So drinking cranberry juice can lower your PSA level, but what does that mean?

As we have noted numerous times before, there are all sorts of things that can be done to lower one’s PSA level, but knowing whether these effects are clinically meaningful is a very different issue.

In a new paper just published by Student et al. (from a research team in the Czech Republic), the authors have shown that prostate cancer patients who were scheduled to undergo radical prostatectomy as a treatment for prostate cancer could lower their PSA levels by drinking cranberry juice (made by dissolving 1,500 mg of cranberry fruit powder) for 30 days prior to their surgery. But what does this actually mean?

Student et al. randomized 64 patients to drinking the cranberry juice or to drinking a placebo for an average of 30 days prior to their radical prostatectomy. Here is a summary of what they found:

  • Compared to the men taking the placebo, the men drinking the cranberry juice
    • Experienced a drop of 22.5 percent in their PSA levels prior to their surgery.
    • Exhibited “a trend to down-regulation” of urinary beta-microseminoprotein (MSMB) and serum gamma-glutamyltranspeptidase
    • Exhibited a trend to upregulation of IGF-1
    • Showed no changes in prostate tissue markers or in composition and concentration of phenolics in urine

The authors conclude that

Daily consumption of a powdered cranberry fruit lowered serum PSA in patients with prostate cancer. The whole fruit contains constituents that may regulate the expression of androgen-responsive genes.

However, there is no sign from these data that drinking cranberry juice actually made any clinical difference to the outcomes for these patients.

Of course drinking cranberry juice is unlikely to do you any significant harm, so if you like drinking it, go right ahead. In a previous paper the same group of authors say they have also shown that drinking cranberry juice can lower PSA levels in men who were biopsy negative for prostate cancer and for chronic non-bacterial prostatitis.

Of course if you have been drinking cranberry juice on a regular basis (whether you have prostate cancer or not), then  what is clear is that you and your doctors had better be aware that this can lower PSA levels. In other words, a man with a PSA level of 2.5 ng/ml who has been regularly drinking cranberry juice might have a “real” PSA level of more like 4.0 ng/ml, which might make it wise for him to realize that he is at risk for prostate cancer.

Now what might be interesting would be to see whether drinking cranberry juice might help men with low-risk prostate cancer to stay on active surveillance as opposed to having treatment they they don’t really need (because the cranberry juice might help to keep their PSA levels a little lower).

14 Responses

  1. If your PSA is indicative of prostate cancer, why in the world would a man try and hide the fact? Unless it also kills the cancer cells.

  2. When the PSA is over 20, is it correct to infer that it is due to abnormal activity/behavior of prostate cells?

    Then, if the PSA level drops significantly, due to whatever reason, is it correct to conclude that the abnormal behavior/activity of prostate cells is reduced?

    If so, what is the downside of trying nutritional approaches such as increased cranberry intake?

  3. I think what it means is that POM Wonderful will make claims that cranberry juice decreases PSA, and then add that PSA is an indicator of prostate cancer. We’ll have to see if the FDA lets them get away with it as long as they don’t make the claim explicitly that cranberry juice reduces prostate cancer.

  4. Dear PiperJohn2:

    It’s important to appreciate that PSA levels of less than about 50 ng/ml are never “indicative of prostate cancer” in a man who hasn’t already been diagnosed with prostate cancer. At best they are indicative of risk for prostate cancer (and several other possible prostate disorders).

  5. Dear Sushil:

    (1) No. It is not correct to presume that if a PSA level is > 20 that it is due to “abnormal” activity or behavior of prostate cells. A “normal” PSA level in any man is usually between about 0.5 and 4.0 ng/ml depending on his age and the volume of his prostate.

    (2) No. It is not correct to assume that a significant drop in a man’s PSA level “due to whatever reason” is because there has been a reduction in the abnormal behavior/activity of the prostate cells. All we know when a PSA level drops like that is that there is less PSA in the patient’s bloodstream.

    (3) Consequently, having a lower PSA level after it has risen to an elevated level is not necessarily indicative of a change in the underlying problem. For example, certain drugs (e.g., finasteride and dutasteride) can shrink the prostate, thus treating benign prostatic hyperplasia, but when you shrink the prostate like this you lower PSA levels, which can lead to men with prostate cancer showing no signs of risk for prostate cancer, and therefore not getting diagnosed when appropriate. The same (or something similar) may well be the case as a consequence of using nutritional products.

  6. Sorry, my cynical comment was directed at the makers of cranberry juice this time, rather than pomegranate juice.

  7. Dear Allen:

    The FDA has no authority over any advertising claim made by the nutritional/supplements industry (or any of its wonderful representatives) so long as they don’t make a claim of clinical effectiveness in the treatment or prevention of disease.

  8. Right. That’s why they made POM Wonderful stop making such claims for pomegranate juice. What I’m wondering is if the FDA will argue that a claim is implied when a manufacturer leaves out the key information that lowering PSA does not lead to lower risk of prostate cancer — a sin of omission. I’m sure lawyers will make money on this, no matter what. (I seem to be very cynical this week — you can probably guess why.)

  9. Upregulation of IGF-1. Isn’t that the real story here?

    Epidemiological studies have established a link between high circulating serum IGF-1 levels and the risk of later developing advanced prostate cancer, and overexpression of IGF-1 in the prostate basal epithelial layer of transgenic mice results in prostate adenocarcinoma that is similar to human disease.

    There’s a counter-intuitive linkage here …

  10. Kurt,

    One has to approach such genetic markers with caution. Yes, IGF-1 has been implicated in mouse models, yet IGF-1 blocking has not been shown to provide any clinical benefit (figitumumab and cixutumumab). On the other hand, MSMB, which was downregulated in this study, has shown some potential usefulness as a prognostic marker. None of this is especially interesting — lots of things upregulate and downregulate genes without any clinical significance. Genetics of cancer progression is unimaginably complex, so it takes more than isolated effects on a few genes to determine whether any effect is clinically meaningful.

  11. What would really interest me would be a follow-up study of these men after they had the surgery.

    Were there any significant differences between the 2 groups regarding post-surgical outcomes?

    Furthermore, for those individuals who showed a biochemical failure after surgery, would their PSAs go down after a regimen of “cranberry juice therapy”?

  12. Dear pfadtag:

    I have a very hard time believing that these patients would have had any difference in their surgical outcomes based on drinking cranberry juice. And the only way you would be able to tell that would be through a very large, randomized, placebo-controlled clinical trial that would require several hundred patients at least.

    If a patient had a biochemical recurrence after surgery (whether he had been drinking cranberry juice or not before the surgery) I also have a very hard time thinking that anyone would just want to give him cranberry juice after the biochemical recurrence. This is a patient who would then already be at potential risk for metastatic prostate cancer. Giving him cranberry juice to see if it lowered his PSA level would simply give the cancer more time to metastasize before anything was actually done about the risk for metastasis.

  13. Cut and paste fhis URL ( into a browser, or do a search for Consumer Labs to dig out this info.

    Interesting input. As usual, much depends on your openness to supplements and trust in the researcher. You’ll need to cut and paste this URL.

    I am a long-term member of Consumer Labs and trust their work. Consider joining them. I am just one of their members.

  14. Dear Bruce:

    No one is arguing about the fact that drinking cranberry juice can lower PSA levels in at least some men (whatever the reason is that the PSA level is elevated). The problem is that lowering PSA levels without addressing the fundamental problem could present an even greater problem — particularly if the reason the PSA level has risen is because of prostate cancer. You may just end up “masking” the real problem.

    If you lower PSA levels in a man who has prostate cancer, it doesn’t mean the cancer has gone away. It just means that you have a lower PSA level while the cancer continues to grow.

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