Friends,
I liked Postop's post so well I'm repeating at the end of this post.
Still, we don't all need to be actuaries studied in the art of
- statistical significance and
- expected value of perfect information and
- marginal return on investment, etc.
to know that pomengranite juice has potassium and vitamin c and that in moderate quantities such things are good for you.
As a Fresh Produce Manager in a grocery store, I whole-heartedly recommend raw cruciferous vegetables at every opportunity without making any claims about studies that suggest
- a diet rich in cruciferous vegetables (servings, not supplements)
reduces the occurence of colon cancer.
While the rigorous scientific MDRs & RDAs for the most basic vitamins & minerals move around (e.g., folic acid RDA for pregnant women),
without any studies PERHAPS identifying lifesaving flavenoids and phytochemicals - I still recommend eating moderate meals of mostly fresh vegetables and fruits - even tart juices from concentrate if you count those sugars and brush and floss!
Risking a moderator editing this post for a sales pitch, consider:
Vitamin D from mushrooms - not megadoses of extracted IUs
Raw, cold milled flax seed - not expelled flax oil
Vitamin E from nuts - not a bottle....
and so forth.
Postop's call to a healthy skepticism and dynamically testing even the best research (BUYER BEWARE comes to mind) should be considered
while friends in a forum still support one another and
discuss (and perhaps qualify with a "maybe" or "I feel")
their (personal) views on articles of keen interest.
Which is better for you, kale or chard? Cauliflower or broccoli? Collards or cabbage? 
Full disclosure: I sell all six ......
Sincerely,
CEDAR
POSTOP WROTE 19FEB2011
I would give a different view of the scientific process. The scientific method is to propose an idea, and then test it. Debate is a side effect of the scientific method, but debate is just noise. What matters is testing the idea. For clinical trials, it is easy to do inadequate studies, hard to do definitive ones. An example is estrogen replacement therapy for women after menopause. If you do a search, there are thousands and thousands of studies that say it is a good thing. However, a few years back, a definitive study was done--after decades of routine use of HRT, and it showed that HRT for women was harmful. So now, very few women are put on it. One apparent result has been a sharp decline in breast cancer.
A definitive clinical study is randomized, double blind, placebo controlled. That's called level one evidence, because if the study is done right, with adequate number of patients, and you see a significant difference, you know that the treatment caused it, and that it's not due to other factor that you haven't controlled for. For example, in the study in this thread, PSA doubling time on two different doses of Pomagranate was compared to the doubling time before treatment was started. How do you know that the PSA doubling time wouldn't go down if you do nothing? So this study is not definitive proof.
Why be skeptical? Because there is a long history of treatments--not just nutritional suppliments, but all kinds of other things--that were once given to people all the time, that are now know not to work. Without the scientific method, doctors would be treating prostate cancer with leeches and blood letting.
You might say that supplements are harmless, and probably good for you. You may be right, but there are some supplements that turned out to be be bad for you, like high doses of vitamin E. If you look at the track record of nutritional treatments, very few have actually proven useful. There are many, many supplements that people used 10 or 20 years ago that have not panned out, and been abandoned. The odds are pretty poor.
In any case, doing something to yourself is your own business. To advocate that other people do it, you should have evidence. To claim that there is good evidence when there really isn't, well, that's just not right.
If you think pomagranate is a good thing, what you should do, is go to those guys that you admire that promote it, and demand that they spend money and carry out an adequate, definitive clinical trial to get level 1 evidence that it works. This is definitely doable. If they do that, we can stop talking about it, and either we all can take pomagranate, or we can all stop talking about it and move on to something else.