Flashback Friday: Pomegranate vs. Placebo for Prostate Cancer

The pomegranate has been revered through the ages for its medicinal properties. So much so, it’s been used as a symbol for some medical organizations. A fruit seems to be a better representation of health than a snake on a stick.

Supposedly beneficial for a wide range of diseases. Even the cannibals love it, improving the color of “kid meat”—no, they’re talking about baby goats. It just made me double-take when I saw this study.

Most of the attention over the last decade has focused on pomegranates and prostate cancer. Starting with in vitro studies, showing more and more pomegranate extract can suppress the growth of prostate cancer cells in a petri dish by up to 95%.

Well, what about normal prostate cells? This is what normal prostate cells look like under a microscope, with a little or a lot of pomegranate extract. No real difference. Doesn’t seem to do much to healthy cells.

But, here’s what prostate cancer looks like; just decimated by the pomegranate. But, this was in a petri dish, not a person. Yes, if these results translated to the clinic, it could be dramatic. But first, we have to try it out in people.

Primary management of prostate cancer consists of either radical surgery, or radiation. Despite this, a significant number of patients relapse, and ultimately develop metastatic disease. Even after a radical prostatectomy, in about a third of the patients, the cancer comes back, as evidenced by rising PSA levels. At that point, the treatment options are limited—you already took out the prostate. The next step is essentially chemical castration; hormonal ablation. Just like breast cancer can thrive on estrogen, prostate cancer can thrive on testosterone. So, you can try to wipe out testosterone, but that can have such negative side effects. Anything we can do to delay that would be good. 

So, what about plants? They note that men in Asia have the lowest prostate cancer rates in the world: up to ten times less than North America. Now, is this just a genetic thing? No. When Japanese individuals move to the United States and start living and eating like us, their breast and prostate cancer rates shoot up right towards ours. This could be because of what they’re eating more of here; animal products are the strongest risk factor for prostate cancer worldwide, on a country by country basis.

Or, because of what they’re eating less of here—their traditional low-fat, high-fiber diets, with soy products, and green tea, and plant-rich in general. So, did these researchers try sticking these cancer patients on a plant-based diet? No. They just had them drink a cup of pomegranate juice every day. Why? Because the study was funded by the pomegranate juice folks. At least they were allowed to take it by mouth.

So, what happened? Well, in the three years leading up to the study, their cancer was steadily growing, as measured by their average PSA levels going up. Then, once they started the juice, their tumors continued to grow, but it looks like they were growing slower.

Now, in contrast, Dr. Dean Ornish and colleagues got an apparent reversal in early prostate cancer growth with a plant-based diet and other healthy lifestyle changes. PSA didn’t just go up slower; it trended down. And, dripping the blood of the men on prostate cancer growing in a lab, the blood serum of those eating healthy suppressed cancer growth nearly eight times better; whereas the blood of the men on the juice just suppressed cancer growth by about 12%. But still, to see anything, just drinking a cup of juice every day, is pretty impressive.

The problem is that there was no control group. Now, you could say they kind of acted as their own controls; this is them before, and after. It’s probably not just a coincidence that their tumors started growing slower right when they started the juice. But, check this out.

This is a drug trial trying to do the same thing—treat men with recurring prostate cancer after surgery or radiation. In the drug group, tumor growth slowed in 55% of the men. Pretty effective drug, right? The sugar pill worked 73% of the time. The placebo effect can be so powerful that it may slow cancer growth. This is why we need placebo-controlled trials. Maybe tricking people into drinking pomegranate-flavored Kool-Aid would have the same effect. You think you’re doing something for yourself, and so the cancer might slow.  You don’t know, until you put it to the test.

Finally, a randomized controlled trial of pomegranate juice for prostate cancer. And, as you can read in the title, it had no impact. What do they mean, no impact? 25% of the cancer patients appeared to shrink their tumors as soon as they started drinking the pomegranate juice. Yeah, but 35% shrunk their tumors not drinking pomegranate juice.

So, any effect appears to just be a placebo. It’s the same story with pomegranate extract pills. They seemed to work, until they went head to head with sugar pills, and fell flat on their face.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

• A Emami, M H Nasri, M Ganjkhanlou, A Zali, L Rashidi. Effects of dietary pomegranate seed pulp on oxidative stability of kid meat. Meat Sci. 2015 Jun;104:14-9.
• P Langley. Why a pomegranate? BMJ. 2000 Nov 4;321(7269):1153-4.
• S J Freedland, M Carducci, N Kroeger, A Partin, J Y Rao, Y Jin, S Kerkoutian, H Wu, Y Li, P Creel, K Mundy, R Gurganus, H Fedor, S A King, Y Zhang, D Heber, A J Pantuck. A double-blind, randomized, neoadjuvant study of the tissue effects of POMx pills in men with prostate cancer before radical prostatectomy. Cancer Prev Res (Phila). 2013 Oct;6(10):1120-7.
• A J Pantuck, J T Leppert, N Zomorodian, W Aronson, J Hong, R J Barnard, N Seeram, H Liker, H Wang, R Elashoff, D Heber, M Aviram, L Ignarro, A Belldegrun. Phase II study of pomegranate juice for men with rising prostate-specific antigen following surgery or radiation for prostate cancer. Clin Cancer Res. 2006 Jul 1;12(13):4018-26.
• M Albrecht, W Jiang, J Kumi-Diaka, E P Lansky, L M Gommersall, A Patel, R E Mansel, I Neeman, A A Geldof, M J Campbell. Pomegranate extracts potently suppress proliferation, xenograft growth, and invasion of human prostate cancer cells. J Med Food. 2004 Fall;7(3):274-83.
• C J Paller, X Ye, P J Wozniak, B K Gillespie, P R Sieber, R H Greengold, B R Stockton, B L Hertzman, M D Efros, R P Roper, H R Liker, M A Carducci. A randomized phase II study of pomegranate extract for men with rising PSA following initial therapy for localized prostate cancer. Prostate Cancer Prostatic Dis. 2013 Mar;16(1):50-5.
• M R Smith, J Manola, D S Kaufman, D George, W K Oh, E Mueller, S Slovin, B Spiegelman, E Small, P W Kantoff. Rosiglitazone versus placebo for men with prostate carcinoma and a rising serum prostate-specific antigen level after radical prostatectomy and/or radiation therapy. Cancer. 2004 Oct 1;101(7):1569-74.
• F Stenner-Liewen, H Liewen, R Cathomas, C Renner, U Petrausch, T Sulser, K Spanaus, H H Seifert, R T Strebel, A Knuth, P Samaras, M Müntener. Daily Pomegranate Intake Has No Impact on PSA Levels in Patients with Advanced Prostate Cancer - Results of a Phase IIb Randomized Controlled Trial. J Cancer. 2013 Aug 29;4(7):597-605.
• A Zarfeshany, S Asgary, S H Javanmard. Potent health effects of pomegranate. Adv Biomed Res. 2014 Mar 25;3:100.
• T Kimura. East meets West: ethnic differences in prostate cancer epidemiology between East Asians and Caucasians. Chin J Cancer. 2012 Sep;31(9):421-9.
• L N Kolonel, D Altshuler, B E Henderson. The multiethnic cohort study: exploring genes, lifestyle and cancer risk. Nat Rev Cancer. 2004 Jul;4(7):519-27.
• W B Grant. A multicountry ecologic study of risk and risk reduction factors for prostate cancer mortality. Eur Urol. 2004 Mar;45(3):271-9.
• Ornish D, Weidner G, Fair WR, Marlin R, Pettengill EB, Raisin CJ, Dunn-Emke S, Crutchfield L, Jacobs FN, Barnard RJ, Aronson WJ, McCormac P, McKnight DJ, Fein JD, Dnistrian AM, Weinstein J, Ngo TH, Mendell NR, Carroll PR. Intensive lifestyle changes may affect the progression of prostate cancer. J Urol. 2005 Sep;174(3):1065-9; discussion 1069-70.

Images thanks to PublicDomainPictures and edenirocha via Pixabay. Images have been modified.