THE BLOG
12/29/2010 11:12 am ET | Updated May 25, 2011

Human Growth Hormone: The Secret Ingredient to a Longer Life or Just Nicer Skin?

In 1990, a scientist at the Medical College of Wisconsin named Daniel Rudman published a study that gave birth to the modern anti-aging movement. Rudman's paper, which was published in the New England Journal of Medicine showed that 12 men who were given injections of human growth hormone (HGH) lost 14 percent of their body fat and increased their lean body mass -- including muscle -- by 9 percent. HGH, which is mostly used to help short children grow, became the go-to drug for perfectly healthy, aging people who were in search of the fountain of youth.

Now, one of Rudman's closest friends is throwing cold water on the theory that HGH should be embraced as an anti-aging elixir. St. Louis University professor, John E. Morley, co-published a study in a recent edition of the Proceedings of the National Academy of Sciences showing that inhibiting the body's production of growth hormone -- rather than increasing it -- extends life. "Large numbers of people are taking growth hormone to rejuvenate themselves," says Morley, director of the divisions of geriatric medicine and endocrinology at Saint Louis University School of Medicine. "Our take-home message is that no one should take growth hormones."

Here's why: When Morley and his team gave an HGH-blocking drug to mice that were prone to develop Alzheimer's disease, the mice showed improved cognition skills -- and they lived longer than the mice that didn't get the drug. Furthermore, mice with lower levels of growth hormone were less likely to develop tumors, and more likely to have long telomeres, which are protective caps on DNA that have been linked to increased lifespans.

Will this study dissuade the growing legions of HGH fans? Not likely, Morley concedes. Rudman's research is still quoted on more than 50,000 anti-aging websites, despite the fact that the New England Journal has since posted an article warning patients that there isn't much scientific evidence supporting the theory that it's smart and safe for healthy people to take the hormone. "Once it's out there, people want to believe it forever," Morley says.

Morley points out that even Rudman had doubts about growth hormone. In 1993, Rudman co-published an 18-month study of HGH in 83 healthy men. Several of the men suffered adverse reactions, such as carpal tunnel syndrome and high blood sugar, and 29 participants ended up dropping out of the study. The report, however, attracted much less fanfare than the original Rudman study, because it was published in the relatively unheralded British journal Clinical Endocrinology. Rudman died in 1994.

The next step for Morley's team is to study whether inhibiting growth hormone lengthens the lives of other animals. If that works, Morley says, he may try it in people. His goal, however, is not to use the technique to halt aging, but rather to treat cancer.

As for growth hormone, Morley believes it doesn't do much except improve people's skin tone. "But that's just because it causes water retention," he says. So what does work when it comes to fending off the aging process? "Exercise is good," Morley says.