Pomegranates are put to the test for weight loss, diabetes, COPD, prostate cancer, osteoarthritis, and rheumatoid arthritis.
The case of POM Wonderful (the pomegranate juice company) vs. Federal Trade Commission made it all the way up to the U.S. Court of Appeals before being denied review by the Supreme Court. In that landmark case, a panel of judges concluded that many of POM’s ads made false or misleading claims and the company “touted medical studies ostensibly showing that daily consumption of its products could treat, prevent, or reduce the risk of various ailments, including heart disease, prostate cancer, and erectile dysfunction.” The U.S. First Amendment does not protect misleading and deceptive ads. Striking a blow to its billionaire owners, the Court ruled that at least one randomized clinical trial would be required to substantiate claims of treating or preventing disease.
If you look at the medical literature on pomegranate in general, you’ll see reviews touting its many benefits, with diagrams like the one below on the medicinal effects of pomegranates (which you can also see at 1:01 in my video Pomegranate: A Natural Treatment for Rheumatoid Arthritis).
But if you dig a little deeper, you see this is based on studies like one that talks about the “antiobesity effects of pomegranate leaf extract in a mouse model.” First of all, who eats pomegranate leaves? And second, who’s a mouse?
Does pomegranate consumption affect weight in humans? If you look at all the randomized controlled clinical trials (meaning human trials), pomegranates have no significant effect on body weight, BMI, belly fat, or even body fat percentage in those randomized to consume pomegranate products. What about the prevention and treatment of cardiovascular diseases? Researchers reviewed 25 clinical trials, looking at cholesterol, blood pressure, artery function, atherosclerotic plaque formation, and platelet function, and did not find significant indications of benefit even in the best studies.
POM Wonderful helped fund a study on pomegranate juice and erectile dysfunction, but it failed as well. Other studies found no benefit for diabetes markers and observed no benefit for chronic obstructive pulmonary diseases, such as emphysema. They were banking on the antioxidant activity of pomegranate juice to help, but that’s antioxidant activity in vitro (meaning in a test tube or petri dish). To my surprise, a meta-analysis of data from 11 randomized controlled trials “did not support convincing evidence” of pomegranate intake having a significant effect on increasing the total antioxidant capacity in the bloodstream because some of the most potent antioxidants don’t even seem to be absorbed into the human body. No wonder pomegranate supplementation didn’t seem to affect oxidative stress in tissue samples taken from prostate cancer patients. But, of course, what we care about is whether it affects the cancer itself.
The strongest evidence for the anticancer activity of pomegranates is said to come from studies on prostate cancer. Unfortunately, early promising results were not confirmed when they were actually put to the test. For example, daily pomegranate intake was found in a randomized controlled trial to have no impact on PSA levels, a marker of tumor progression. Additionally, a randomized, double-blind, placebo-controlled trial found essentially no difference when it came to prostate cancer disease progression, as you can see below and at 3:19 in my video.
They were banking on the anti-inflammatory activity of pomegranate juice to help, but again, that had been demonstrated in vitro. In people, a meta-analysis based on five randomized controlled trials published in 2016 concluded that pomegranate juice did not have a significant effect on C-reactive protein levels, a key marker of inflammation. If you look at the forest plot, though, you’ll see all five trials tended towards lower C-reactive protein levels such that the data combined almost reached statistical significance, as you can see below and at 3:53 in my video.
Indeed, an updated meta-analysis published in 2020 based on seven studies crossed the threshold into statistical significance and found a significant drop in two other inflammatory markers as well.
Perhaps pomegranate juice could help in the control of inflammatory diseases after all. But you don’t know until you put it to the test.
Osteoarthritis involves the degeneration of the cushioning cartilage within joints, particularly the knees. Dripping a pomegranate extract on human osteoarthritic cartilage samples appears to show cartilage-protective effects. As you can see below and at 4:43 in my video, compared to baseline levels of cartilage disintegration, adding inflammation triples the damage. However, with increasing amounts of pomegranate extract, the breakdown starts to calm down.
But again, that’s in a petri dish. How do we know that when we eat pomegranates, the active components actually get into our bloodstream so they can find their way into our joints? Cartilage-protecting components were found to be bioavailable (at least in rabbits), raising the possibility that pomegranates could be a safe and non-toxic treatment with no side effects, as opposed to the drugs currently in use. But is it effective?
The first clinical trial on pomegranate juice and osteoarthritis was not a placebo-controlled trial, but instead randomized people to pomegranate juice or nothing at all. Those drinking the juice did report less stiffness and impairment of physical function, but not significantly better than just doing nothing. Shoot.
Just as I was about to give up on pomegranates, I saw a study titled “Consumption of Hydrolyzable Tannins-Rich Pomegranate Extract Suppresses Inflammation and Joint Damage in Rheumatoid Arthritis.” But it turned out to be from the POM “Not-So-Wonderful” company, inducing joint damage in a mouse as a model of rheumatoid arthritis. Come on!
There was an open-label study, where the patients knew what they were getting. Eight people with active rheumatoid arthritis took pomegranate extract every day, and the six who stuck with it reported fewer tender joints. But as we learned from the osteoarthritis study, if you don’t have a control group, you have no sense of what role, if any, the treatment actually plays.
Finally, we come to this randomized, double-blind, placebo-controlled trial. It’s about time! Half the study participants unknowingly got some pomegranate extracts; the other half unknowingly got the equivalent of a sugar pill. There appeared to be a significant improvement in the number of swollen joints, tender joints, pain intensity, a disease activity score, a health assessment questionnaire, and morning stiffness compared to placebo. So, if you have rheumatoid arthritis, I would indeed recommend you start eating pomegranates. Why not just pop pomegranate pills? After all, it was a pomegranate extract that alleviated disease activity. One good reason to stick to the fruit is that when 19 pomegranate supplements were tested in a laboratory, most didn’t actually appear to have any pomegranate in them at all! Only 6 out of 19 appeared to be authentic.
Doctor’s Note
I previously reported on POM Wonderful back in 2011 in my video Is Pomegranate Juice That Wonderful?. My other video on this fruit is Flashback Friday: Pomegranate vs. Placebo for Prostate Cancer.
What’s one way you can eat them? Check out my cooking video for Cran-Chocolate Pomegranate BROL Bowl.
