Nutrition for Prostate Cancer Prevention

Prostate cancer is the most common type of cancer and the second leading cause of cancer death for 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 lifetimes. 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. 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.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 is associated with decreased risk of developing prostate cancer, to date there is very little hard evidence that demonstrates cause and effect.But here's a little bit more about the top five foods/nutrients that are associated with a decreased risk of prostate cancer:

• Calcium is the most common mineral in our body and plays important roles in bone density and strength as well as hormone, blood vessel, and muscle and nerve functions. The role of calcium in prostate cancer prevention, however, isn’t very clear, with some studies showing decreased risk with higher calcium intake while other studies show a possible increased risk with consuming more calcium. 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. Fat-free milk, unflavored milk substitutes like plain soy or almond milk that are fortified with calcium, and fat-free unsweetened yogurt are part of an overall healthful, balanced diet and are 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 rates 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. 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 fruits and vegetables their bright orange or red colors. 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. 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. However, the Prostate Cancer Prevention Trial followed over 18,000 men for 7 years and found no association between lycopene intake and developing prostate cancer. While consuming a variety of fruits and vegetables is part of a healthful, balanced diet, it’s not yet determined if routinely eating foods high in lycopene decreases the risk of prostate cancer.
• 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. 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. 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 thought to have 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. 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. 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.

Here's our take on the current research:Regularly choosing foods that are associated with a decreased risk of prostate cancer as part of an overall healthful and well-balanced diet may provide some benefit, and all of these foods also contain a variety of nutrients important for good health. Use these ideas to inform your weekly food choices:

• Replace chicken or red meat with tofu or tempeh in 2-3 meals per week. Make a quick stir-fry with a variety of vegetables and cubes of marinated tofu, or grill seasoned tempeh instead of pork chops.
• Enjoy unsweetened green tea as part of your daily beverages.
• Use miso paste, made from fermented soybeans, as part of salad dressings, soups, glazes, and marinades.
• Serve plain yogurt with a variety of fresh fruit, including deep-red or bright orange fruit such as grapefruit, papaya, and guava for breakfast.
• Whip up a smoothie for breakfast or a snack using plain yogurt or smooth tofu and a variety of fresh or frozen fruit.
• Cooking tomatoes increases the availability of lycopene. Toss whole wheat pasta with tomato sauce or make a vegetable ratatouille that contains tomatoes.
• Use plain Greek-style yogurt instead of mayonnaise in potato salad or pasta salad.
• Toss grapefruit or pomegranate seeds into a vegetable salad for a sweet flavor without added sugar.

By Lynn Grieger, RDN, CDE, CPT, CHWCReferences

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 7-1-18
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 7-1-18.
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. Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/ updated March 2, 2017. Accessed 7-1-18.
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6. 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.
7. 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.
8. 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.
9. 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.

PDF Handout: Prostate Cancer Prevention Handout