Can human growth hormone slow aging?

Dear Cecil: What is the story with human growth hormone (HGH)? I know that the actual hormone can be injected (at great expense), and some of the Hollywood crowd supposedly use this to stay young. However, a lot of companies are marketing “HGH enhancers,” which are not HGH but supplements that are supposed to stimulate the body to produce HGH in greater quantities. The enhancers are much less expensive than actual HGH and supposedly almost as effective in raising your HGH level. So, does HGH really restore your youth? Do these HGH enhancers work? Or is it all placebo effect? Richard Nash, via e-mail

Cecil replies:

Chances are you’re going to be hearing a lot about HGH in the next few years. Consider the following facts: (1) The most promising test done on HGH so far involved men age 60 and up. (2) The leading edge of the baby-boom generation is now 58. If you’re, say, Bill Clinton, born in 1946, you’re looking in the mirror and thinking: You know, for an old fart, I don’t look bad. How long can I hold off the inevitable? (3) Most of the crap you see touting HGH and so-called HGH enhancers is, in fact, crap. (4) However, some of it’s not.

Here’s the story so far. HGH is a chemical produced by the body that’s essential to normal growth in children, and scientists have now come to realize it’s important in adults, too. In many but not all elderly people, HGH levels drop well below those of adults in their prime, and some researchers think this leads to loss of lean body mass, increased body fat, and other hallmarks of aging. Before the mid-80s the sole source of HGH was the pituitary glands of cadavers, but gene-splicing technology has made it possible to produce synthetic HGH in quantity, though still at a stiff (sorry) price. To date the stuff has mostly been given to people with gland problems, e.g., kids who would otherwise be abnormally small. In 1990, however, the New England Journal of Medicine published a study by D. Rudman et al suggesting that giving synthetic HGH to healthy males over 60 with reduced levels of natural HGH significantly slowed aging. The Rudman group injected 12 men ages 61 to 81 with HGH three times a week. After six months they found that the men averaged 9 percent more lean body mass, 14 percent less body fat, 7 percent greater skin thickness, and a 2 percent increase in lumbar vertebra density. Meanwhile a control group showed no change.

In an accompanying editorial, the NEJM said in essence: This is pretty cool (the sober world of medical research being what it is, the actual phrase was “an important beginning”). But we don’t know enough about possible long-term effects of supplemental HGH, and much of what we do know isn’t good — drawbacks include increased risk of diabetes, arthritis, and congestive heart failure. So don’t go running out to Rexall just yet.

Internet hucksters paid no attention. Some spammed the world about dietary supplements that supposedly increase the body’s production of HGH; meanwhile, several Web sites hawked oral or inhaled versions of HGH. Many cited the Rudman study as support for their claims. The NEJM got fed up and published more articles saying: we’ve never endorsed the use of HGH to combat aging, we’ve seen no proof that so-called enhancers have therapeutic value, oral and inhaled HGH probably won’t work for technical reasons, and dietary supplements aren’t regulated by the FDA. (All of the articles, including the Rudman study, are available on the NEJM Web site at no charge.)

Hype notwithstanding, the role of HGH in aging remains a subject of intense scientific interest. A quick search of PubMed, an online medical journal index provided by the National Library of Medicine, shows roughly 150 reports on HGH and aging since the beginning of 2000. Data points pro and con:

Multiple follow-up studies have confirmed the Rudman findings, although the ones I’ve seen were short-term and involved relatively few subjects. On the other hand, the impact of HGH on mental function — which many think is the key to long life — remains unclear.
In one study, 18 men aged 65 to 82 underwent progressive strength training followed by more training plus HGH or placebo. The initial training significantly increased muscle strength, but HGH produced no additional benefit.
Elevated levels of HGH derivative in the blood may increase the risk of cancer; reduced levels are associated with heart attack and atherosclerosis.

You’re thinking: I’m getting mixed signals here. Exactly — we still don’t know enough about HGH to proclaim it an elixir of youth. Luckily, other promising methods for cheating the reaper are available now and don’t require expensive chemicals — exercise, for instance, or sharply reducing calorie intake. But the average American is likely to say, I think I’ll wait for HGH.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.