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From the Townsend Letter
August/September 2006


Nutritional Influences on Illness
The Cancer Prevention Diet
by Melvyn R. Werbach, MD

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An enormous literature has accumulated that suggests diet has a major influence on cancer. In populations consuming a Western diet, perhaps 40% of all cancer incidence among men and nearly 60% among women is believed to be diet-related.1 Not all cancers appear to be equally influenced by diet; some cancers particularly affected by what we eat are those of the gastrointestinal tract, breast, uterine endometrium, and prostate. For bowel and breast cancers, for example, up to 80% may be prevented by dietary changes.2

What are the most important characteristics of a diet that minimizes cancer risk? The results of animal studies suggest that the single most powerful and consistent dietary influence on carcinogenesis is simply energy restriction.3 Thus the diet should be low in fat. In addition to epidemiological studies relating fat intake to cancer incidence, animals fed high-fat diets develop cancers at diet-responsive sites more readily than animals on low-fat diets.4

Protein intake should be relatively low, since high levels of protein consumption are associated with an increased risk of many diet-responsive cancers,5 and there is substantial evidence that the Western diet is excessively rich in protein. By contrast, dietary fiber intake, which is far too low in the usual Western diet, should be increased.6

Processed sugar, by contrast, should be restricted. Sugar, for example, increases the mouth-to-anus transit time and increases the fecal concentration of bile acids; this may explain its association with colon cancer.7 Also, while complex carbohydrates appear to be protective, sugar intake is directly associated with the risk of breast cancer.8

All these dietary goals can be met or approached by simply increasing the consumption of fruits and vegetables – which are protective against all the major cancers2 – while decreasing the consumption of red meat.9 Generally low in fat and protein and high in fiber, fruit and vegetable consumption can substantially reduce cancer risk.10 Five servings daily is the absolute minimum recommendation; yet, in the United States, only one in eight adults say they meet that goal.11 (A serving is, for example, one half cup of chopped raw or cooked vegetables, three-quarters of a cup of juice, or a piece of fruit.)

Alcohol should be minimized, as the chronic consumption of alcoholic beverages is a significant cause of malignant tumors of the oral cavity, pharynx, larynx, esophagus, and liver.12 Although a much smaller contributor to cancers of the large bowel and breast, the high prevalence of these lesions makes the contribution of alcohol important.12 In addition to acting as a cocarcinogen, alcohol may promote carcinogenesis indirectly by inducing marginal vitamin and mineral deficiencies that, in turn, are associated with increased cancer risk.13

Smoked, pickled, and salt-cured foods, as well as meats (such as hot dogs) that have an artificial red color, and meats that are broiled or otherwise subjected to high-temperature cooking, should also be minimized. Sources of nitrites, nitrosamines, and polycyclic aromatic hydrocarbons, which cause cancer in animals, their consumption has been associated with the risk of gastric cancer as well as certain other malignancies such as brain tumors and leukemia.14

Cancer is such a dreadful disease for both sufferers and their loved ones. If you could inspire your patients to modify their diets, you would cut their risk in half. Isn't that an intervention well worth making?

1. Wynder EL, Gori GB. Contribution of the environment to cancer incidence: an epidemiologic exercise. J Natl Cancer Inst. 1977; 58:825-32.
2. Cummings JH, Bingham SA. Diet in the prevention of cancer.
BMJ. 1998; 317:1636-40.
3. World Cancer Research Fund, and American Institute for Cancer Research.
Food, Nutrition and the Prevention of Cancer: a Global Perspective. Washington, DC: American Institute for Cancer Research, 1997.
4. Carroll KK. Dietary fats and cancer.
Am J Clin Nutr. 1991; 53:1964S-7S.
5. Youngman LD. Protein restriction (PR) and caloric restriction (CR) compared: effects on DNA damage, carcinogenesis, and oxidative damage.
Mutat Res. 1993; 295(4-6):165-79.
6. Weisburger JH et al. Protective mechanisms of dietary fibers in nutritional carcinogenesis.
Basic Life Sci. 1993; 61:45-63.
7. Bostick RM, Potter JD, Kushi LH, et al. Sugar, meat, and fat intake, and non-dietary risk factors for colon cancer incidence in Iowa women (United States).
Cancer Causes Control.1994; 5:38-52.
8. Carroll KK. Dietary factors in hormone-dependent cancers. In M Winick, Ed.
Current Concepts in Nutrition, Volume 6: Nutrition and Cancer. New York, John Wiley & Sons, 1977:25-40.
9. Byers T et al. American Cancer Society guidelines on nutrition and physical activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity.
CA Cancer J Clin. 2002; 52:92-119.
10. Willett WC. Micronutrients and cancer risk.
Am J Clin Nutr. 1994; 59(suppl):1162S-5S.
FDA Consumer. March 1994.
12. Poschl G, Seitz HK. Review: Alcohol and cancer.
Alcohol Alcohol. 2004; 39(3):155-65.
13. Garro A, Lieber C. Alcohol and cancer.
Ann Rev Pharmacol Toxicol. 1990; 30:219-49.
14. Sarasua S, Savitz DA. Cured and broiled meat consumption in relation to childhood cancer: Denver, Colorado (United States).
Cancer Causes Control. 1994; 5(2):141-8.

If you are interested in how diets and nutrients can help patients improve their health, you will want a copy of Dr. Werbach's Textbook of Nutritional Medicine. For information or a free brochure on all Dr. Werbach's books, contact Third Line Press Inc., 4751 Viviana Drive, Tarzana, California 91356, USA; 818-996-0076; Fax: 818-774-1575;; e-mail:


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