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Are There Dietary Options for Cancer Prevention? - James - 06-25-2012 07:55 PM

QUESTION: Are There Dietary Options for Cancer Prevention?

Author: Dr. Joseph Pizzorno, ND
Dr. Joseph Pizzorno, ND Chair, Scientific Advisory Board
Bioclinic Naturals Dr. Joe Pizzorno is the Founder and President of SaluGenecists Inc., Founding President of Bastyr University, and Editor-in-Chief of Integrative Medicine, A Clinician's Journal. He is the co-author of seven books including the internationally acclaimed Textbook of Natural Medicine and the Encyclopedia of Natural Medicine, which has sold over a million copies and been translated into six languages. Readers can now follow him on Twitter or directly tweet him at "@drpizzorno".
Co-authored by Joseph Katzinger, ND

Dr. Joe Katzinger consults as medical researcher and health writer with SaluGenencists, Inc. He earned his ND degree from Bastyr University, and graduated summa cum laude with a bachelors of science in honor's biochemistry from Michigan State University.

ANSWER:

The lifetime probability of being diagnosed with invasive cancer is now 44 percent for men and 38 percent for women, and an estimated total of nearly 1.6 million new cancer cases will be diagnosed in the United States in 2011. Cancer has also replaced heart disease as the leading cause of death among individuals less than 85 years old, and is responsible for one out of every four deaths.(1) Despite extraordinary spending, cancer incidence in the U.S. is the highest in the world, and has not changed significantly in 50 years.(2)

Yet this heavy toll is not set in stone, in large part because the vast majority of cancers are preventable. As much as 90-95 percent of cancers are not hereditary in nature, but are due to lifestyle (including smoking, diet, alcohol, physical inactivity, obesity and sun exposure) and environmental factors (such as toxin exposure and infection). Diet and tobacco use alone are responsible for 55-65 percent of all cancers.(3) Tobacco contains at least 50 carcinogens, increases the risk for at least 14 cancers, and is responsible for 25-30 percent of all cancer deaths.

Thus, a tremendous reduction in cancer incidence is possible, given major changes in lifestyle and improvements in environmental conditions. Most cancer prevention strategies, unfortunately, are targeted at the level of early detection rather than actual prevention. Although detection of cancers through appropriate screenings, such as clinical exam, colonoscopy, etc., are important, in this article we'd like to review natural interventions to reduce the likelihood of developing cancer, not just catching it early.

Do Genes Determine Cancer Risk?

For the most part, no. As mentioned above, only 5-10 percent of cancer incidence is determined by genetic defects. This is not to say that genes have no role in the development or progression of cancer. In some cases they have a quite profound role, as evidenced by the BRCA1 and BRCA2 genes, which carry a high risk for breast and ovarian cancer (women with mutations in the BRCA1 gene have a 65 per cent risk of developing breast cancer and a 39 percent of developing ovarian cancer by the age of 70).(4) Additionally, the role of epigenetics (changes in the gene expression without a change in gene sequence) also appears to be an important modulator of risk.(5) But emerging evidence indicates that the number of cancers caused by one or two mutations in such a direct fashion is relatively low, and that it is more likely to be the complex interactions between dozens if not hundreds of genes as well as gene-environment interactions, which determine risk. While the effects of many individual genetic mutations is probably quite small, the combined effects of many genes coupled with modulation of their expression by diet and lifestyle appears to be a much better predictor of cancer risk.(6) As one example, a study published in the New England Journal of Medicine cited a six-fold increase in risk for breast cancer among women that had 14 high risk variants (alleles) compared to women that did not have any higher risk alleles.(7)

Role of Diet & Lifestyle - Modulation of Risk

Aside from tobacco use, diet is the most important determinant of cancer risk, which makes our choice of foods one of the most empowering ways to reduce risk of disease. Results from the European Prospective Investigation into Cancer and Nutrition (EPIC) were published in 2010 in the European Journal of Cancer, and shed considerable light on the influence of diet on the risk of the most common cancers. In this prospective study, which enrolled over 500,000 participants, researchers determined that specific foods modulated cancer considerably.(8)

For example, intake of total, red and processed meat was associated with an increased risk for gastric cancer, particularly in those infected with H. pylori, while adherence to a Mediterranean diet was strongly associated with a reduction in risk. Additionally, plasma levels of vitamin C and some carotenoids were associated with a lower risk. As expected, fiber emerged as an important protector against colorectal cancer, with those consuming high amounts (35g) having approximately a 42 percent lower risk than those consuming the lowest amount (15g). Alcohol, red and processed meat were all found to increase colorectal cancer risk as well. For lung cancer, both fruit and vegetables significantly lowered the risk, particularly in smokers. This is quite interesting, given that beta-carotene supplementation has been associated with an increased risk for lung cancer among smokers, yet whole fruits and vegetables may provide a measure of protection.

In this same study, breast cancer risk was increased by a higher intake of saturated fat and alcohol, while physical activity was shown to reduce the risk. Body mass index was also directly associated with risk of breast cancer. In men, a high intake of dairy protein and calcium from dairy was associated with an increased risk of prostate cancer. This is likely due to the increase in insulin-like growth factor I by these foods, an association confirmed in this study (men with higher blood levels of this hormone also had higher risk of prostate cancer.)

While the effect of diet on cancer certainly varies by location, if any central theme has emerged it is that plantbased foods reduce the risk of cancer, while animal-based foods increase the risk, and a higher ratio of n-3 to n-6 fatty acids has an additional protective effect.(9) This may in part be due to the high concentration of carcinogenic chemicals found in animal foods, as well as to the diversity of phytochemicals found in plants. For example, cruciferous vegetables contain compounds such as glucosinolates, which affect the expression of various genes and detoxification enzymes, and make toxic substances less harmful. Estrogen metabolism has been shown to be directly influenced by detoxification enzyme activity, with quercetin and cruciferous vegetables reducing the production of genotoxic metabolites, and thereby reducing risk.(10)

Also emerging is that both inflammation and insulin resistance may play a greater role in cancer development than previously realized.(11) Indeed, some authors have even proposed excessive inflammation as a unifying theory for all cancer.(3) This may be why obesity has emerged as a contributor to cancer incidence, as has diabetes, with both conditions associated with an increase in inflammatory mediator production, hyperinsulinemia and an unfavorable production of growth factors.(12,13) Perhaps these molecular pathways explain the benefits of a more plantbased diet (which improves insulin sensitivity and reduces inflammation), as well as the protective effect of physical activity.(14) A lower protein and lower calorie diet may also have a beneficial effect through similar mechanisms.(15)

Conclusion

While cancer detection is important, the role of dietary and lifestyle changes to reduce the risk of cancer cannot be overestimated. Avoiding tobacco, consuming a diet rich in plant-based foods abundant in cruciferous vegetables and n-3 fatty acids, and maintaining a healthy BMI with ample physical activity may be among the most powerful interventions to prevent this disease. Certainly nutritional supplementation is also important, as many plant-based compounds such as curcumin, resveratrol and catechins decrease risk,(3) as does vitamin D, an effect influenced by genetic polymorphisms in the vitamin D receptor.(16) Environmental toxins are also of critical importance, and efforts to avoid exposure such as eating organic food, eliminating personal pesticide use, and reducing exposure to outdoor pollution and occupational toxins all have important protective effects.(17-19)

References:

1. Siegel R, et al. Cancer statistics, 2011: the impact of eliminating socioeconomic and racial disparities on premature cancer deaths. CA Cancer J Clin. 2011 Jul-Aug;61(4):212-36.

2. Aggarwal BB, et al. Models for prevention and treatment of cancer: problems vs promises. Biochem Pharmacol. 2009 Nov 1;78(9):1083-94.

3. Anand P, et al. Cancer is a preventable disease that requires major lifestyle changes. Pharm Res. 2008 Sep;25(9):2097-116. Epub 2008 Jul 15.

4. Antoniou A, et al. Average risks of breast and ovarian cancer associated with BRCA1 or BRCA2 mutations detected in case Series unselected for family history: a combined analysis of 22 studies. Am J Hum Genet. 2003 May;72(5):1117-30.

5. Rodríguez-Paredes M, et al. Cancer epigenetics reaches mainstream oncology. Nat Med. 2011 Mar;17(3):330-9.

6. Mavaddat N, et al. Genetic susceptibility to breast cancer. Mol Oncol. 2010 Jun;4(3):174-91.

7. Pharoah PD, et al. Polygenes, risk prediction, and targeted prevention of breast cancer. N Engl J Med. 2008 Jun 26;358(26):2796-803.

8. Gonzalez CA, et al. Diet and cancer prevention: Contributions from the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Eur J Cancer. 2010 Sep;46(14):2555-62.

9. Fu Z, et al. Well-done meat intake and meat-derived mutagen exposures in relation to breast cancer risk: the Nashville Breast Health Study. Breast Cancer Res Treat. 2011 Oct;129(3):919-28.

10. Mense SM,. Preferential induction of cytochrome P450 1A1 over cytochrome P450 1B1 in human breast epithelial cells following exposure to quercetin. J Steroid Biochem Mol Biol. 2008 May;110(1-2):157-62.

11. Tsugane S et al. Insulin resistance and cancer: epidemiological evidence. Cancer Sci. 2010 May;101(5):1073-9.

12. Harvey AE, et al. The growing challenge of obesity and cancer: an inflammatory issue. Ann N Y Acad Sci. 2011Jul;1229(1):45-52. doi: 10.1111/j.1749- 6632.2011.06096.x.

13. Xue F, et al. Diabetes, metabolic syndrome, and breast cancer: a review of the current evidence. Am J Clin Nutr. 2007 Sep;86(3):s823-35.

14. Moore SC, et al. Physical activity, sedentary behaviours, and the prevention of endometrial cancer. Br J Cancer. 2010 Sep 28;103(7):933-8.

15. Fontana L, et al. Long-term low-protein, low-calorie diet and endurance exercise modulate metabolic factors associated with cancer risk. Am J Clin Nutr. 2006 Dec;84(6):1456-62.

16. Köstner K et al. The relevance of vitamin D receptor (VDR) gene polymorphisms for cancer: a review of the literature. Anticancer Res. 2009 Sep;29(9):3511-36.

17. Belpomme, et al. The multitude and diversity of environmental carcinogens. Environmental Research 105 (2007) 414–429.

18. Irigaray P, et al. Lifestyle-related factors and environmental agents causing cancer: an overview. Biomed Pharmacother. 2007 Dec;61(10):640-58.

19. Clapp RW, et al. Environmental and occupational causes of cancer: new evidence 2005-2007. Rev Environ Health. 2008 Jan-Mar;23(1):1-37.



Dr. Joseph Pizzorno, ND Chair, Scientific Advisory Board
Bioclinic Naturals POB 25801
Seattle, WA 98165-1301
p: (206) 368-5403
f: (206) 368-8570
mail2@drpizzorno.com


RE: Are There Dietary Options for Cancer Prevention? - henrywronger - 08-25-2012 10:11 AM

A remarkable elimination in cancer occurrence is achievable, given major variations in lifestyle and upgrades in ecological situations. Most cancer avoidance techniques, regrettably are specific at the level of early prognosis rather than actual prevention. Although detection of cancers through acceptable tests such as clinical exam colonoscopy etc.