Nutrition

Food Choices and Risk of Prostate Cancer

Last updated: Jul 01, 2018

Prostate cancer is the most common type of cancer and the second leading cause of cancer death affecting men in the United States. Between 2011 and 2015, the median age of prostate cancer diagnosis was 66, and there were 112.6 cases of prostate cancer per 100,000 men per year. Based on this data, it’s estimated that approximately 11% of men will be diagnosed with prostate cancer in their lifetime.1 According to the National Cancer Institute, many men, especially those with a family history of prostate cancer, are interested in how they might prevent the diagnosis of prostate cancer with food choices and/or supplements.2 A survey of 542 men with at least one brother diagnosed with prostate cancer found that almost 60% used vitamins or supplements to try and prevent prostate cancer.3

A May 2018 report from the National Cancer Institute details the scientific research around foods and supplements commonly believed to prevent prostate cancer. While there is often epidemiological evidence that eating more of certain foods or minerals is associated with decreased risk of developing prostate cancer, to date there is very little hard evidence that demonstrates cause and effect.2

Read more about eight foods/nutrients that are associated with decreased risk of prostate cancer:

Calcium is the most common mineral in our body, stored in bones and teeth. Calcium plays an important role in bone density and strength as well as hormone, blood vessel, muscle and nerve functions. Dairy products and dairy substitutes fortified with calcium such as soy, rice, and almond milk provide the most calcium in our diet. Some types of fruit juice, breakfast cereals, and granola bars/energy bars contain added calcium. There is no clear association between calcium intake and risk of developing prostate cancer, with some studies showing a possible decrease in risk with more calcium intake, or a possible increase in risk with higher calcium intake, or no association at all.4 The Recommended Dietary Allowance for calcium for healthy males age 19-70 years is 1000mg, with 1200mg recommended for males over age 70, which is equivalent to 3-4 cups of milk or yogurt each day. Results from observational studies suggest that regularly consuming <1500-2000mg of calcium may be associated with increased prostate cancer risk, although additional research is necessary to understand more about this possible association.5 Fat-free milk, unflavored milk substitutes, and fat-free unsweetened yogurt are part of an overall healthy, balanced diet and good sources of calcium.

Green tea is a favorite beverage in many Asian countries, and countries where people drink more green tea have the lowest rate of prostate cancer in the world. Green tea contains a group of polyphenols called catechins that act as antioxidants in our body. Epigallocatechin-3-gallate (EGCG)is the most common catechin in green tea and has been associated with decreased risk of prostate cancer. Studies have shown that EGCG suppresses the production of prostate-specific antigen (PSA) and prostate cancer cell growth. Green tea as a beverage is usually well-tolerated, although some people may be sensitive to the caffeine content. EGCG is available as a supplement and has been shown to be safe at doses of 600mg to 1000mg per day for up to 1 year although some people report nausea, abdominal pain, vomiting, or flatulence. However, there are some reports of liver toxicity, primarily in women, who took EGCG supplements for weight loss.6 Always discuss any potential benefits of EGCG supplements with your physician. Drinking unsweetened green tea is a healthy beverage option; choose decaffeinated green tea if you want to avoid caffeine.

Lycopene is a phytochemical that gives various fruit and vegetables their bright orange or red color. Tomatoes, apricots, guavas, papaya, grapefruit and watermelon are especially high in lycopene. In laboratory studies lycopene has been shown to reduce prostate cancer cell proliferation, and animal studies show that lycopene may help prevent prostate cancer.7 However, the results from human trials with lycopene are inconsistent. Epidemiological studies show an association between men with a higher intake of lycopene from foods and a lower risk of prostate cancer and some studies have shown that men with prostate cancer have lower levels of lycopene in their bodies.8 The Prostate Cancer Prevention Trial followed over 18,000 men for 7 years and found no association between lycopene intake and developing prostate cancer.9 Lycopene absorption is increased when consumed with fat, such as adding olive oil to meals with cooked tomatoes.10 Consuming a variety of fruits and vegetables is part of a healthy, balanced diet.

Selenium is a mineral that is found in many proteins in the body that play important roles in reproduction and immunity. Selenium is also found in an enzyme that acts as an antioxidant to protect our cells from damage; however high levels of selenium may have the opposite effect and increase risk of some types of cancer.11 Food sources of selenium include seafood, meat, poultry, whole grains, eggs and dairy products. Brazil nuts contain very high amounts of selenium with 6-8 Brazil nuts containing 777% of the Daily Value of selenium.12 Some population studies show that men with higher blood levels of selenium haver lower risk of developing prostate cancer, while other studies show an increased risk. Clinical trials using selenium supplements are also mixed. Because there is no clear benefit of selenium in decreasing risk of prostate cancer, and there is the potential for an increased risk of cancer, it’s recommended that men avoid taking selenium supplements at doses higher than the RDA of 55 µg/day.11 Including foods high in selenium in your daily food choices such as whole grains, seafood and eggs provides a wide range of essential nutrients.

Numerous studies have shown that prostate cancer incidence is very low in Asian countries, where diets tend to be high in soy foods such as tofu, tempeh, miso and soy milk.13 Soy foods contain a variety of phytochemicals that may play a role in prostate cancer prevention. Isoflavones, including genistein, daidzein, and glycitein are among the most widely researched phytochemicals in soy foods and have been shown to affect the growth and spread of prostate cancer cells.14 One small study with 23 men showed that consuming two daily servings of soy foods for 3 months lowered PSA levels.15 However, the limited human research so far has not consistently shown reduced risk of developing prostate cancer by consuming soy foods or supplements.13 Soy foods are good sources of protein for people who follow a vegetarian or vegan eating pattern, and can be enjoyed by everyone as part of a meatless meal.

Pomegranate is a type of deep-red fruit native to much of Asia that has long been used for various medicinal properties. Pomegranate juice, arils (the small sacks of juice that surround each seed), and seeds contain minerals and several phenolic compounds that slow down the growth of prostate cancer cells in the lab, and rat studies have shown pomegranate juice can decrease the development, growth and spread of prostate cancer cells.16 Pomegranates  have strong antioxidant and anti-inflammatory effects, and some studies have suggested that they also may help protect against some types of cancer, including prostate cancer.17 Including pomegranate juice, seeds or arils as part of your daily food choices may help reduce risk of prostate cancer, although more human studies are needed.

Vitamin D is made in our body when sunlight interacts with cells in our skin and is also found in fatty fish such as salmon and tuna, as well as eggs. Vitamin D is added to most dairy and non-dairy products such as soy milk and almond milk. Numerous epidemiological studies have found a relationship between low blood levels of vitamin D and increased risk of developing prostate cancer.18 However, a meta-analysis published in 2011 reviewed 25 studies examining the link between prostate cancer incidence and indicators of vitamin D found no association between dietary vitamin D or circulating concentrations of vitamin D and risk of prostate cancer.19 Other studies have found increased risk of developing prostate cancer with higher blood levels of Vitamin D.18 Further research is needed to determine whether low intake of vitamin D increases cancer risk, whether higher vitamin D intake is protective, and whether some individuals could be at increased risk of cancer because of high vitamin D intake.10

Vitamin E is a fat-soluble vitamin that comes in eight different forms, with alpha-tocopherol the most abundant form in the body. Vitamin E is found in egg yolks, nuts, seeds, and vegetable oils such as canola, corn, sunflower and safflower oil. Because vitamin E acts as an antioxidant protecting cell membranes, it’s believed to play an important role in overall health.20 The Physicians’ Health Study II randomly assigned participants to 400 IU Vitamin E or 500mg Vitamin C per day for 8 years. The overall rate of prostate cancer was similar in both groups, suggesting that vitamin E has no effect on developing prostate cancer.21 The SELECT trial was designed to determine whether 7-12 years of daily supplementation with 400 IU vitamin E, with or without 200 mcg selenium, would reduce the development of prostate cancer in over 35,000 healthy men age 50 and older. The trial was discontinued in October 2008 when it was discovered that the supplements, either alone or together, did not prevent prostate cancer. Disturbingly, results from an additional 1.5 years of follow-up when participants no longer received vitamin E or selenium showed that the men who had taken vitamin E previously had a 17% increased risk of prostate cancer.22 Evidence to date is insufficient to support taking vitamin E to prevent cancer. In fact, daily use of large-dose vitamin E supplements (400 IU) may increase the risk of prostate cancer.23

Our take on the current research:

Regularly including foods that are associated with decreased risk of prostate cancer as part of an overall healthy and well-balanced diet may provide some benefit. However, the current research does not support taking supplements to prevent prostate cancer. Tips to include the beneficial foods:

  • Replace chicken or red meat with tofu or tempeh in 2-3 meals per week.
  • Enjoy unsweetened green tea as part of your daily beverages.
  • Serve plain yogurt with a variety of fresh fruit, including deep-red or bright orange fruit such as grapefruit, papaya, and guava for breakfast.
  • Cooking tomatoes increases the availability of lycopene. Toss whole wheat pasta with tomato sauce or make a vegetable ratatouille that contains tomatoes.
  • Include sunflower seeds in tuna salad, and replace mayonnaise with plain Greek-style yogurt for good sources of selenium, calcium, and vitamin D.

References

 

  1. National Institutes of Health. National Cancer Institute. Surveillance, Epidemiology, and End Results Program. Cancer Stat Facts: Prostate Cancer. https://seer.cancer.gov/statfacts/html/prost.html  Accessed 6-18-18
  2. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq  updated May 10, 2018. Accessed 6-18-18.
  3. Bauer CM, Ishak MB, Johnson EK, et al.: Prevalence and correlates of vitamin and supplement usage among men with a family history of prostate cancer. Integr Cancer Ther 11 (2): 83-9, 2012. 

  4. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). Calcium. https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq#section/_426  updated May 10, 2018. Accessed 6-18-18.
  5. National Institutes of Health. Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/ updated March 2, 2017. Accessed 6-18-18.
  6. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). Green Tea. https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq#section/_174 updated May 10, 2018. Accessed 6-19-18.
  7. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). Lycopene.  https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq#section/_16  last updated May 10, 2018. Accessed 6-19-18.
  8. Kavanaugh CJ, Trumbo PR, Ellwood KC: The U.S. Food and Drug Administration's evidence-based review for qualified health claims: tomatoes, lycopene, and cancer. J Natl Cancer Inst 99 (14): 1074-85, 2007.
  9. Kristal AR, Till C, Platz EA, et al. Serum Lycopene Concentration and Prostate Cancer Risk: Results from the Prostate Cancer Prevention Trial. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2011;20(4):638-646. doi:10.1158/1055-9965.EPI-10-1221.
  10. U.S. Food and Drug Administration. Summary of Qualified Health Claims Subject to Enforcement Discretion. https://www.fda.gov/Food/LabelingNutrition/ucm073992.htm#cancer last updated 2-15-2018. Accessed 6-20-18.
  11. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). Selenium. https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq#section/_283 updated May 10, 2018. Accessed 6-20-18.
  12. National Institutes of Health. Office of Dietary Supplements. Selenium Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/ last updated March 2, 2018. Accessed 6-20-18.
  13. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). Soy.  https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq#section/_163 last updated May 10, 2018. Accessed 6-20-18.
  14. Perabo FG, Von Löw EC, Ellinger J, et al.: Soy isoflavone genistein in prevention and treatment of prostate cancer. Prostate Cancer Prostatic Dis 11 (1): 6-12, 2008.
  15. Maskarinec G, Morimoto Y, Hebshi S, et al.: Serum prostate-specific antigen but not testosterone levels decrease in a randomized soy intervention among men. Eur J Clin Nutr 60 (12): 1423-9. 2006.
  16. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). Pomegranate.  https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq#link/_162  last updated May 10, 2018. Accessed 6-20-18.
  17. Wang L, Martins-Green M. Pomegranate and Its Components as Alternative Treatment for Prostate Cancer. International Journal of Molecular Sciences. 2014;15(9):14949-14966. doi:10.3390/ijms150914949.
  18. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). Vitamin D. https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq#link/_357 last updated May 10, 2018. Accessed 6-20-18.
  19. Gilbert R, Martin RM, Beynon R, et al.: Associations of circulating and dietary vitamin D with prostate cancer risk:  a systematic review and dose-response meta-analysis. Cancer Causes Control 22 (3): 319-40, 2011.
  20. National Institutes of Health. National Cancer Institute. Prostate Cancer, Nutrition and Dietary Supplements (PDQ®). Vitamin E. https://www.cancer.gov/about-cancer/treatment/cam/hp/prostate-supplements-pdq#link/_328 last updated May 10, 2018. Accessed 6-21-18.
  21. Gaziano JM, Glynn RJ, Christen WG, 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 301 (1): 52-62, 2009.
  22. National Institutes of Health. National Cancer Institute. Selenium and Vitamin C Cancer Prevention Trial (SELECT): Questions and Answers. https://www.cancer.gov/types/prostate/research/select-trial-results-qa updated July 7, 2015. Accessed 6-21-18.
  23. National Institutes of Health. Office of Dietary Supplements. Vitamin E Fact Sheet for Health Professionals.  https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/#en31 last updated March 2, 2018. Accessed 6-21-18.

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