As men age, the prostate gland enlarges. This is also known as benign prostatic hyperplasia (BPH). BPH is a noncancerous growth of the cells within the prostate gland. By age 60, more than half of men have BPH. By age 85, about 90 percent of men have BPH, but only about 30 percent will have symptoms. An enlarged prostate can put pressure on the urethra which makes it difficult to urinate. It is unclear what causes benign prostatic hyperplasia. However, what we do know is that age and testosterone play an important role. Other risk factors include poor diet, physical inactivity, abdominal obesity, smoking, and excessive alcohol use.