Illustration by Jonathan Carlson
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Dr. Debunker
The Truth About the Fountain of Youth
By Andrew Weil, M.D., May & June 2007
How to live a healthy, vigorous—and long—life. No gimmicks
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You’ve surely heard the claims—on television, in magazines, on the Internet: take this antiaging product and you’ll live forever (or, if not forever, significantly longer than everyone else). And people line up with credit cards in hand to pay for these products and services.
As a physician who has long embraced the concept of integrative medicine—combining scientifically validated alternative therapies with conventional medical treatments—I have followed closely the claims of the antiaging and life-extension movements. And with all due respect to my physician colleagues who practice antiaging medicine, the truth is that most of the antiaging treatments on the market today are modern-day snake oil.
Human Growth Hormone
Take, for instance, human growth hormone (HGH), available by prescription as an expensive ($15,000 a year) therapy taken by daily injection. HGH, produced naturally by the pituitary gland, is necessary for growth and development in early life, especially for maintenance of healthy bone and muscle mass. Production declines normally with age. All the enthusiasm for supplemental HGH (a synthetic form) derives from a single published report in The New England Journal of Medicine in 1990. In it, Daniel Rudman, M.D., and his colleagues described the results of a study of 21 healthy men—ages 61 to 81—12 of whom received thrice-weekly injections of HGH. After six months, those 12 had a significant increase in lean body mass and bone density and a decrease in body fat compared with the untreated controls.
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It is hard to believe that one article reporting a short-term study in such a small population could have launched an entire antiaging movement, but that’s exactly what happened. Proponents of antiaging medicine seized on this study, which they interpreted as evidence that HGH could turn back the clock, and sales of synthetic HGH skyrocketed.
The problem is that subsequent studies of HGH have found no correlation with longevity but instead a potential for such side effects as high blood pressure and elevated cholesterol and blood sugar levels. In the January 16, 2007, issue of Annals of Internal Medicine, Hau Liu, M.D., a researcher at the Stanford University School of Medicine, reviewed 18 major published studies on HGH therapy and aging and found no data to support the antiaging and life-extending claims made for HGH, but he did find “there was substantial potential for adverse side effects.” Moreover, since the FDA allows adult use of HGH for just three conditions—the wasting syndrome of AIDS, short-bowel syndrome, and growth hormone deficiency documented by specific tests—administration of HGH to healthy adults is not only unscientific but illegal.
Caloric Restriction
Another approach to extending life that has gotten a tremendous amount of media attention is caloric restriction. Decrease the number of calories that an animal eats by a third and it will live longer and stay in better health than its better-fed counterparts. Every animal species tested responds this way, including primates, and there is every reason to think humans would, too.
The fixation on antiaging and life extension can distract from the important goal of healthy aging.
In a nutshell, the body seems to interpret caloric restriction as a signal that the environment is turning hostile. This signal activates master regulator genes that slow metabolism so the organism can hunker down and wait out the bad time. By tinkering with these genes in simple organisms, molecular biologists have extended life spans remarkably.
Biologists are also finding ways to mimic these results without cutting back on food. The recent excitement about resveratrol, an antioxidant found naturally in the skins of grapes, comes from experiments showing it reproduces the life-extending effect of caloric restriction in certain lower species such as worms and fish.
This line of research is compelling, but I have a number of concerns about its applicability to humans.
- Even if caloric restriction proves to be an effective means of extending life and health, few of us will go for it. A 50-year-old female, for example, might be eating as few as 1,000 calories a day.
- People who practice caloric restriction tend to be extremely lean with little body fat. Undoubtedly, this is better for their hearts, but it could make them more susceptible to other illnesses, including Parkinson’s and ALS.
- There is not enough resveratrol in red wine or grapes to give you the effect seen in worms and fish. You could take large doses as supplements, but we have no data at all on the safety or efficacy of those doses in humans.
- Manipulation of the master regulatory genes that influence life span in lower organisms might have unforeseen and disastrous consequences—such as increased risk of cancer—in more complex organisms like us.
It is theoretically possible that human life span can be extended, but I doubt that it will happen anytime soon.
In fact, I consider the fixation on antiaging and life extension to be a distraction from the important goal of healthy aging. That is, we should concentrate on making positive lifestyle choices now—eating better, exercising more, getting enough sleep, even improving our mental state—so that we can enjoy not just a longer life but a healthier one. Of course, eating right and exercising more aren’t as easy as getting HGH injections, but then, the best things in life rarely are.
Andrew Weil’s latest book is Healthy Aging: A Lifelong Guide to Your Well-Being (Anchor, 2007).
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