For thousands of years, magicians, alchemists, even a few fringe medical practitioners have fueled an unbounded optimism that we can blunt the ravages of time, stay younger for longer, maybe even defeat death itself. Their pitches have usually hinged on some drug, food or device - everything from electricity to yogurt to surgically installing the gonads of animals into our own bodies - that will slow or reverse the aging process. Every decade or so, "anti-aging" promoters grasp onto news coming out of research labs and trumpet those developments as the answer we have all been awaiting.

Lately, the buzzwords are "nano," which refers to the science of the ultra small (a nanometer is one millionth of a millimeter), and stem cells. One "nano" face cream, for example, promises to stave off wrinkles with "nano-encapsulated technology" into which the makers have "packed microscopic bundles of Prodew, a nourishing skin humectant." A dietary supplement advertised as "The World's FIRST Stem Cell Enhancer," promises to "Rebuild, Renew, Rejuvenate" - giving you more stem cells and keeping your organs healthy - if you take the blue-green algae capsules. The claims are based on wispy science and hype.

But while the cycle remains the same, something new is happening in the world of anti-aging. Mainstream doctors who once wanted nothing to do with the naturopaths, osteopaths and others who first populated modern anti-aging, and whom they often considered glorified carnival barkers, are buying in, signing up for "certification" as anti-aging practitioners and offering patients the promise of youth and rejuvenation through such treatments as human growth hormone, testosterone, special diet and exercise regimens, antioxidants and hundreds of other supplements.

"It is mushrooming," says Dr. Elliot Snyder, an emergency room physician based in Northern California who follows the movement closely by frequently attending anti-aging meetings and talking to friends in the field. He also uses some of its techniques himself. Besides exercising five days a week and following a strict low-fat diet that includes lots of fruits, vegetables and wild salmon but no white flour or red meat, he takes supplements ranging from thiamin and biotin to DHEA, DMAE, colostrum, arginine, carnitine and omega-3 fatty acids - about 50 pills per day. He is 64 but looks a decade younger.

Back in 1994, the annual Las Vegas meeting of the fledgling XXX was held in a small hotel off the Las Vegas strip. Everyone could fit into a temporary tent-like structure on the pool patio. Last December, at the 15th XXXX confab, roughly 2,000 attendees, including business owners, anti-aging promoters and hundreds of doctors - among them obstetricians, ER docs, psychiatrists and internists - filled a cavernous meeting space inside the Venetian Hotel and Resort.

Today, claims Dr. XX, XXX's co-founder, there are about 20,000 XXX-certified doctors around the world. XXXX's tax returns confirm the boom. The income from fees charged to those seeking board certification from XXXX more than doubled from $544,845 in 2005 to $1.2 million in 2006.

A rival organization, Age Management Medicine Group, is growing rapidly, too, says co-founder Rick Merner. He claims the group had more than 400 doctors at its last meeting, sponsored by the nation's single largest "age-management" clinic, Cenegenics. The Cenegenics Foundation also certifies practitioners in age-management medicine (it shuns the term "anti-aging") and claims to have experienced a 100 percent increase in the number of its physician "affiliates" to more than 800.

Mainstream business has recognized the potential. GE Healthcare, for example, sent a team to the recent XXXX meeting to market body scanners that cost about $100,000 each and are often used by anti-aging doctors to look at fat deposits inside the body and convince patients of the need to do something about them. (Msnbc.com is a joint venture of Microsoft and NBC Universal, which is a GE company.)

'A life-changing experience'
Patients all over the country are buying in. Rebecca Gooden, a 57-year-old Charleston, S.C., real estate agent, first saw an anti-aging doctor in December when she sought help for joint pain, insomnia and lack of energy. "I had felt something was going on but standard testing did not show any of it," she says. "I had been having symptoms but doctors kept telling me there was nothing wrong and I knew there was."
Frustrated, when she saw an article about Cenegenics in a magazine, she called for an appointment in hopes of solving her problems. Now, she spends about $1,000 a month on hormones and supplements to treat various hormonal deficiencies and has become an anti-aging convert. "I feel like a new person ... it has been a life-changing experience for me."

All this despite the fact that as far as the American Medical Association or the American Board of Medical Specialties is concerned, there is no such thing as an anti-aging specialty.

Therein lies the often bitter tension between the medical establishment and those physicians and organizations who say they can help us slow or even stop the aging process and the debilitation that comes with it. Goldman and his XXX co-founder, Dr. XXX, have been accused by respected academics of being snake-oil salesmen. Cenegenics and A4M have both been labeled glorified hormone-pushers.

Anti-aging advocates, on the other hand, argue that they are a persecuted minority of enlightened medical professionals who have the patients' best interests at heart and that the AMA, the mainstream media and the government, especially the Food and Drug Administration, have conspired to keep the truth from the public.

"Certain vested interests would not like to have anti-aging," XX argues.

To the ears of Northwestern University bioethics professor Laurie Zoloth, this sounds like an old story. "Whenever one hears these things, that there is a conspiracy against patients, if you come to us we will tell you truth, then one has to ask, 'Why are your statements credible?'"

Has anti-aging 'arrived'?
That is precisely the question many consumers are now being asked to answer for themselves. If their M.D. is signing onto anti-aging, does that mean the message is now credible? Does the certificate on his or her wall mean that real anti-aging has, at last, arrived? Or does it simply mean that every patient now has one more reason to live by the Latin phrase caveat emptor - buyer beware?

Dr. Thomas Perls, a Boston University researcher who studies centenarians (people who live at least 100 years), and a vociferous critic of the anti-aging industry, argues that while some anti-aging practitioners "may have their hearts in the right place ... in my mind the whole anti-aging practice has so many problems of ethical and professional misconduct. These practices are selling medicines and substances at great profit with very little in the way of clinical studies to support what they are doing."

The answers to the science questions can be complicated, but the motivations of some doctors to enter the anti-aging world are not. Dr. Arnold Relman, a former editor of The New England Journal of Medicine who is now a professor emeritus of medicine and social medicine at Harvard Medical School, believes "the interest in anti-aging practice is mainly based on economic considerations" by physicians who are looking to boost income.

"Get your piece of the $50 billion anti-aging marketplace!" trumpets a flyer distributed to doctors at XX's Las Vegas meeting. An article by X and X in "Medical Spas," a magazine that's a member of XX, encourages doctors to open their own medical spas and to have them certified under the World Council for Clinical Accreditation, another XXX organization, because "a single anti-aging patient is estimated to bring $4,000 to $20,000 in annual gross revenue."

The business can be very good, indeed. Doctors can count on regular hours because the patients are not sick. Better yet, patients pay cash because visits and procedures are not generally covered by insurance, which also means there is no upper limit to fees. And since there is no need to deal with insurance companies or HMOs, practices do not require extra staff to handle all that paperwork.

Additionally, anti-aging doctors often sell lines of creams and supplements, such as vitamins, antioxidants and plant extracts, which claim to do everything from strengthening the immune system to boosting libido, directly out of their offices, sometimes with an enormous mark-up. They can also use their own in-office technology, like those GE body scanners, to charge for in-house testing.

Patients generally see anti-aging doctors much more often than regular physicians. That's because in addition to checking on measures like weight and body fat and how patients are feeling overall, the docs are constantly monitoring a large range of sometimes esoteric health indicators with a battery of medical tests, including urinalysis and blood work. They look for levels of everything from testosterone and estrogen to follicle stimulating hormone and dehydroepiandrosterone (a natural steroid known as DHEA). Based on all these results, the doctors may then recommend drugs, hormones, supplements and special diets and fitness regimens - and then set an appointment to see the patient again in several weeks or months for another cash-only check-up.

One doctor, two hats
Dr. Andrew Jurow, an ob-gyn in Burlingame, Calif., says he started an anti-aging practice alongside his ongoing traditional practice after becoming a devotee himself. "I am as mainstream as you can get. I am 59 years old, board certified in ob-gyn, as was my father. If you had come to me five, six years ago and talked about anti-aging, I would have said, 'Hogwash!'"

But then Jurow, long an avid exerciser, attended an A4M meeting and came away impressed with what he heard. Five years ago he began visiting an anti-aging doctor himself. Now he sees his regular ob-gyn HMO patients through one door of his building and anti-aging patients through another.

Jurow says he is not getting rich off his anti-aging patients. Rather, his motivation is his own belief that it works. Still, he says, if he sees an anti-aging patient for an hour, he can charge $350, whereas HMOs might reimburse him as little as $50 for a traditional office visit.

Dr. Mickey Barber, a Charleston, S.C., Cenegenics affiliate and Gooden's physician, was an anesthesiologist before turning to "age management" medicine five years ago. She believes that mainstream medicine "at one point in time was lucrative, but it is less so now with health insurance, litigation, and many doctors became discouraged. I think doctors are looking for another way to provide medical care for patients, and if part of that pays the bills, sure."

A typical evaluation of a new patient in Barber's clinic, she says, takes about seven hours and she may order up to 90 laboratory tests. The day costs $3,000.

Johnny Adams, a 58-year-old software consultant in Newport Beach, Calif., has experienced the way some anti-aging doctors bump fees by prescribing and testing. He has spent between $1,400 and $2,000 per year for the last four years on anti-aging, but that represents a big drop in his costs.

When he first began, he says, he tried a number of doctors. "One had me on a very overly aggressive and rather na¯ve program. He had me on everything under the sun. Pretty soon I was taking something like 178 different nutritional supplements, hormones, some prescription drugs I was getting from overseas." Now he focuses on nutrition, exercise and some supplements such as omega-3s, antioxidants and vitamins.

The anti-aging field's emphasis on supplements comes even though there is little evidence that most do anything for people who already eat a healthy diet. "I know it's possible that I'm just giving myself expensive pee," says Snyder, the ER doc, laughing.

Unlike manufacturers of prescription and over-the-counter medications, dietary supplement makers do not have to prove their products are safe or effective before selling them. Some supplements have been shown to be contaminated with lead or other harmful substances. And research has even found that large doses of antioxidants, like beta-carotene, actually increase cancer risks.

Hormones are hot
But hormones are the most popular tools in anti-aging's armory. Scientists recognized their potential over 100 years ago, but their use in modern anti-aging traces back to July 1990 when a researcher named Daniel Rudman published a study about the effects of human growth hormone (HGH) on men over 60 in The New England Journal of Medicine.

Though the anti-aging industry existed long before then, Texas entrepreneur Howard Turney, who now calls himself Lazarus Long after an immortal character in a Robert Heinlein novel, created a new version. He was so enthused about Rudman's positive results that he started a resort called El Dorado in Cancun, Mexico, to administer HGH to those seeking rejuvenation. XX, then an osteopath and a consultant at El Dorado, held the XXX's organizing meeting there.

Rudman issued many caveats and cautions about using HGH and never recommended its use to delay aging. In fact, he was horrified his study was being used to support the industry especially since heavy use of growth hormone can have unwanted side effects. Endocrinologists worry that unnecessarily taking HGH could trigger cancers, diabetes and other hormone-related conditions. There are still many unknowns.

Still, HGH, the body's "master hormone," became the hottest thing to hit anti-aging since vitamin C because it was a real drug that appeared to restore youthful vigor.

**** wrote a 1996 book, "Grow Young with HGH," summing up the life-extension world's hope that there was finally a fountain of youth in a bottle. He dedicated it to Rudman saying, "His vision and pioneering human research with growth hormone for anti-aging marked the beginning of the end of aging."

Now that sports doping scandals have made HGH, as well as testosterone and other hormones, front-page news, and some anti-aging clinics and compounding pharmacies have been raided by the U.S. Drug Enforcement Agency for being overly liberal with hormone prescriptions, the anti-aging community has toned down its endorsement of hormones, at least in public.

"Less than 10 percent of patients involved in anti-aging are receiving growth hormone," Klatz insists.

That seems a dubious assertion. In fact, hormones remain a key ingredient of anti-aging practice. "Most of my anti-aging patients get hormones," typically growth hormone as well as sex hormones appropriate to each gender, Jurow says.

In his own article in "Medical Spas," XX argues that one of the main reasons for an M.D. to partner with a med spa is to "offer patients ... Bio-Identical Hormone Replacement Therapy, which aims to arrest age-related declines in hormone levels such that the natural peaks achieved in youth are maintained throughout life."

Yet there is no evidence that people live longer if they take HGH - lab animals with less growth hormone actually live longer than their normal brethren - or any other hormone. Nor is there any conclusive proof hormones make healthy older people any healthier. Research results are mixed, the picture murky.

The recent death of Cenegenics founder Dr. Alan Mintz, a prime HGH promoter, demonstrates that growth hormone is no panacea. He died last June, at age 69, reportedly during a brain biopsy.

As some enthusiasts admit, anti-aging patients are essentially running a giant uncontrolled experiment on themselves - increasingly at the hands of doctors.

Critics point out that the biggest concern about doctors getting involved is that many patients incorrectly assume that if their trusted physician is recommending hormones and supplements, these treatments must be safe and effective.

The fact is, no drug, treatment or supplement has ever been shown to extend human lifespan.

But Gooden, the Charleston real estate agent, calls her own transformation at the hands of Barber "a miracle."

"For as long as I can remember I have had insomnia," she says. "And increasing pain that doctors said was arthritis." Barber's daylong testing, however, "showed what needed to be dealt with," mainly deficiencies in DHEA, estrogen and testosterone. "My hormonal levels were way out of whack, my cardiac function was not what it should be," Gooden says.

Barber arranged for Gooden to meet with a personal trainer and a nutritionist and prescribed a host of prescription drugs such as testosterone, estrogen and thyroid medication, and the usual array of anti-aging supplements like DHEA and vitamins, most of which she obtains from Barber.

These days, many anti-aging promoters, seeking to shed the flim-flam image, are ratcheting down the rhetoric. They have begun using terms like "age management" and "healthy aging" that imply realistic goals and give important, if commonsense, advice.

Most anti-aging doctors tell patients what we already know: Exercise. Lose weight. Lower our blood pressure. Don't smoke. "I do not see this as the basis for a new practice specialty," argues Relman, the professor emeritus at Harvard.

But a good anti-aging doctor, says Snyder, is more like a devoted personal mountain guide. Rather than cramming sick patients into quickie appointments, he or she will "push you into exercise, get you to join a club, get a personal trainer, a nutritionist to create a full diet to follow and not just for weight loss. They'll direct you to certain supplements, antioxidants, watch the glucose curve to see if you are borderline diabetic. If you go to a regular doctor he will not be as proactive. He'll wait for an event to happen, then treat it. That is what I do in ER medicine."

That kind of preventive care is what Orange County, Calif., entrepreneur and long-time anti-aging advocate David Kekich, 65, says he gets from his anti-aging doctor. Though he did try testosterone therapy for a short time, he was unable to continue because it aggravated pain from a spinal cord injury. Instead, Kekich and his physician have built a program of rigorous exercise; a low-fat diet with abundant fresh fruits and vegetables, little red meat and no sugar or processed flour; regular blood testing; and aggressive supplementation - up to 60 tablets per day.

"I see my doctor about once a year," Kekich reports. "He fine-tunes things. Regular doctors could not even come close. When I have gone to them they tell me I am crazy and should not even look at these things and that I should wait until I have a problem. But to me that is closing the barn door after the horse is gone. Most doctors are mechanics. They fix things. To me, prevention is the name of the game."

Filling a gap
Mainstream medicine may look askance at anti-aging practices, but it has adopted its elements. Sterling centers such as Princeton, Stanford, the Cleveland Clinic, Northwestern University, Duke University and others have established "executive health" programs where the wealthy undergo similar day-long evaluations, and testing costing thousands of dollars.

The fact that the wealthy are willing to pay so much, and that doctors are catering to them, is more a comment on the health care system we have built, says Northwestern's Zoloth, than on the validity of anti-aging medicine.

Relman agrees that anti-aging medicine is stepping into the growing gap between the public and faith in the health care system. "It is unfortunate but understandable given the sad facts about the current state of medical care in this country," he says. "Without a strong base of primary care, you cannot have an effective health care system. It breaks down into specialized and unconnected procedures and tests and gets more and more disorganized and unsatisfactory, and that is what is happening in America today."

Though it may fill the gap, much of the anti-aging agenda is still based more on hope than evidence. "We do worry that there could be bad effects 20 or 30 years from now," admits Jurow, referring mainly to hormones.

In the world of anti-aging, though, which sees us all moving closer to death with every passing minute, hope outweighs proof. "We don't have time to wait half a century to find out if something is really going to work!" XX says.

Brian Alexander, a frequent contributor to msnbc.com, is the author of "Rapture: A Raucous Tour of Cloning, Transhumanism, and the New Era of Immortality" and "America Unzipped: In Search of Sex and Satisfaction."