Image for human growth hormone More muscle, less fat, restored energy, enhanced sexual performance, improved memory, firmer skin, and regrowth of hair—these are just some of the antiaging claims of human growth hormone therapy. Could a cure for aging really be found in a bottle?

The quest for eternal youth may well be as old as man himself. And to date, there is no magic remedy. But ever since a study published in the New England Journal of Medicine in 1990 reported that supplementing human growth hormone (HGH) to otherwise healthy older men, resulted in increased muscle mass and decreased body fat, many are touting HGH therapy as the new fountain of youth.

But researchers are still in the early stages of understanding the actual effects of supplemental HGH on the aging process. In 2003 the New England Journal of Medicine effectively called into question the 1990 report and expressed strong editorial doubts about HGH effectiveness, concluding that “antiaging therapy with growth hormone has not yet been proved effective according to objective outcome criteria.”

What Is HGH?

Growth hormones are naturally produced by the pituitary gland and are necessary to stimulate growth in children. Doctors have traditionally used man-made HGH to treat children with certain conditions that cause abnormal growth, including growth hormone deficiency, kidney disease , Prader-Willi syndrome , and Turner’s syndrome .

Starting in one’s twenties, the amount of growth hormone begins to decrease and the effects of aging begin. Some scientists believe that by restoring levels of growth hormone in the body, it may be possible to reverse some of the effects of aging.

Promising Areas of HGH Therapy

Because this is a new area of research, there is a lack of published data on HGH and aging. So far, most of the research has focused on the effects of HGH on body composition and strength.

Body Composition and Strength

Research has shown that short-term HGH therapy in older individuals improves body composition, but not muscle strength or cardiovascular endurance.

A study published in the April 15, 1996 issue of Annals of Internal Medicine looked at the effects of HGH therapy in 52 healthy older men. The men received either HGH or a placebo (inactive treatment) three times a week for six months. On average, those who received HGH gained 4.3% more muscle and lost 13.1% of their body fat, while those who received the placebo lost 0.1% of their muscle and gained 0.3% more body fat. Despite these differences, however, there was no significant difference in strength gains between the two groups. The HGH group also reported many more side effects than those receiving the placebo, the most common of which was edema (accumulation of fluid), reported by 65%.

Another study published in the November 13, 2002 issue of the Journal of the American Medical Association compared the effects of HGH or placebo on 131 older women and men. As in the previous study, they found that the participants receiving HGH gained muscle and lost fat, but did not become stronger. But again, their improved body compositions often came at a price of side effects, including diabetes , carpal tunnel syndrome , and edema.

In contrast to these findings, research has clearly established that resistance training safely improves body composition and muscle strength in older individuals. To compare strength training with HGH therapy, a study in the July 2001 issue of the Journal of the American Geriatric Society examined the effects of six months of HGH alone, HGH and strength training, strength training alone, or placebo alone among 31 older adults. The study found that both of the strength training groups became significantly stronger, demonstrating that HGH was not necessary to gain strength, exercise was.

Cognitive Function and Mood

A study published in the Annals of Internal Medicine also looked at the effects of HGH on cognitive function and mood. The researchers found inconsistent results in the cognitive function tests, ranging from improvement to no difference to worsening. And they found no difference in the moods of the two groups. More research is necessary to understand how and if HGH affects cognitive function and mood.

Weighing Your Decision

Authentic HGH supplements are available by prescription only and must be injected into the body. What’s more, a year's worth rings up to over $15,000—a hefty price when compared to the cost of a gym membership.

Dietary supplements marketed as “growth hormone releasers” are much cheaper and are readily accessible, but there is even less evidence to support their many youth-promising claims. In fact, none of the HGH formulations on the market have been proven effective scientifically. And because they are marketed as dietary supplements, the US Food and Drug Administration ( FDA) doesn’t have to regulate their safety. Of course that doesn’t stop thousands of companies from trying to sell these supplements.

So if you’re waiting for youth in a bottle, your wait is not over. In the mean time, talk with your doctor about a healthful diet and beginning an exercise program. There may be no magic about it, but it guarantees results when taken as recommended.