What Causes an Enlarged Prostate?

Experts do not know for certain what causes BPH, but they have established a list of risk factors. As is usually the case, some of the risk factors are things you can control while others you can not.

Here are 15 risk factors for BPH that fall into both categories:

1. Age

The half-century mark seems to be the tipping point when it comes to greater risk of developing BPH.  While slightly more than 20 percent of American men ages 40 to 49 have symptoms of BPH, this figure rises to 35 percent among men 50 to 59, 58 percent in the 60 to 69 age group, and 84 percent in men age 70 and older.  Factors that may contribute to the age-related risk of developing BPH include changes in hormone levels and damage to the blood vessels that supply the prostate and surrounding structures. When the prostate cells are deprived of enough blood, some experts speculate that this triggers the unwanted growth.

2. Family history

Men who have a close male relative (father, grandfather, brother, son) who have BPH have an increased risk of getting the disease, especially if their relatives had symptoms severe enough to require treatment before the age of 60.

3. Excessive DHT

DHT is the acronym for dihydrotestosterone, a substance that is the result of a conversion of testosterone by an enzyme called 5-alpha reductase. BPH is an “androgen-dependent disease,” which means it is influenced by the male hormone (androgen) testosterone. The prostate will not grow unless it is “directed” to do so by testosterone, which is made mainly by the testes. Boys who have their testicles removed before they reach puberty will never develop BPH, and removing them after puberty but before BPH develops dramatically reduces the chance of suffering from the disease.

But testosterone alone is not the bad guy: it must be converted by 5-alpha-reductase into DHT, and the DHT is what promotes the prostate cells to grow. Experts believe DHT levels rise in many men as they age, even if testosterone levels decline, and that the buildup of DHT may be a factor in BPH.

4. Elevated estradiol

It’s natural for men to have some of the female hormone estrogen (in the form of estradiol). Estradiol is produced as a byproduct of conversion of testosterone, among other means. The proper balance of estrogen-to-testosterone in men is important for a healthy sex drive, to enhance brain function, protect the heart, and strengthen the bones. When estradiol levels are too high, however, and the ratio is out of balance, men can experience fatigue, increased body fat, loss of libido and an enlarged prostate. An imbalance between estrogen and testosterone increases DHT activity, and thus encourages prostate cells to grow.

5. Overweight/Obesity

Being overweight, especially around the midsection, raises the risk of excessive prostate growth. (Zucchetto 2005; Enlarged Prostate, AUA) A review study published in July 2009 also noted a strong relationship between obesity and the development of BPH and lower urinary tract infections.  The link between obesity and BPH may be related to the reduced testosterone levels seen in the obese. Also, a drop in testosterone means there’s an accompanying rise in estrogen levels, which can increase the activity of DHT and thus prostate growth. Obesity also affects insulin levels in the blood, which is another risk factor for BPH (see below).

6. Diabetes

Having diabetes is one of the risk factors for BPH, perhaps a significant one. (Sarma 2009) Research indicates it may be due to elevated insulin levels, which not only “corral” the blood sugar and usher it into the cells, but also stimulate growth. (Nandeesha 2006) The diabetes-BPH link may also be related to the damage that diabetes does to blood vessels. If the vessels that service the prostate are damaged, an enlarged prostate may be the result. (Berger 2005)

7. High “Bad” Cholesterol

In 2008, researchers at the UCSD School of Medicine reported that among men with diabetes, those who had higher levels of the notorious “bad” cholesterol, low-density lipoprotein (LDL), were more likely to develop BPH than men who had normal LDL levels. (Parsons 2008) When the researchers divided the men into three groups (high, medium, low), those with “high” LDL levels were four times more likely to have BPH than those in the “low” group. (The levels of total cholesterol and triglycerides, which are commonly called blood fats, were not linked to BPH in this study.)

8. High blood pressure

Although no one is exactly sure how high blood pressure may trigger or worsen BPH, researchers have found a link between hypertension and BPH. (Nicolas 2003)

9. Metabolic syndrome

Also referred to as “Syndrome X,” metabolic syndrome is a cluster of disorders that increase the risk of developing cardiovascular disease. These disorders include obesity, elevated blood pressure, glucose intolerance or insulin resistance (the inability of normal amounts of insulin to transport blood sugar into cells on command), a pro-inflammatory state (elevated C-reactive protein in the blood), and a prothrombotic state (high fibrinogen or plasminogen activator inhibitor-1 in the blood). Researchers discovered that these factors also are risk factors for BPH. A group of Swedish scientists have suggested that BPH and metabolic syndrome may be linked by problems with insulin and blood sugar regulation, which results in elevated levels of insulin. (Hammersten 1998)

10. Atherosclerosis

If you have atherosclerosis–the hardening and thickening of artery walls caused by the accumulation of plaque—you may be at increased risk for BPH, according to at least one study. (Berger 2006)

11. Ethnicity

Results of a large-scale study published in 2008 found that black and Hispanic men are more likely to develop BPH than white and Asian men. However, other studies have not found much difference between ethnic groups. (Hoke 2008)

12. Sedentary lifestyle

A lack of exercise may increase your chances of developing BPH, possibly because exercise helps fight obesity, type 2 diabetes, insulin resistance, and other risk factors associated with BPH. (Moyad 2003)

13. Poor diet

According to a 2008 study published in the American Journal of Epidemiology, consuming greater amounts of vegetables and lesser amounts of fat and red meat may reduce the risk of developing BPH. (Kristal 2008) For example, the study showed that eating a high-fat diet raised the odds of developing BPH by 31 percent, while eating red meat daily increased the chances by 38 percent. However, if you consume at least four servings of vegetables daily, you can reduce your risk by 32 percent.

The exact role that fat plays in causing the prostate to grow is not understood, although researchers have some ideas. Fat has the ability to increase the levels of testosterone, estrogen, and other hormones, which have been linked with BPH. Fat also is associated with chronic inflammation, which can cause prostate enlargement and play a role in prostate cancer.

14. Alcohol consumption

A study in the American Journal of Epidemiology found that two drinks per day have a protective effect against BPH. (Kristal 2008)  One possible explanation is that alcohol lowers the levels of certain hormones and encourages muscles in the prostate to “relax.”

15. Weak immune system

Exercise, poor diet, stress and poor lifestyle can all compromise and weaken the immune system leading to disease and inflammation and an increased risk of prostate disease. A strong immune system is promoted by leading a prostate friendly lifestyle based on the 6 Pillars of Prostate Health.


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Berger AP et al. Atherosclerosis as a risk factor for benign prostatic hyperplasia. BJU International 2006 Nov; 98(5): 1038-42

Hammarsten J et al. Components of the metabolic syndrome risk factors for the development of benign prostatic hyperplasia. Prostate Cancer and Prostatic Diseases 1998 Mar; 1(3): 157-62

Hoke GP, McWilliams GW. Epidemiology of benign prostatic hyperplasia and comorbidities in racial and ethnic minority populations. American Journal of Medicine 2008 Aug; 121(8 Suppl 2): S3-10

Kristal AR et al. Dietary patterns, supplement use, and the risk of symptomatic benign prostatic hyperplasia: results from the prostate cancer prevention trial. American Journal of Epidemiology 2008 Apr 15; 167(8): 925-34

Moyad MA. Lifestyle changes to prevent BPH: heart healthy = prostate healthy. Urologic Nursing 2003 Dec; 23(6): 439-41

Nandeesha H et al. Hyperinsulinemia and dyslipidemia in non-diabetic benign prostatic hyperplasia. Clinica Chimica Acta 2006 Aug; 370(1-2): 89-93

Nicolas Torralba JA et al. Relation between hypertension and clinical cases of benign prostatic hyperplasia. Arch Esp Urol 2003 May; 56(4): 355-58

Parsons JK et al. Lipids, lipoproteins and the risk of benign prostatic hyperplasia in community-dwelling men. BJU International 2008 Feb; 101(3): 313-18

Sarma AV, Kellogg Parsons J. Diabetes and benign prostatic hyperplasia: emerging clinical connections. Current Urology Reports 2009 Jul; 10(4): 267-75

Zucchetto A et al. History of weight and obesity through life and risk of benign prostatic hyperplasia. International Journal of Obesity (London) 2005 Jul; 29(7): 798-803