew, P., Clayton, J., Guillan-Cumming, D., Yates, A., Preston, E., Greaves, M., Kanis, J.: Vitamin D metabolism in myeloma. Br J Haem 73:57-60, 1989.

Marshall, C.: Vitamins and minerals: Help or harm? J.B. Lippincott Company, Philadelphia, 1983.

Moertel, C.G., Fleming, T.R., Creagan, E.T., Rubin, J., O'Connel, M.J., Ames, M.M.: High dose vitamin C versus placebo in the treatment of patients with advanced cancer who have had no prior chemotherapy: A randomized double-blind comparison. N Engl J Med 312:137-141, 1985.

Potter, J., Steinmetz, K.: There is more to vegetables and fruits than antioxidants and fiber. Proceedings of the American Association For Cancer Research 35:673-674, March, 1994.

Prasad, K.: Vitamins in cancer prevention and treatment. Healing Arts Press, Vermont, 1984.

Renneker, M.: Understanding cancer. Bell Publishing Company, Palo Alto, California, 1988.

Shils, M.: Nutrition and diet in cancer management. Modern Nutrition in Health and Disease, eight edition, volume 2. Lea & Febiger, Philadelphia, 1994.

U.S. Department of Agriculture, Human Nutrition Information Service: USDA'S food guide pyramid. April, 1992.

U.S. Department of Health and Human Services, National Institutes of Health: Diet, nutrition & cancer prevention: A guide to good food choices. May, 1987.

U.S. Department of Health and Human Services, National Institutes of Health: Eating hints: Tips & recipes for better nutrition during cancer treatment. April, 1990.

Wittes, R.E.: Vitamin C and cancer. N Engl J Med 312:178-179, 1985.