Pomegranate Juice and Prostate Health

Diet, Habits, & Other Behaviors, Prostate Cancer, Prostate Cancer
Laura Covarrubias, Cancer Prevention and Treatment Fund

Pomegranate juice contains plenty of antioxidants, but does it improve health, as the ads imply? Pom Wonderful, a large company that makes pomegranate juice and other products from pomegranates, would like you to believe that the juice can prevent or treat a number of health problems, including prostate cancer and erectile dysfunction. However, a close look at the science behind these claims shows that drinking pomegranate juice to treat or prevent prostate cancer and erectile dysfunction might not be worth the cost or the calories.

Prostate cancer is the most common cancer among men, other than skin cancer. (For more on skin cancer, read Tanning Beds: Safe Alternative to Sun? and Running and Skin Cancer Prevention.) Since almost everyone knows someone with prostate cancer, and since treatments can cause erectile dysfunction and incontinence, there is a tremendous desire to find a way to prevent the disease.

Even among men who have not had prostate cancer, erectile dysfunction-the inability to have or maintain an erection (called “ED” in advertisements)-is common. Many men suffering from erectile dysfunction want treatments that are less expensive and more natural than Viagra and other prescription medications.

Drinking pomegranate juice has been touted as an easy solution to decreasing the risk of prostate cancer and improving erectile dysfunction, but does it work? Nearly all of the studies are sponsored by Pom Wonderful, which is selling the products that the studies are evaluating. The company reports having spent at least $35 million on the research; unfortunately, studies sponsored by a product’s manufacturer tend to be biased in favor of the products.[1]

A May 2012 ruling by the Federal Trade Commission (FTC) concluded that Pom Wonderful’s promotional materials about the health benefits of their products are misleading and that their claims that pomegranate juice can treat, prevent, or reduce the risk of certain health conditions (including prostate cancer, erectile dysfunction, and heart disease) were deceptive.[2] Because of federal laws against making misleading disease prevention and treatment claims, the court issued a cease-and-desist order to Pom Wonderful. While the ruling prohibits Pom Wonderful from promoting its juice as a treatment for prostate cancer or erectile dysfunction, it doesn’t prevent the company from making broad claims about pomegranate juice such as that it “promotes prostate health.”

What the Science Says about Prostate Cancer and Pomegranate Juice

Only one study has been published in a peer-reviewed medical journal that looks at the effect of drinking pomegranate juice on prostate cancer. This 2006 study, funded by Pom Wonderful, is often used by the company to back its claims that their juice can help fight prostate cancer.[3] Only 46 men treated with either surgery or radiation for prostate cancer participated. All the men had rising prostate-specific antigen (PSA) levels, which is interpreted as a sign that their prostate cancer had come back, and all were given 8 ounces of Pom Wonderful to drink daily for a period of two years. The study found that the men’s rising PSA levels slowed, which can mean that their cancers were no longer growing as fast. To read more about PSA tests, click here.

In most scientific research, some patients receive a new treatment and the others receive either a placebo (sugar pill) or an older treatment. The Pom study was poorly designed because all the men drank the juice, making it impossible to evaluate the impact of the juice. Since PSA levels vary over time, we can’t know if PSA levels dropped because of the juice or would have dropped even without the juice.  In addition, the study only evaluated 46 men, all of whom had been treated for prostate cancer.  This small number of prostate cancer patients is not large enough to draw conclusions about all men, or even all men who have been treated for prostate cancer.

This 2006 study also looked at samples of cancer cells that were taken from other men with prostate cancer-not the same men who drank the pomegranate juice. These cancer cells were then treated with serum – a component of blood – from the men who drank pomegranate juice to see if the cancer cells stopped growing. The study found that cancer cells died when treated with the serum.  That sounds impressive, but there are many reasons why the serum could have caused the cancer cells to die. The researchers called for a future study with a control group (where cancer cells are treated with nothing), but six years later no study like that has been published.

Studies of pomegranate juice on mice and on human cells were more promising, but also not conclusive. One study funded by the U.S. Public Health Service, a government agency, looked at the effect of pomegranate extract – a very concentrated form of pomegranate juice – on prostate cancer cells that were taken from patients but grown outside of the body.[4] They found that the growth of cancer cells treated with the pomegranate extract was slower in comparison to the cancer cells not treated with the extract. In this same study, scientists also looked at the effects of pomegranate extract on the tumor size of mice with prostate cancer. They saw that the growth rate of the tumors in mice treated with the extract was slower in comparison to the growth rate of tumors in the mice that were not treated.

Another laboratory study found that more prostate cancer cells died in the samples treated with pomegranate juice concentrate provided by Pom Wonderful than in samples treated with different types of pomegranate extract.[5] The researchers believe that the many different chemical compounds in pomegranate juice work together to kill cancer cells, and that the pomegranate extract did not have all of these compounds and so did not have as strong of an effect. However, this study does not tell us if drinking pomegranate juice-rather than applying it to cancer cells-can prevent or treat cancer.  Even if there were research indicating a benefit from drinking the juice, how much juice would men have to drink?

Pom has also funded studies on clogged arteries and diabetes, which required people to drink 8 ounces of pomegranate juice every day (these studies were also inconclusive about the effects of pomegranate juice).[6,7] Even if 8 ounces a day was effective at lowering prostate cancer risk or improving health, this is a solution that not everyone could afford.  The cost of the juice, which would not be covered by health insurance, would be about $780 a month.[8] Drinking 8 ounces of Pom Wonderful adds an additional 160 calories per day, which equals 1,120 calories a week and 4,800 calories a month.  Unless the juice replaces an equally caloric drink, this could increase a person’s weight, which in turn increases the risk of prostate cancer and several other types of cancer (Weight and Cancer: The Latest Research).

What other alternatives are there?  Diets high in fiber and low in meat products and saturated fats have been linked to a lower risk of prostate cancer in men, and these diets also have other positive health effects such as reducing the risk of developing diabetes, heart disease, and stroke.[9,10,11] To learn more about the connections between diet and prostate cancer, read here.

What the Science Says about Erectile Dysfunction and Pomegranate Juice

There is even less evidence behind Pom Wonderful’s claims that drinking pomegranate juice decreases erectile dysfunction than there is about prostate cancer or other illnesses. Two studies used by Pom Wonderful to back these claims were conducted on rabbits – not humans.[12,13]These studies found that antioxidants (not pomegranate juice specifically) may be useful against erectile dysfunction, although no definite conclusions were made even for rabbits, and certainly not for humans.

The only study of humans used by Pom Wonderful divided the 53 participants with erectile dysfunction into two groups.[14] One group was assigned to drink pomegranate juice every day for the first 28 days, while the other group drank a placebo drink. After 28 days, the men answered questions about their erectile function. For the next two weeks, both groups stopped drinking their assigned drink (juice or placebo) – this time is known as a “washout” period. Research studies use washout periods to make sure that any effects of the treatment do not continue to be measured when the person begins drinking the new drink. After the washout period, the groups switched drinks so that the group that drank pomegranate juice drank the placebo for 28 days (and vice versa). Again, the men answered the same questions about their erectile function. Overall, the researchers did not find any statistically significant difference between the two groups.  Although there was a slight decrease in erectile dysfunction among the men drinking the pomegranate juice, the difference was small and could have occurred by chance. The researchers called for a larger and longer study to determine if pomegranate juice really does improve erectile dysfunction. We agree.

More Research Needed

Better research on men is needed to determine if regularly drinking pomegranate juice or taking pomegranate extract pills prevents or helps treat prostate cancer, erectile dysfunction, or other conditions. In the meantime, there is no harm in drinking pomegranate juice as long as it does not contribute to overweight or obesity.  Men who choose to drink pomegranate juice should consider the extra calories and cost.

Bottom Line:

  • There is no strong evidence to support the claim that pomegranate juice protects against prostate cancer or helps with erectile dysfunction.
  • Age increases the likelihood of prostate cancer and erectile dysfunction, and weight gain can also increase the chances of getting prostate cancer or having it return after treatment.[15]
  • If you or a loved one is undergoing treatment for prostate cancer, pomegranate juice is not an effective alternative.

References:

  1. Lexchin J, Bero L, Djulbegovic B. Pharmaceutical industry sponsorship and research outcome and quality: systematic review. Bmj. 2003;326(May). Available at: http://www.bmj.com/content/326/7400/1167.short. Accessed June 6, 2012.
  2. United States of America Federal Trade Commission. Initial Decision. 2012. Available at: http://www.ncbi.nlm.nih.gov/pubmed/1245105.
  3. Pantuck AJ, Leppert JT, Zomorodian N, et al. Phase II study of pomegranate juice for men with rising prostate-specific antigen following surgery or radiation for prostate cancer. Clinical cancer research : an official journal of the American Association for Cancer Research. 2006;12(13):4018-26. Available at: http://www.ncbi.nlm.nih.gov/pubmed/16818701. Accessed March 28, 2012.
  4. Malik A, Afaq F, Sarfaraz S, et al. Pomegranate fruit juice for chemoprevention and chemotherapy of prostate cancer. Proceedings of the National Academy of Sciences of the United States of America. 2005;102(41):14813-8. Available at: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1253570&tool=pmcentrez&rendertype=abstract.
  5. Seeram NP, Adams LS, Henning SM, et al. In vitro antiproliferative, apoptotic and antioxidant activities of punicalagin, ellagic acid and a total pomegranate tannin extract are enhanced in combination with other polyphenols as found in pomegranate juice. The Journal of nutritional biochemistry. 2005;16(6):360-7. Available at: http://www.ncbi.nlm.nih.gov/pubmed/15936648. Accessed May 24, 2012.
  6. Aviram M, Rosenblat M, Gaitini D, et al. Pomegranate juice consumption for 3 years by patients with carotid artery stenosis reduces common carotid intima-media thickness, blood pressure and LDL oxidation. Clinical nutrition (Edinburgh, Scotland). 2004;23(3):423-33. Available at: http://www.ncbi.nlm.nih.gov/pubmed/15158307. Accessed May 2, 2012.
  7. Rosenblat M, Hayek T, Aviram M. Anti-oxidative effects of pomegranate juice (PJ) consumption by diabetic patients on serum and on macrophages. Atherosclerosis. 2006;187(2):363-71. Available at: http://www.ncbi.nlm.nih.gov/pubmed/16226266. Accessed May 13, 2012.
  8. United States of America Federal Trade Commission. Initial Decision. 2012. Available at: http://www.ncbi.nlm.nih.gov/pubmed/1245105.
  9. Cohen JH, Kristal a R, Stanford JL. Fruit and vegetable intakes and prostate cancer risk. Journal of the National Cancer Institute. 2000;92(1):61-8. Available at: http://www.ncbi.nlm.nih.gov/pubmed/10620635.
  10. Ma RW-L, Chapman K. A systematic review of the effect of diet in prostate cancer prevention and treatment. Journal of human nutrition and dietetics : the official journal of the British Dietetic Association. 2009;22(3):187-99; quiz 200-2. Available at: http://www.ncbi.nlm.nih.gov/pubmed/19344379. Accessed June 10, 2012.
  11. Anderson JW, Baird P, Davis RH, et al. Health benefits of dietary fiber. Nutrition reviews. 2009;67(4):188-205. Available at: http://www.ncbi.nlm.nih.gov/pubmed/19335713. Accessed March 3, 2012.
  12. Azadzoi KM, Schulman RN, Aviram M, Siroky MB. Oxidative stress in arteriogenic erectile dysfunction: prophylactic role of antioxidants. The Journal of urology. 2005;174(1):386-93. Available at: http://www.ncbi.nlm.nih.gov/pubmed/15947695. Accessed July 16, 2012.
  13. Zhang Q, Radisavljevic ZM, Siroky MB, Azadzoi KM. Dietary antioxidants improve arteriogenic erectile dysfunction. International journal of andrology. 2011;34(3):225-35. Available at: http://www.ncbi.nlm.nih.gov/pubmed/20584092. Accessed July 16, 2012.
  14. Forest CP, Padma-Nathan H, Liker HR. Efficacy and safety of pomegranate juice on improvement of erectile dysfunction in male patients with mild to moderate erectile dysfunction: a randomized, placebo-controlled, double-blind, crossover study. International journal of impotence research. 2007;19(6):564-7. Available at: http://www.ncbi.nlm.nih.gov/pubmed/17568759. Accessed July 16, 2012.
  15. Kaluza J, Wolk A, Larsson SC. Red Meat Consumption and Risk of Stroke: A Meta-Analysis of Prospective Studies. Stroke; a journal of cerebral circulation. 2012. Available at: http://www.ncbi.nlm.nih.gov/pubmed/22851546. Accessed August 9, 2012.