From the fruitless quest for the legendary Fountain of Youth to the current popularity of plastic surgery and Retin-A face cream, the search for ways to erase the sags and wrinkles of aging has never stopped. Now it appears that a partial antidote to the ravages of time may already lie within the human body. Last week, researchers at the Medical College of Wisconsin and the Veterans Affairs Medical Center in Milwaukee reported in the New England Journal of Medicine that injections of a naturally occurring substance called human growth hormone can firm up skin, build muscles and trim fat in elderly men, . making their bodies look up to 20 years younger. While there is no evidence that the treatment can enable people to live longer, it may one day help many of the aged appear and feel more robust.
HGH apparently reverses some signs of aging by changing the body's composition. Some 80% of a young adult's body consists of so-called lean body mass -- muscles, organs and bone -- and the remaining 20% is made up of fatty, or adipose, tissue. But after age 30 the muscles begin to atrophy, the skin thins out and lean body mass is replaced by adipose tissue at an average rate of 5% a decade. By age 70 the balance between fat and lean may be fifty-fifty.
For years it was thought that these changes were inexorable and irreversible, but it is now clear that they are influenced by changing levels of HGH. Produced by the pituitary gland at the base of the brain, the hormone stimulates the growth of bones and organs in children and helps maintain healthy tissues in older people.
HGH levels naturally drop over time; by age 60 about 30% of men produce little or none of the substance. Although researchers had long suspected that lower levels of growth hormone might play a role in the aging process, it was not until the late 1980s, when a synthetic form of HGH began to be mass- produced in the laboratory, that enough was available to test the hypothesis. Until then, nearly the entire supply of HGH, which was extracted in minuscule amounts from cadavers, was used to treat children suffering from dwarfism.
The Wisconsin study, led by Dr. Daniel Rudman, was the first to test the effects of HGH in healthy elderly patients. The experiment involved 21 men between the ages of 61 and 81 who had negligible levels of HGH. Twelve of the men gave themselves injections of synthetic hormone three times a week for six months; the others received no treatment. All the subjects followed a diet of about 15% protein, 50% carbohydrates and 35% fat but were told not to alter their life-styles, including the amount they smoked and drank.
After six months, the men taking HGH felt healthier and more energetic, almost like the old characters who were rejuvenated in the movie Cocoon. The group's growth hormone levels rose to those of men under 40. Fatty tissue decreased nearly 15%, lean body mass increased 9%, skin grew 7% thicker and some vertebrae became slightly denser. In several respects, the researchers say, HGH therapy reversed the consequences of a decade or two of aging. Men in the control group showed no significant changes in their physiques.