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The location of the prostate is one of nature's mistakes - like the organization of the eye, it argues against "intelligent design" which in any case was only a philosophical fart that fundamentalist Christianity had to release in order to adjust itself to the widespread acceptance of the evidence for evolution. Because it's ended up wrapped around the urethra for no good reason, it can easily disrupt the flow of urine if it swells for any reason, and, though they don't really tell you this, pissing is essential for life.
This essay on the prostate is limited to conditions and cures I have some experience of, and I'll add a bit about cancer at the end.
I first became aware of the prostate when I found myself unable to pee after a dose of opium, that is to say, after drinking a tea or slurry made from boiled up opium poppies. I ended up catheterized and being investigated in hospital. I suspected I was allergic in this way to the poppies (though this hadn't happened before) or a pesticide. A quick google search finds no case study of prostatitis - acute urinary retention is a side effect of opioids but also affects women.[1}
So it's likely the diagnosis of prostatitis I was given was wrong - or not - I continued having urinary retention on opiates but it was never impossible to overcome as it was on that occasion. Splashing cold water on my abdomen was probably the most effective strategy.
But then later in life I came across a different sort of problem, inadequate urination so that the bladder doesn't fully empty and you keep having to get up at night. This the doctor diagnosed as either prostatitis or benign prostatic hyperplasia (if it persisted I'd presumably get a biopsy to differentiate) and I set out to manage it myself.
The hyperplasia makes sense retrospectively because I know now that I was highly insulin resistant and hyperinsulinaemic in this days, I'd regularly suffer tinnitus after meals, glaucoma, and various other symptoms. The prostatitis also makes sense because I still had Hep C and various autoimmune complications (eg Sjorgen's syndrome) related to a high viral load.
I took all sorts of prostate supplements such as saw palmetto without relief. I did hit on one herbal formula that seemed to work, it contained forskolin and dead nettle, but was expensive and hard to find. What finally worked best was treating the UTI aspect - urine backed up in the bladder, especially if there's glucose in the urine, is going to be a breeding ground for bacteria. I discovered d-mannose, this was expensive but sort-of worked. And then I hit the jackpot - hibiscus flower. Cheap as chips from Middle Eastern food stores, a strong dose worked magic.
Around this time I was also going low-carb and staring to fix my hyperinsulinaemia and hep c related autoimmune issues.
How would hibiscus work? Its antioxidant phytochemical, the flavonoid or whatever that gives the flower its regal colour,, binds to surface proteins that UTI bacteria use to adhere to the wall of the bladder and urinary track where they can feast on passing nutrients. So you flush them out. And I think these bacteria irritate the prostate. Or maybe they just irritate the urethra and its mechanism for contracting or relaxing under will. PubMed says 
Chronic bacterial prostatitis is a subacute infection, may present with a variety of pelvic pain and voiding symptoms, and is characterized by recurrent urinary tract infections. Effective treatment may be difficult and requires prolonged antibiotic therapy.
So I think I'm right - a swollen prostate for any reason increases the risk of UTI, UTI increases the risk of swollen prostate, it's a vicious cycle and the UTI factor is easy to treat if you can find hibiscus flower (the dose in a tea bag is not enough), the overgrowth factor is easy to treat with a very low carb diet if you have hyperinsulinaemia (check the fasting TG/HDL ratio first as a good, cheap proxy for the 2-hour insulin level).
As for prostate cancer - it's said the risk of this is rising - I think there are 3 main factors - firstly, hyperinsulinaemia is a modern epidemic, it's a growth promoter and cancer promoter. Secondly, men are living longer and prostate cancer is something that's more likely to get you if you live long enough. Linus Pauling died of it at 93 and I think this can be considered a megadose vitamin C success story, especially considering he was a research chemist and had worked with carcinogens. Thirdly, diagnosis is more aggressive today and much prostate cancer is non-lethal or won't kill you faster than life will.
Low carb diets are a promising strategy for treating prostate cancer.
In Europe, where cheese and organ meats are significant sources of vitamin K2, vitamin K2 intake is strongly associated with a lower risk of prostate cancer.
The association was stronger for advanced prostate cancer (0.37; 0.16, 0.88; P for trend = 0.03).
That's a decent, Bradford Hill sized association - Vitamin K1 from plants had no association with risk.
ALA, the plant-based form of omega 3 fatty acid, is associated with increased prostate cancer risk.
epidemiologic studies also showed an increased risk of prostate cancer in men with a high intake or blood level of ALA (combined relative risk 1.70; 95% CI 1.12–2.58).
I suspect this is due to this fatty acid being highly valuable as a synthetic substrate for cancer cells; it's a highly ketogenic fatty acid but only in a keto context, otherwise this same property of interconvertability is less desirable.
Postscript - H/T Mike Angel who added this comment to the original post:
Here is the vulgarized version of the work being done in Israel: https://news.sky.com/story/prostate-treatment-gives-patients-new-hope-10486442 I think it's compelling. Apparently the idea came out of fertility treatments. This treatment is for testicular varicocele (I was screened for it at one stage) which is a mechanical cause of prostate hypertrophy and low testosterone (and probably the true, non-sexist cause of the "manspreading" phenomenon of a few years ago). A subject for another day perhaps.