Sex hormone levels drop as you age -- and as they do, so does your sexual desire, energy and mood.
But could replacing lost hormones reverse the aging process?
Unfortunately not, according to new research. Sex might be great, but sex hormones are no fountain of youth.
Levels of testosterone, the male sex hormone, decrease in men as they age. Another hormone, dehydroepiandrosterone, known as DHEA, also decreases with age. DHEA levels start dropping in both men and women as early as age 30.
Women don't have much testosterone in their bodies, but both sexes have DHEA. And, according to some studies, men and women with higher levels of DHEA live longer lives.
So, if DHEA levels are kept artificially high with hormone supplements, could men and women regain some of their youth?
New research published in today's New England Journal of Medicine suggests that sex hormone replacements do not turn back the clock.
A group of researchers from the Mayo Clinic in Rochester, Minn., are the first to have looked at the long-term effects of sex hormone replacements in older men and women.
The researchers studied nearly 90 men and 60 women over age 60 whose hormone levels had decreased with age. They wanted to know if certain supplements could increase hormone levels, and if these levels did increase, what benefit or harm that would bring. The doctors passed out DHEA pills and testosterone patches to the men, and DHEA pills to the women. Some of the patches and pills were fakes, but neither the doctors nor the study volunteers knew which ones were which.
At the end of two years, the hormone-taking men and women did have increased levels of sex hormones in their blood compared with those who had received fake pills or fake patches. But these hormone increases didn't make the volunteers any younger, as the supplement industry often promises.
"We found no difference in quality of life, including sex drive," said Dr. Sree Nair, lead author and professor of medicine at the Mayo Clinic.
Higher hormone levels also made no difference in specific hallmarks of aging that were measured during the study: physical endurance, bone strength, body fat content or the body's ability to process sugar.
The study's authors concluded there is "no evidence that either DHEA or low-dose testosterone is an effective anti-aging hormone supplement, and they argue strongly against the use of these agents for this purpose."
Hormones didn't help set back aging, but they also did not produce any side effects. If the hormones are harmless, is there anything wrong with popping a few hormone pills?
Most experts said supplements may not always be safe, even if some studies suggest they aren't dangerous. And since the government does not regulate supplements, you can't always know what you're getting from a given pill.
"There may be ingredients that are not even listed on the label. So buyer beware," said Dr. Linn Goldberg, professor of medicine at Oregon Health and Science University.
Past studies on testosterone have shown undesirable effects, even though researchers did not see those in the recent Mayo Clinic study. "[Testosterone] is not a cure-all for aging and has potential dangers if you have prostate cancer," said Dr. Edward Schneider, past deputy director of the National Institute on Aging.
And even though this study was a long one -- lasting two years -- the even longer-term effects of these hormones are still a mystery.
"You just don't know what's going to happen in five or 10 years," said Goldberg.
Sex hormones may not be the answer to an anti-aging regimen, according to this study.
Experts said stick to strategies that have proved effective in ameliorating the effects of aging. "Save your money, exercise, eat right, watch your waistline and get a good night's sleep," said Schneider. "That's the secret to being ageless."