When it comes to cancer there are no guarantees.However, there are choices you can make to significantly reduce your risks.
Cancer refers to a large number of diseases categorized by unregulated replication of cells. This may result in cancers that may affect many different body systems, commonly the colon, breast, prostate, and lung. Other less common diseases include cancers of the brain, bone, blood (leukemia), bladder, skin (melanoma), pancreas, uterus, esophagus, head, and neck.
The contents of this article are limited to information about diet and to a discussion of cancer prevention—not treatment. Prevention of cancer in a person who has never had cancer is called “primary” prevention. Primary prevention is the focus of this article. This article includes a discussion of studies that have assessed whether certain dietary ingredients may be beneficial in connection with the reduction of risk of developing cancer.
This information is provided solely to aid consumers in discussing supplements with their healthcare providers. It is not advised nor is this information intended to advocate, promote, or encourage self-use of this information for cancer risk reduction. Some studies suggest an association between high blood or dietary levels of a particular dietary ingredient with a reduced risk of developing cancer. Even if such an association were established, this does not mean that dietary supplements containing large amounts of the dietary ingredient will necessarily have a cancer risk reduction effect.
Prevention of a recurrence in a cancer patient who is in remission is called “secondary” prevention. Whether the information in this article would be helpful to people interested in secondary prevention is, for the most part, unknown. For people who are undergoing cancer treatment, there is preliminary evidence that a healthy diet carries benefits even after diagnosis, though dietary changes should be reviewed with the treating doctor.
Cancer is the second leading cause of death in Americans. Information on the prevention of breast, colon, lung, and prostate cancers is not provided in this article. To find out more about these specific forms of cancer, read the Breast Cancer Prevention, Colon Cancer Prevention, Lung Cancer Prevention, and Prostate Cancer Prevention articles.
The following dietary changes have been studied in connection with cancer.
Alcohol consumption significantly increases the risk of cancers of the mouth (oral/oropharyngeal cancer), throat (esophageal cancer), and voice box (laryngeal cancer), particularly in conjunction with cigarette smoking.1 , 2 , 3 Most studies documenting these associations also report that former drinkers have significantly lower risks for these cancers compared with current drinkers. Strong correlations between alcohol consumption and the risk of having liver cancer have also been reported.4 , 5
Little is known about the effect of alcohol intake on the risk of female cancers other than breast cancer. Of the few published studies, findings have been inconsistent.6 , 7 , 8 , 9
Whole grains (such as rye, brown rice, and whole wheat) contain high amounts of insoluble fiber—the type of fiber some scientists believe may help protect against a variety of cancers. In an analysis of the data from many studies, people who eat relatively high amounts of whole grains were reported to have low risks of lymphomas and cancers of the pancreas, stomach, colon, rectum, breast, uterus, mouth, throat, liver, and thyroid.10 Most research focusing on the relationship between cancer and fiber has focused on breast and colon cancers.
Consuming a diet high in insoluble fiber is best achieved by switching from white rice to brown rice and from bakery goods made with white flour or mixed flours to 100% whole wheat bread, whole rye crackers, and whole grain pancake mixes. Refined white flour is generally listed on food packaging labels as “flour,”“enriched flour,”“unbleached flour,”“durum wheat,”“semolina,” or “white flour.” Breads containing only whole wheat are often labeled “100% whole wheat.”
The following two possibilities are both strongly supported by research findings:
Compared with meat eaters, most,11 but not all,12 studies have found that vegetarians are less likely to be diagnosed with cancer. Vegetarians have also been shown to have stronger immune function, possibly explaining why vegetarians may be partially protected against cancer.13 Female vegetarians have been reported to have lower estrogen levels compared with meat-eating women, possibly explaining a lower incidence of uterine and breast cancers.14 A reduced risk for various cancers is only partly,15 not totally,16 explained by differences in body weight, smoking habits, and other lifestyle issues.
Consumption of fruits and vegetables is widely accepted as lowering the risk of most common cancers.17 Many doctors recommend that people wishing to reduce their risk of cancer eat several pieces of fruit and several portions of vegetables every day. Optimal intakes remain unknown.
Most doctors also recommend that people should not consider supplements as substitutes for the real thing. Some of the anticancer substances found in produce have probably not yet been discovered, while others are not yet available in supplement form. More important, some research, particularly regarding synthetic beta-carotene, does not support the idea that taking supplements has the same protective value against cancer as does consumption of fruits and vegetables.
Flavonoids are found in virtually all herbs and plant foods. Consumption of flavonoid-rich onions and apples contain large amounts of one flavonoid called quercetin. Consumption of flavonoids in general, or quercetin-containing foods in particular,18 has been associated with protection against cancer in some,19 but not all,20 preliminary studies.
Tomatoes contain lycopene—an antioxidant similar in structure to beta-carotene. Most lycopene in our diet comes from tomatoes, though traces of lycopene exist in other foods. Lycopene inhibits the proliferation of cancer cells in test tube research.21
A review of published research found that higher intake of tomatoes or higher blood levels of lycopene correlated with protection from cancer in 57 of 72 studies. Findings in 35 of these studies were statistically significant.22 Evidence of a protective effect for tomato consumption was strongest for cancers of the prostate, lung, and stomach, but some evidence of a protective effect also appeared for cancers of the pancreas, colon, rectum, esophagus (throat), mouth, breast, and cervix.
Cabbage, Brussels sprouts, broccoli, and cauliflower belong to the Brassica family of vegetables, also known as “cruciferous” vegetables. In test tube and animal studies, these foods have been associated with anticancer activity,23 possibly due to several substances found in these foods, such as indole-3-carbinol,24 glucaric acid (calcium D-glucarate),25 and sulforaphane.26 In a preliminary human study, people who ate cruciferous vegetables were reported to have a lower-than-average risk for bladder cancer.27
In one report, high consumption of hot dogs was associated with an almost tenfold increase in the risk of childhood leukemia when compared with low consumption.28 In another report, maternal consumption of hot dogs and childhood consumption of hamburgers or hot dogs at least once per week were associated with a doubling of the risk of cancers in children.29 A review of nine studies found an association between consumption by pregnant women of cured meat and the risk of brain cancer in their offspring.30 These associations do not yet constitute proof that eating hot dogs or hamburgers causes cancer in children, and evidence linking cured meat consumption to childhood cancers remains somewhat inconsistent.31
In the report studying the effects of eating hot dogs and hamburgers, the association between meat eating and leukemia was weakest among children who took vitamin supplements. Processed meats, such as hot dogs, contain nitrates and nitrites—precursors to carcinogens. Antioxidants found in multivitamins keep nitrates and nitrites from converting into those carcinogens. Therefore, the association between vitamin consumption in children and protection against childhood cancers remains plausible, though unproven.
Fish eaters have been reported to have low risks of cancers of the mouth, throat, stomach, colon, rectum, pancreas,32 lung,33 breast,34 and prostate.35 The omega-3 fatty acids found in fish are thought by some researchers to be the components of fish responsible for protection against cancer.36
Years ago, researchers reported the greater the consumption of coffee in a country, the higher the risk of pancreatic cancer in that country.37 An analysis of data from studies published between 1981 and 1993 did find some association between high consumption of coffee and an increased risk of pancreatic cancer.38 Surprisingly, however, the same report found that people drinking only one or two cups of coffee per day had, on average, a lower risk of pancreatic cancer compared with people who never drink coffee.
Most,39 , 40 , 41 but not all,42 published reports have shown coffee drinkers are at increased risk of bladder cancer, though in one case the relationship was found only in men.43 In another study, the association was found only with caffeinated coffee.44 A review of 35 trials found a small (7%) increased risk of bladder cancer in coffee drinkers compared with people not drinking coffee—a difference not statistically significant.45
Scientists have known for many years that severe restriction of calories dramatically reduces the risk of cancer in laboratory animals.46 Scientists speculate that caloric content of the human diet may also affect cancer rates,47 though much less is known about the effect, if any, of moderate caloric restrictions in humans. In one report, adults with cancer were more likely to have consumed more calories during childhood compared with healthy adults.48 In other reports, attempts to find associations between reduced intake of calories and cancer have produced mixed results.49 , 50 , 51
Only severe restriction in caloric intake provides significant protection in animal studies. As most people are unlikely to severely restrict calories, the association between caloric restriction and protection from cancer may ultimately prove to only be of academic interest.
In studying data from country to country, incidence of ovarian cancer correlates with dietary fat intake.52 According to preliminary research, consumption of saturated fat, dietary cholesterol (as found in eggs),53 and animal fat in general54 correlates with the risk of ovarian cancer.
Preliminary studies suggest dietary fat may correlate with the risk of uterine cancer.55 Some of the excess risk appears to result from increased body weight that results from a high-fat diet.56
Many years ago, researchers reported that animals on a high-fat diet formed skin cancers more rapidly than did other animals.57 Although some preliminary human research has found no relationship between dietary fat intake and the risk of skin cancer,58 precancerous lesions of the skin have been prevented in people put on a low-fat diet.59
A chain of carbon atoms in which several are not attached to the maximum possible amount of hydrogen is called “polyunsaturated”––in other words, unsaturated with hydrogen in several places. When nutrition researchers talk about polyunsaturated fatty acids, they are often referring primarily to linoleic acid—a fatty acid found in nuts and seeds and most vegetable oils.
In animal research, the consumption of polyunsaturated fatty acids increases the risk of some cancers.60 However, in humans, most,61 , 62 , 63 though not all,64 reports do not find an association between polyunsaturates and cancer risks.
A preliminary study has reported an association between an increasing intake of sugar or sugar-containing foods and an increased risk of gallbladder cancer.65 Whether this association exists because sugar directly promotes cancer or because sugar consumption is only a marker for some other dietary or lifestyle factor remains unknown.
In preliminary research, increasing intake of salt correlates with increased risk of stomach cancer.66 , 67 Associations between foods preserved with salt and the risk of cancers of the head and neck have also been reported.68
Animal studies suggest that the antioxidant or immune-enhancing effect of whey protein may produce anti-cancer effects.69 , 70 , 71 Preliminary human case reports suggest that 30 grams per day of whey protein may improve responses to anti-cancer medications, but more research is needed.72
1. Mashberg A, Boffetta P, Winkelman R, Garfinkel L. Tobacco smoking, alcohol drinking, and cancer of the oral cavity and oropharynx among U.S. veterans. Cancer 1993;72:1369-75.
2. Cheng KK, Duffy SW, Day NE, et al. Stopping drinking and risk of oesophageal cancer. BMJ 1995;310:1094-7.
3. Deleyiannis FW-B, Thomas DB, Vaughan TL, Davis S. Alcoholism: independent predictor of survival in patients with head and neck cancer. J Natl Cancer Inst 1996;88:542-9.
4. Makimoto K, Higuchi S. Alcohol consumption as a major risk factor for the rise in liver cancer mortality rates in Japanese men. Int J Epidemiol 1999;28:30-4.
5. Donato F, Tagger A, Ciesa R, et al. Hepatitis B and C virus infection, alcohol drinking, and hepatocellular carcinoma: a case-control study in Italy. Brescia HCC study. Hepatology 1997;26:579-84.
6. Parazzini F, La Vecchia C, D'Avanzon B, et al. Alcohol and endometrial cancer risk: findings from an Italian case-control study. Nutr Cancer 1995;23:55-62.
7. Swanson CA, Wilbanks GD, Twiggs LB, et al. Moderate alcohol consumption and the risk of endometrial cancer. Epidemiology 1993;4:530-6.
8. La Vecchia C, Negri E, Franceschi S, et al. Alcohol and epithelial ovarian cancer. J Clin Epidemiol 1992;45:1025-30.
9. Whittemore AS, Wu ML, Paffenbarger RS Jr, et al. Personal and environmental characteristics related to epithelial ovarian cancer. II. Exposures to talcum powder, tobacco, alcohol, and coffee. Am J Epidemiol 1988;128:1228-40.
10. Jacobs DR Jr, Marquart L, Salvin J, Kushi LH. Whole-grain intake and cancer: an expanded review and meta-analysis. Nutr Cancer 1998;30:85-96.
11. Frentzel-Beyme R, Chang-Claude J. Vegetarian diets and colon cancer: the German experience. Am J Clin Nutr 1994;59(suppl):1143S-52S.
12. Kinlen LJ, Hermon C, Smith PG. A proportionate study of cancer mortality among members of a vegetarian society. Br J Cancer 1983;48:355-61.
13. Malter M, Schriever G, Eilber U. Natural killer cells, vitamins, and other blood components of vegetarian and omnivorous men. Nutr Cancer 1989;32:271-8.
14. Armstrong BK, Brown JB, Clarke HT, et al. Diet and reproductive hormones: a study of vegetarian and nonvegetarian postmenopausal women. J Natl Cancer Inst 1981:67:761-7.
15. Frentzel-Beyme R, Chang-Claude J. Vegetarian diets and colon cancer: the German experience. Am J Clin Nutr 1994;59(suppl):1143S-52S.
16. Thorogood M, Mann J, Appleby P, McPherson K. Risk of death from cancer and ischaemic heart disease in meat and non-meat eaters. BMJ 1994;308:1667-71.
17. Block G, Patterson B, Subar A. Fruit, vegetables, and cancer prevention: a review of the epidemiological evidence. Nutr Cancer 1992;18:1-29.
18. Le Marchand L, Murphy SP, Hankin JH, et al. Intake of flavonoids and lung cancer. J Natl Cancer Inst 2000;92:154-60.
19. Knekt P, Jarvinen R, Seppanen R, et al. Dietary flavonoids and the risk of lung cancer and other malignant neoplasms. Am J Epidemiol 1997;146:223-30.
20. Hertog MGL, Kromhout D, Aravanis C, et al. Flavonoid intake and long-term risk of coronary heart disease and cancer in the Seven Countries Study. Arch Intern Med 1995;155:381-6.
21. Levy J, Bosin E, Feldman B, et al. Lycopene is a more potent inhibitor of human cancer cell proliferation than either a-carotene or ß-carotene. Nutr Cancer 1995;24:257-66.
22. Giovannucci E. Tomatoes, tomato-based products, lycopene, and cancer: review of the epidemiologic literature. J Natl Cancer Inst 1999;91:317-31.
23. Beecher CW. Cancer preventive properties of varieties of Brassica oleracea: a review. Am J Clin Nutr 1994;59(suppl):1166-70S.
24. Cover CM, Hsieh SJ, Cram EJ, et al. Indole-3-carbinol and tamoxifen cooperate to arrest the cell cycle of MCF-7 human breast cancer cells. Cancer Res 1999;59:1244-51.
25. Walaszek Z, Hanausek-Walaszek M, Minton JP, Webb TE. Dietary glucarate as anti-promoter of 7,12-demethylbenz [a]anthracene-induced mammary tumorigenesis. Carcinogenesis 1986;7:1463-6.
26. Zhang Y, Kensler TW, Cho CG, et al. Anticarcinogenic activities of sulforaphane and structurally related synthetic norbornyl isothiocyanates. Proc Natl Acad Sci USA 1994;91:3147-50.
27. Michaud DS, Spiegelman D, Clinton SK, et al. Fruit and vegetable intake and incidence of bladder cancer in a male prospective cohort. J Natl Cancer Inst 1999;91:605-13.
28. Peters JM, Preston-Martin S, London SJ, et al. Processed meats and risk of childhood leukemia (California, USA). Cancer Causes Control 1994;5:195-202.
29. Sarasua S, Savitz DA. Cured and broiled meat consumption in relation to childhood cancer: Denver, Colorado. Cancer Causes Control 1994;5:141-8.
30. Bunin GR. Maternal diet during pregnancy and risk of brain tumors in children. Int J Cancer Suppl 1998;11:23-5.
31. Blot WJ, Henderson BE, Boice JD Jr. Childhood cancer in relation to cured meat intake: review of the epidemiological evidence. Nutr Cancer 1999;34:111-8.
32. Fernandez E, Chatenoud L, La Veccjoa C, et al. Fish consumption and cancer risk. Am J Clin Nutr 1999;70:85-90.
33. Pierce RJ, Kune GA, Kune S, et al. Dietary and alcohol intake, smoking pattern occupational risk, and family history in lung cancer patients: results of a case-control study in males. Nutr Cancer 1989;12:237-48.
34. Kaizer L, Boyd NF, Kriukov V, Tritchler D. Fish consumption and breast cancer risk: an ecological study. Nutr Cancer 1989;12:61-8.
35. Kune GA. Eating fish protects against some cancers: epidemiological and experimental evidence for a hypothesis. J Nutr Med 1990;1:139-44 [review].
36. Rose DP, Connolley JM. Omega-3 fatty acids as cancer chemopreventive agents. Pharmacol Ther 1999;83:217-44.
37. Binstock M, Krakow D, Stamler J, et al. Coffee and pancreatic cancer: an analysis of international mortality data. Am J Epidemiol 1983;118:630-40.
38. Nishi M, Ohba S, Hirata K, Miyake H. l Dose-response relationship between coffee and the risk of pancreas cancer. Jpn J Clin Oncol 1996;26:42-8 [metaanalysis].
39. Donato F, Boffetta P, Fazioli R, et al. Bladder cancer, tobacco, coffee and alcohol drinking in Brescia, northern Italy. Eur J Epidemiol 1997;13:795-800.
40. Rebelakos A, Trichopoulos D, Tzonou A, et al. Tobacco smoking, coffee drinking, and occupation as risk factors for bladder cancer in Greece. J Natl Cancer Inst 1985;75:455-61.
41. Vena JE, Freudenheim J, Graham S, et al. Coffee, cigarette smoking, and bladder cancer in western New York. Ann Epidemiol 1993;3:586-91.
42. Jensen OM, Wahrendorf J, Knudsen JB, Sørensen BL. The Copenhagen case-control study of bladder cancer. I. Effect of coffee and other beverages. Int J Cancer 1986;37:651-7.
43. Marrett LD, Walter SD, Meigs JW. Coffee drinking and bladder cancer in Connecticut. Am J Epidemiol 1983;117:113-27.
44. D'Avanzo B, La Vecchia C, Franceschi S, et al. Coffee consumption and bladder cancer risk. Eur J Cancer 1992;28A:1480-4.
45. Viscoli CM, Lachs MS, Horwitz RI. Bladder cancer and coffee drinking: a summary of case-control research. Lancet 1993;341:1432-7.
46. Tannenbaum A. The genesis and growth of tumors. II. Effects of caloric restriction per se. Cancer Res 1942;2:460-7.
47. Macrae FA. Fat and calories in colon and breast cancer: from animal studies to controlled clinical trials. Prev Med 1993;22:750-66 [review].
48. Frankel S, Gunnell DJ, Peters TJ, et al. Childhood energy intake and adult mortality from cancer: the Boyd Orr cohort study. BMJ 1998;316:499-504.
49. Dirz MJM, van den Brandt PA, Goldbohm A, Lumey LH. Diet in adolescence and the risk of breast cancer: results of the Netherlands Cohort Study. Cancer Causes Control 1999;10:189-99.
50. Barrett-Connor E, Friedlander NJ. Dietary fat, calories, and the risk of breast cancer in postmenopausal women: a prospective population-based study. J Am Coll Nutr 1993;12:390-9.
51. Lyon JL, Mahoney AW, West DW, et al. Energy intake: its relationship to colon cancer risk. J Natl Cancer Inst 1987;78:853-61.
52. Rose DP, Boyar AP. Diet and ovarian cancer. JAMA 1985;254:2553 [letter].
53. Risch HA, Jain M, Marrett LD, Howe GR. Dietary fat intake and risk of epithelial ovarian cancer. J Natl Cancer Inst 1994;86:1409-15.
54. Cramer DW, Welch WR, Hutchison GE, et al. Dietary animal fat in relation to ovarian cancer risk. Obstet Gynecol 1984;63:833-5.
55. Hill HA, Austin H. Nutrition and endometrial cancer. Cancer Causes Control 1996;7:19-32 [review].
56. Goodman MT, Hankin JH, Wilkens LR, et al. Diet, body size, physical activity, and the risk of endometrial cancer. Cancer Res 1997;57(22):5077-85.
57. Baumann CA, Rusch HP. Effect of diet on tumors induced by ultraviolet light. Am J Cancer 1939;35:213-21.
58. Hunter DJ, Colditz GA, Stampfer MJ, et al. Diet and the risk of basal cell carcinoma of the skin in a prospective cohort of women. Ann Epidemiol 1992;2:231-9.
59. Black HS, Herd A, Goldberg LH, et al. Effect of a low-fat diet on the incidence of actinic keratosis. N Engl J Med 1994;330:1272-5.
60. Welsch CW. Relationship between dietary fat and experimental mammary tumorigenesis: a review and critique. Cancer Res 1992;52(suppl 7):2040S-8S.
61. Zureik M, Ducimetière P, Warnet JM, Orssaud G. Fatty acid proportions in cholesterol esters and risk of premature death from cancer in middle aged French men. BMJ 1995;311:1251-4.
62. Hunter DJ, Willett W. Diet, body size, and breast cancer. Epidemiol Rev 1993;15:110-32 [review].
63. Giovannucci E, Willett WC. Dietary lipids and colon cancer. Principles and Practice of Oncology 1994;9:1-12.
64. Pearce ML, Dayton S. Incidence of cancer in men on a diet high in polyunsaturated fat. Lancet 1971;I:464-7.
65. Moerman CJ, De Mesquita HBB, Runia S. Dietary sugar intake in the aetiology of biliary tract cancer. Int J Epidemiol 1993;22:207-14.
66. Joossens JV, Hill MJ, Elliott P, et al. Dietary salt, nitrate and stomach cancer mortality in 24 countries. Int J Epidemiol 1996;25:494-504.
67. Nazario CM, Szklo M, Diamond E, et al. Salt and gastric cancer: a case-control study in Puerto Rico. Int J Epidemiol 1993;22:790-7.
68. De Stefani E, Oreggia F, Ronco A, et al. Salted meat consumption as a risk factor for cancer of the oral cavity and pharynx: a case-control study from Uruguay. Cancer Epidemiol Biomarkers Prev 1994;3:381-5.
69. Hakkak R, Korourian S, Shelnutt SR, et al. Diets containing whey proteins or soy protein isolate protect against 7,12-dimethylbenz(a)anthracene-induced mammary tumors in female rats. Cancer Epidemiol Biomarkers Prev 2000;9:113-7.
70. Tsuda H, Sekine K, Ushida Y, et al. Milk and dairy products in cancer prevention: focus on bovine lactoferrin. Mutat Res 2000;462:227-33.
71. Bounous G. Whey protein concentrate (WPC) and glutathione modulation in cancer treatment. Anticancer Res 2000;20(6C):4785-92.
72. Kennedy RS, Konok GP, Bounous G, et al. The use of a whey protein concentrate in the treatment of patients with metastatic carcinoma: a phase I-II clinical study. Anticancer Res 1995;15:2643-9.
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