The prostate is composed of glands and muscle. With increasing age these tissues grow, resulting in enlargement of the prostate (BPH). BPH is rare before age 40, but is present in about 80% of men by age 80. About half of these men will have symptoms from the enlarged prostate. We do not know what causes BPH but it appears to be related to subtle changes in hormone production, which occur with aging and, possibly, as a result of environmental factors such as diet.
BPH is not a cancer. BPH causes problems because as the prostate enlarges, it compresses the urethra and blocks the passage of urine from the bladder. This can prevent the bladder from emptying, sometimes causing damage to the bladder and kidneys, or the inability to pass urine. These serious effects are relatively uncommon; the more usual result of BPH is bothersome symptoms while urinating.