The role of estradiol in men is limited but it plays a significant role in maintaining a man's reproductive capability. Estradiol is a sex hormone that regulates a woman's menstrual cycle. In men, the hormone is produced in much smaller amounts. The estradiol in men prolongs the lives of sperm cells, increasing the chances that during intercourse, viable sperm cells reach the ovum. If levels of estradiol in men are too high or low, it can have a negative effect.
Estradiol is a sex hormone produced by the ovaries in women and testes in men. In both cases, estradiol is converted from testosterone. Its role is best understood in regulating women's menstrual cycle. During a woman's menstrual cycle, a rising level of estradiol prompts the release of one ovum, or egg, from the ovaries. Levels are lowest during menstruation, but remain at their peak if a pregnancy occurs.
A typical adult male generally has anywhere between a fifth and half as much estradiol in his bloodstream than a comparable woman. This deficiency is natural as estradiol is an estrogen; high levels of estradiol lower sperm counts in men. Yet in low levels, estradiol has a positive effect on a man's ability to reproduce.
All cells eventually go through apoptosis, or programmed cell death. This process is essential to avoid the development of cancers and other ailments. The presence of estradiol in men delays apoptosis in sperm cells. As estradiol is only produced in the testes in men, sperm cells receive the maximum benefit from estradiol and have a higher chance of surviving the journey between the testes and ovum.
Though the proper level of estradiol in men can give a reproductive advantage, low or high levels can do more than affect reproduction. Research published in 2009 suggests that men with low or high levels of estradiol will more likely suffer from heart failure. Consequently, readjusting estradiol levels in men with heart failure increases heart functionality. The research notes, though, that its results are only preliminary and that it may take years for consistently effective estradiol treatments to become available.
Another, more serious complication from high estradiol in men is an increased risk of prostate cancer. A rise in estradiol and decrease in testosterone are both markers that a man's hormones have become imbalanced, an event that can occur after the age of 40. Though other factors such as genetics influence a man's chances of developing prostate cancer, annual blood tests can reveal a hormone imbalance before cancer develops. Early detection is key in reducing a man's chances of dying from prostate cancer.