Why the Aging Prostate Grows: Hormones Set the Stage, but Metabolism and Inflammation May Decide How Far It Goes
RapAdmin
This 2019 mini-review comes from urologists and prostate biologists in Vienna and Innsbruck. It summarizes what drives benign prostatic hyperplasia (BPH), the noncancerous growth of prostate tissue, and what it leads to clinically: an enlarged prostate and lower urinary tract symptoms. The authors focus mainly on the androgen pathway. Inside the prostate, testosterone is converted to the more potent dihydrotestosterone (DHT), which drives growth through the androgen receptor; finasteride and dutasteride block that conversion. They then survey newer contributors: the insulin-like growth factor (IGF) axis, estrogens, chronic inflammation, metabolic syndrome, obesity and genetics, and they briefly cover treatment. Several candidate interventions, including metformin, pomegranate extract and ginseng, have support only from rodent or cell studies.
By age 80, most men have benign prostatic hyperplasia, a slow, noncancerous overgrowth of the inner prostate. Many never notice it. Others get a weak stream, urgency and repeated trips to the bathroom at night. Even though BPH is so common, nobody can yet explain why one man ends up with a 40-gram prostate and another with a 200-gram one.
The authors start with the oldest and firmest piece of the puzzle: hormones. The testes make testosterone, and inside the prostate an enzyme called 5-alpha reductase converts it into dihydrotestosterone, or DHT, a far more potent androgen. Men castrated before puberty, and men born without a working form of the enzyme, do not develop enlarged prostates. This is why finasteride and dutasteride, which block the enzyme, shrink the gland by 20 to 30% and lower the chances of urinary retention and surgery. Androgens appear to be necessary but not sufficient, though. Testosterone falls with age while BPH rises, so something else must tip the balance.
The review points to three candidates. The first is a growth-factor network built around IGF. IGF is raised in BPH tissue and interacts with TGF-beta, a scar-promoting signal, in the prostate’s supporting tissue. The second is chronic inflammation, which is common in BPH specimens and has been linked to faster progression and a higher risk of urinary retention. The third is metabolism. In a Baltimore cohort, each extra point of body mass index went with about 0.4 milliliters of extra prostate volume, and severely obese men had roughly 3.5 times the odds of an enlarged gland compared with men of normal weight. The authors propose that insulin resistance, a hormonal shift toward estrogen, narrowed pelvic arteries and low-grade inflammation all feed prostate growth and urinary symptoms.
Genes matter too. Twin studies put the heritability of BPH and urinary symptoms at 50 to 70%, although only one genetic variant, in the vitamin D receptor gene, has held up consistently across populations.
The review also lists some intriguing leads. The diabetes drug metformin blunted testosterone-driven prostate growth in rats, and pomegranate extract, ginseng and vanillic acid had effects in animal models. None has been tested in a proper human trial.
One clinical point is easy to miss. Among older men with urinary symptoms, about 60% have an overactive bladder, while only 30 to 40% have a prostate that is actually obstructing urine flow. Prostate size alone is a poor guide to what is causing the symptoms.
The paper has clear limits. It is a narrative overview of 26 references, not a systematic analysis. The take-home is modest but useful. Androgens set the stage for prostate growth, and metabolic health and inflammation may decide how far it goes. No long-term trial has yet shown that improving those factors actually prevents BPH.
Actionable Insights
These points combine what the review says with well-established trial data. The review itself tested nothing.
- Keep weight and waist in check. Each BMI point was linked to about 0.4 mL more prostate volume, which is small on its own. Severe obesity, though, carried about 3.5 times the odds of an enlarged prostate (Cohen’s d about 0.7, a medium effect). Whether losing weight shrinks the prostate has not been tested.
- Stay active. Separate meta-analysis data, not covered in this review, link higher physical activity to up to 25% lower BPH risk.
- Find out what is causing your symptoms. Bladder overactivity is present in about 60% of older men with symptoms and obstruction in only 30 to 40%, so treatment should follow testing, not prostate size alone.
- Match the drug to the goal. Alpha-blockers ease symptoms quickly but do not shrink the gland. 5-alpha reductase inhibitors shrink it by 20 to 30%. In a four-year trial they cut acute urinary retention from about 7% to 3% and surgery from about 10% to 5%, so roughly 1 in 20 to 25 men treated avoids one of these events. Daily tadalafil gives a modest symptom benefit.
- Skip the unproven options. The evidence for metformin, pomegranate and ginseng in BPH is animal-only.
Context and Source
- Open Access Paper: Pathophysiology of Benign Prostatic Hyperplasia and Benign Prostatic Enlargement: A Mini-Review
- Institutions: Department of Urology, Kaiser Franz Josef Hospital, Vienna; Sigmund Freud Private University, Vienna; Department of Urology, Medical University of Innsbruck
- Country: Austria
- Journal: Gerontology (S. Karger AG), 2019
- Impact evaluation: The impact score of this journal is 3.1, evaluated against a typical high-end range of 0 to 60+ for top general science and medicine journals, therefore this is a Medium impact journal.












