Cancer Prevention (Reducing the Risk)

Cancer happens when cells split without control or order. As more cells are made, they form a growth or tumor. This may harm nearby healthy cells and spread to other parts of the body.

The risk of some types of cancer can be lowered with habit changes, such as not smoking, eating fruits and veggies, keeping a healthy weight, exercising, and staying away from too much sun. Some people turn to natural therapies to further lower their risk.

Natural Therapies

Possibly Effective

  • Selenium is a mineral that is found in many foods. It has antioxidants. Selenium pills may lower the risk of gastrointestinal (GI) cancers.A5, A7, A10, A18
  • Soy —may be a link between eating a lot of soy and a lower risk of breast, prostate, and lung cancer.B1, B5, B9- B12

Possibly Not Effective

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Herbs and Supplements to Be Used With Caution

Talk to your doctor about any natural therapy you are taking to make sure it does not get in the way of your treatment.

  • Calcium in large amounts can result in bone pain, lack of muscle strength, problems with focus, fatigue, and other health issues.
  • Selenium in large amounts can cause bad problems, such as hair and nail loss, GI and neurological issues, shaking, kidney and heart failure, and other problems.
  • Vitamin C raises iron absorption. Too much iron can be unsafe. Talk to your doctor if you also take iron in pill form. High vitamin C intake may also result in loose stools.
  • Beta-carotene and Vitamin E pills have been linked to a slight raised risk of death. Do not take it in high doses.


A. Supplements

A1. Lawson KA, Wright ME, et al. Multivitamin use and risk of prostate cancer in the National Institutes of Health –AARP Diet and Health Study. J Natl Cancer Inst. 2007 May 16;99(10):754-764.

A2. Lin J, Manson JE, et al. Intakes of calcium and vitamin D and breast cancer risk in women. Arch Intern Med. 2007 May 28;167(10):1050-1059.

A3. Lappe JM, Travers-Gustafson D, et al. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr. 2007 Jun;85(6):1586-1591.

A4. Bardia A, Tleyjeh IM, Cerhan JR, et al. Efficacy of antioxidant supplementation in reducing primary cancer incidence and mortality: systematic review and meta-analysis. Mayo Clin Proc. 2008;83:23-34.

A5. Bjelakovic G, Nikolova D, et al. Antioxidant supplements for preventing gastrointestinal cancers. Cochrane Database Syst Rev. 2008 Jul 16;(3):CD004183.

A6. Chlebowski RT, Johnson KC, Kooperberg C, et al. Calcium plus vitamin D supplementation and the risk of breast cancer. J Natl Cancer Inst. 2008;100:1581-1591.

A7. Peters U, Littman AJ, et al. Vitamin E and selenium supplementation and risk of prostate cancer in the vitamins and lifestyle (VITAL) study cohort. Cancer Causes Control. 2008 Feb;19(1):75-87.

A8. Wei MY, Garland CF, Gorham ED, et al. Vitamin D and prevention of colorectal adenoma: a meta-analysis. Cancer Epidemiol Biomarkers Prev. 2008;17:2958-2969.

A9. Gaziano JM, Glynn RJ, et al. Vitamins E and C in the prevention of prostate and total cancer in men: the Physicians’ Health Study II randomized controlled trial. JAMA. 2009 Jan 7;30(1):52-62.

A10. Lippman SM, Klein EA, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the selenium and Vitamin E cancer prevention trial (SELECT). JAMA. 2009 Jan 7;301(1):39-51.

A11. Figueiredo JC, Grau MV, et al. Folic acid and risk of prostate cancer: results from a randomized clinical trial. J Natl Cancer Inst. 2009 Mar 18;101(6):432-435.

A12. Myung SK, Ju W, Kim SC, Kim H; Korean Meta-analysis (KORMA) Study Group. Vitamin or antioxidant intake (or serum level) and risk of cervical neoplasm: a meta-analysis. BJOG. 2011;118(11):1285-1291.

A13. Stratton J, Godwin M. The effect of supplemental vitamins and minerals on the development of prostate cancer: a systematic review and meta-analysis. Fam Pract. 2011 Jun;28(3):243-252.

A14. Klein EA, Thompson IM Jr, et al. Vitamin E and the risk of prostate cancer: the selenium and vitamin E cancer prevention trial (SELECT). JAMA. 2011 Oct 12;306(14):1549-1556.

A15. Myung SK, Ju W, et al. Vitamin or antioxidant intake (or serum level) and risk of cervical neoplasm: a meta-analysis. RJOG. 2011 Oct;118(11):1285-1291.

A16. Ilix S, Doevwa KM, et al. Lycopene for the prevention of prostate cancer. Cochrane Database Syst Rev. 2011 Nov 9;(11):CD008007.

A17. Chung M, Lee J, et al. Vitamin D with or without calcium supplementation for prevention of cancer and fractures: an updated meta-analysis for the U.S. Preventive Services Task Force. Ann Intern Med. 2011 Dec 20;155(12):827-838.

A18. Hurst R, Hooper L, et al. Selenium and prostate cancer: systematic review and meta-analysis. Am J Clin Nutr. 2012 Jul;96(1):111-122.

A19. Boehm K, Borrelli F, Ernst E, Habacher G, Hung SK, Milazzo S, Horneber M. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database Syst Rev. 2009 Jul 8;(3):CD005004.

A20. Pais R, Dumitraşcu DL. Do antioxidants prevent colorectal cancer? A meta-analysis. Rom J Intern Med. 2013 Jul-Dec;51(3-4):152-63.

A21. Bjelakovic G, Gluud LL, et al. Vitamin D supplementation for prevention of cancer in adults. Cochrane Database Syst Rev. 2014 Jun 23;(6):CD007469.

A22. Wang R, Zheng Y, et al. Folate intake, serum folate levels, and prostate cancer risk: a meta-analysis of prospective studies. BMC Public Health. 2014 Dec 29;14:1326.

A23. Qin T, Du M, et al. Folic acid supplements and colorectal cancer: meta-analysis or randomized controlled trials. Sci Rep. 2015 Jul1;5:12044.

A24. Wang Y, Cui R, et al. Effect of carotene and lycopene on the risk of prostate cancer: a systematic review and dose-response meta-anlaysis of observational studies. PLoS One. 2015 Sep 15;10(9):e0137427.

A25. Baron JA, Barry EL, et al. A trial of calcium and vitamin D for the prevention of colorectal adenomas. N Engl J Med. 2015 Oct 15;373(16):1519-1530.

A26. Burr NE, Hull MA, et al. Folic acid supplementation may reduce colorectal cancer risk in patients with inflammatory bowel disease: a systemic review and meta-analysis. J Clin Gastroenterol. 2017 Mar;51(3):247-253.

B. Other Therapies

B1. Au AH, KoH WP, et al. Soy intake and breast cancer risk in Singapore Chinese Health Study. Br J Cancer. 2008 Jul 8;99(1):196-200.

B2. Liu J, Xing J, Fei Y. Green tea ( Camellia sinensis) and cancer prevention: a systematic review of randomized trials and epidemiological studies. Chin Med. 2008;3:12.

B3. Shimizu M, Fukutomi Y, Ninomiya M, et al. Green tea extracts for the prevention of metachronous colorectal adenomas: a pilot study. Cancer Epidemiol Biomarkers Prev. 2008;17:3020-3025.

B4. Myung SK, Bae WK, et al. Green tea consumption and risk of stomach cancer: a meta-analysis or epidemiologic studies. Int J Cancer. 2009 Feb 1;124(3):670-677.

B5. Yan L, Spitznagel EL. Soy consumption and prostate cancer risk in men: a revisit of a meta-analysis. Am J Clin Nutr. 2009 Apr;89(4):1155-1163.

B6. Ogunleye AA, Xue F, et al. Green tea consumption and breast cancer risk or recurrence: a meta-analysis. Breast Cancer Res Treat. 2010 Jan;119(2):477-484.

B7. Zheng J, Yang B, et al. Green tea and black tea consumption and prostate cancer risk: an exploratory meta-analysis of observational studies. Nutr Cancer. 2011;63(5):663-672.

B8. Yang G, Shu XO, et al. Soy food intake and risk of lung cancer: evidence from the Shanghai Women’s Health Study and a meta-analysis. Am J Epidemiol. 2012 Nov 15;176(10):846-855.

B9. Fritz H, Seely D, et al. Soy, red clover, and isoflavones and breast cancer: a systematic review. PLoS One. 2013 Nov 28;8(11):e81968.

B10. Van Die MD, Bone KM, et al. Soy and soy isoflavones in prostate cancer: a systematic review and meta-analysis of randomized controlled trials. BJU Int. 2014 May;113(5b):E119-30.

B11. Boehm K, Borrelli F, Ernst E, Habacher G, Hung SK, Milazzo S, Horneber M. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database Syst Rev. 2009 Jul 8;(3):CD005004.

Last reviewed March 2019 by EBSCO NAT Review Board Richard Glickman-Simon, MD
Last Updated: 3/27/2019

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