If you thought the hormone estrogen was only useful for menopause, osteoporosis and heart disease, think again. Both estrogen and the male sex hormone testosterone have been linked to a bounty of benefits for men and women alike.
In fact, these hormones are so woven into our physical well-being that the benefits span vision, muscle, sex, memory and complexion - not to mention protection against a host of killer diseases.
Although estrogen and testosterone are not generally prescribed for the following conditions, if your doctor decides they may be helpful for other symptoms, you may notice some surprises.
Let's start with muscles for men and libido for women. Walk through this list, and you'll learn a lot about how the waxing and waning of our hormones affects well-being.
Testosterone Therapy Boosts Male Libido
Hormone replacement therapy has become a fact of life for many midlife women. Soon, perhaps, it could be as common for midlife men.
In the same way as supplemental estrogen is seen as essential for the maintenance of healthy bones and straight backs in women, testosterone has also been linked with bone-thinning and osteoporosis in men. Some two million men in the United States suffer from osteoporosis and another three million are at risk.
In addition, a low level of testosterone has been linked with poor sexual functioning and low libido in men. Prescription skin patches such as Androderm and Testoderm may be helpful but require close monitoring.
You May Find Sex Is Better With Hormones
For too long, doctors have thought that estrogen replacement was the equivalent of Viagra when it came to the waning sex drives of midlife women. Increasingly though, that spotlight has been hijacked by testosterone. While estrogen replacement can improve vaginal lubrication during intercourse, testosterone is the hormone that is most closely associated with desire.
A woman's body produces both the male and female hormones estrogen and testosterone. As we age, production of these two hormones takes a nosedive, and approximately 60 percent of women experience a decline in sexual functioning, according to Yale researcher Dr. Philip Sarrel.
Sarrel is the author of a study that found that women who were given supplemental testosterone reported a significant increase in their sex drive compared to those who received estrogen alone or estrogen in combination with progesterone.
Estrogen Helps Women Maintain Balance
We know that estrogen helps prevent bone-thinning, a condition that makes both men and women vulnerable to hip fractures, one of the leading causes of death among older women.
But new research indicates that estrogen may prevent fractures in a second way. It is believed that the drop of estrogen that accompanies menopause may affect the central nervous system and impair balance.
But supplementary estrogen may correct this imbalance by increasing blood flow to the brain, some doctors believe.
In a Swedish study of 19 women aged 47 to 59 all the participants were found to have significantly improved balance after taking estrogen for 12 weeks. Balance was measured by a series of tests that assessed the subjects' gait and equilibrium.
Estrogen Helps Preserve Skin's Firmness
We know that a wrinkle-free complexion is a young complexion - or an older one that has been shielded from the sun. New evidence suggests that smooth, mature skin may also owe its youthful appearance to supplemental estrogen.
Estrogen may improve the condition of the skin by preserving collagen content and thickness, according to researchers of a study that looked at the link between the hormone and wrinkles.
Among women who took estrogen, the odds of having wrinkled skin were found to be 30 percent lower than those who did not take the hormone, reports Dr. Gail Greendale, a professor of medicine at the University of California at Los Angeles and co-author of the study.
After adjusting for smoking and sun exposure, estrogen still appeared to have a protective effect against wrinkling, the authors noted.
A Message for Women at Risk for Diabetes
Can supplemental estrogen prevent diabetes? Possibly.
Nobody knows exactly why, but in a study of 418 women, researchers from the University of Wisconsin in Milwaukee found that older women who did not take supplemental estrogen were five times more likely to develop Type 2 diabetes as those who did.
Lead researcher Mary Ruth Lambert advised women at risk for diabetes to consider estrogen therapy.
A second, larger study of 14,600 women found that those who did not use estrogen had higher blood-glucose levels - a possible forerunner of diabetes - than those who did.
Estrogen and Eye Health
As the body ages, the lenses of the eye begin to cloud like eyeglasses fogged with steam. In many cases, this clouding is due to cataracts, a common condition resulting from the gradual deterioration of the clear proteins in the eye.
Until recently, it was believed that the only means of preventing cataracts was by shielding the eyes from the sun.
But research from Spain shows that women who take estrogen have a lower risk of developing cataracts than those who do not.
Ophthalmologists from Madrid compared the transparency of the lenses of 19 women who took estrogen for more than four years with that of 43 age-matched participants who did not take the hormone, including 23 men.
The lenses of the estrogen group were found to have a higher transparency than those of the men and women not taking estrogen.
Estrogen Cuts Risk of Colorectal Cancer
This year, 56,600 Americans will die of colorectal cancer (cancer of the colon or rectum). Colorectal cancer is the third most commonly diagnosed cancer for both men and women, according to the American Cancer Society.
It's known that a high-fiber diet and regular colonoscopies can prevent the condition. So, it seems, can supplemental estrogen.
In a study of 7,700 postmenopausal women, lead researcher Annlia Paganini-Hill found that the risk of developing colorectal cancer for participants who were recent users of estrogen was one-third lower than those who had never used it.
Paganini-Hill also found that participants who had used estrogen at some point had a 19 percent lower risk of colorectal cancer than women who had never used it.
Colorectal cancer typically takes 30 to 40 years to develop from normal tissue to tumor. Some doctors speculate that if the participants had taken estrogen earlier, their risk of developing the disease might have been lower. However, the mechanism in which estrogen protects against colorectal cancer is not understood.
Testosterone Therapy Builds Lean Muscle
Build lean muscle without changing your diet or exercising. Sounds like the latest dubious fitness gizmo? Suspend your cynicism before you dismiss this claim.
A recent study has found that older men who use testosterone replacement therapy tended to lose fat mass in their arms and legs and gain lean muscle in the body trunk, when compared with those taking a placebo.
In the study of 96 men randomly assigned a testosterone patch or a dummy patch, researchers found that over a three-year period, the men in the treatment group experienced a 6.6-pound loss of fat and gained 4.2 pounds in lean body mass.
The men in the placebo group did not experience significant weight changes, according to lead researcher Dr. Peter Snyder of the University of Pennsylvania in Philadelphia.
However the treatment group did not lose visceral fat, the abdominal fat surrounding organs, which have been linked to a greater risk of heart disease.
Testosterone Found to Improve Memory in Men
Forget the endless mental acrobatics. Testosterone could be the answer, according to the findings of scientists at Oregon Health Sciences University in Portland.
The researchers found that older men treated with testosterone improved their ability to retain information and update their memory as new data became available.
How long will losing one's memory remain an inevitable part of growing older? Among men in their 70s, testosterone was found to bolster memory to a level equivalent to the average for those in their 30s or 40s.
It is not known exactly how testosterone improves memory, according to researcher Jeri Janowski, but it is thought to affect the frontal lobe of the brain, where we organize time and information.