Listen to Dr. Robert Charm behold the beauty in a cleansed colon: "We're all toxic dumpsites," he says. "It comes from not getting properly rid of the things we eat. Colon hydrotherapy is a body clean-out. It's more aesthetic than a bowel movement. A bowel movement is not a thing of beauty. But a colonic can be."

Charm is a gastroenterologist, professor of medicine at the University of California and amiable oddball who calls himself -- sans any trace of irony -- America's No. 2 Doctor, the King of the Colon and the Prince of Poop. He spells out his last name as an acronym for his personal mantra: Choosing Health And Realizing Miracles. And he believes in the miracle of colonics.

You've seen the ads in the back pages of certain health magazines, in "personal services" sections of alternative newspapers and on bulletin boards at organic food stores: colon hydrotherapy, colonic irrigation, get your colonic here. It's the naturopathic procedure that calls for gallons of water to be pumped through your large intestine to wash out any lurking toxic sludge.

In recent years, getting a colonic has become the celebrity health fad du jour. Princess Diana was an outspoken fan -- British newspapers reported that she spent $4,300 a year grooming her colon -- and just a few weeks ago Damon Wayans was chatting up the procedure on Howard Stern's radio show. The name itself has the ring of the high life -- it sounds like the trendy cocktail you'd overhear a celebrity ordering at some Hollywood bar-to-the-stars: "I'll have a gin-and-colonic, Rudy, extra lime."

Maybe you've wondered about the procedure. How does it work? Is it good for your health? Or is it, in fact, bad for you? Is it dangerous? It depends on whom you ask.

"It's extremely beneficial," says A.R. Hoenninger, a naturopathic doctor and executive director of the International Association for Colon Hydrotherapy in San Antonio.

"It's insane," says Dr. Stephen Barrett, a retired psychiatrist and investigative reporter who runs the nonprofit watchdog agency QuackWatch.

The battle lines over colonic irrigation have been drawn, and they run along the five feet of stretchy tube that is the human colon. In our modern etiquette, the organs of digestion and elimination are typically regarded as filthy, embarrassing and not fit for discussion in polite company, like some secret stash of explicit unmentionables you keep squirreled away in the dark confines of your abdomen. Nobody likes talking about bowel function -- nobody, that is, except 7-year-old boys and gastroenterologists -- so let's get it over with as succinctly as possible.

The colon is the end part of the twisty, turny, tubular hose that makes up the human gastrointestinal tract. After you eat, and after all the food's nutrients have been absorbed in the small intestine, the colon is the last stop on your dinner's GI tour, the place where excess liquid is absorbed and friendly acid-forming bacteria break down what's left of the undigested food. As this is happening, waves of intestinal muscle contractions -- called peristalsis -- urge the remains through your colon and onward to the exit door for, you know, elimination.

Unfortunately, the story doesn't always have such a happy ending. Because the typical American diet is so sadly low in fiber and so astronomically high in processed foods, fatty meat, refined sugar and various preservatives and toxins, and because that stuff's so difficult to digest, not all of it makes a trouble-free exit from your body.

You know what happens. You get constipated, bloated. Your stomach hurts, you get cramps. Then what? You can help yourself to the drugstore's towering stockpile of remedies -- laxatives, diuretics, the various suppositories, enemas and cathartics. Or you could get yourself a colonic.

Naturopathic doctors like to declare that "death begins in the colon." What they mean is that all the Big Macs, Ding Dongs, corn dogs and Cheez Whiz you've ever eaten have left remnants in your colon that loiter there to this day, emitting toxins into your body's bloodstream that will, eventually, inevitably, poison the bejesus out of you. Autointoxication, the process is called.

One colon hydrotherapy Web site estimates that some people are carrying around "10 to 25 pounds of dried fecal matter in their colon" and blames this toxic condition for a litany of maladies, including "constipation, diarrhea, frequent headaches, backaches, fatigue, bad breathe, body odor, irritability, confusion, skin problems, abdominal gas and bloating, lower back pain, sciatic pain, low resistance to colds and infections, low energy and vitality." Writing about the clinical applications of colonics, Dr. Donald J. Mantell says, "Almost every human ailment has been attributed to a malfunctioning colon."

The urge to purge is nothing new. The Greek historian Herodotus, commenting in 440 B.C. on the health habits of his contemporaries, wrote, "For three consecutive days in every month they purge themselves, pursuing after health by means of emetics and drenches; for they think that it is from the food they eat that all sicknesses come to men."

The 19th century Russian biologist Elie Metchnikoff accused the colon of being "the body's greatest enemy." In the early 1900s, thousands of Americans suffering from various strains of GI distress streamed to Dr. John H. Kellogg's sanitarium in Battle Creek, Mich., to have their bowels peeped into, pumped and purged. Kellogg, the cornflake pioneer, a man maniacally obsessed with the functions and malfunctions of human digestion, employed a hodgepodge of bizarre procedures -- including colonic irrigation -- to temper his patients' unruly bowels.

The popularity of colonics peaked early in the century, then dropped off during ensuing decades. Then, within the last few years, as the interest in alternative medicine and naturopathic health care has grown and as the modern fixation with bowel function continued to thrive, more people started going in for colonics.

The procedure itself is carried out with prim efficiency, usually by a colon hydrotherapist or chiropractor. During your colonic, you lie on an inclined table with a sort of built-in potty at the base, a towel covering your privates. A plastic hose is connected to the irrigation machine on one end, and the other end goes into you via a speculum inserted in the rectum. A hydrotherapist oversees the entire procedure, adjusting the volume and temperature of the water, pumping it into you under gentle pressure and lightly massaging your abdomen to work the water through the colon. During several fills and releases, 20 to 30 gallons of water -- or upwards of 40 gallons for a "high colonic" -- are pumped in and sluiced out through an evacuation hose, washing impacted waste from the colon walls, leaving your internal plumbing squeaky clean.

The health payoff, according to promoters, is a strengthening of muscles in the digestive tract, restored pH balance, a feeling of heightened energy, a stimulated immune system, an overall boost in health and vitality and -- of course -- stupendous regularity.

Take A.R. Hoenninger, for example. Back when he was an Air Force pilot, often trapped in the cockpit for hours without relief, "I had trained my bowels not to go on command," he says. "I had terrible constipation problems." When he retired from the Air Force he underwent a series of colonics and "it was extremely beneficial." Now, tanned, rested and regular, he gets a colonic once a month.

But opposing doctors say that colonic irrigation is worse than useless. "It has no value," Barrett says, "and it can be harmful in several ways." According to Barrett, colonic equipment, if not properly sterilized, can trigger serious infections. Also, the wear and tear of repeated irrigation, he says, can foul up normal bowel function by destroying the reflexes that tell you when nature's calling. Electrolyte imbalance can cause the chemicals in the blood to change composition, and excessive fluid absorption can, in some cases, trigger heart failure.

Hoenninger says you just have to be careful. To avoid infection, "You want to go to a place that uses disposable speculums. If they're not disposable, they should be cleaned in an autoclave. As long as the equipment is FDA-registered, and the hydrotherapists are licensed, it's safe for most individuals." And the health benefits? "It aids with constipation; it's beneficial pre- and post-operative for any surgical procedure." Hoenninger allows that certain people -- pregnant women and folks with high blood pressure -- should avoid the procedure.

Barrett thinks everyone should avoid it. He says the very notion of autointoxication is a bunch of Old World hoo-ha. "It comes from a time and mentality that says stagnation in the colon is the root of all disease. The idea that old waste stagnating in the colon produces toxins that poison the body -- it simply doesn't occur. Observation of the colon in surgery has shown that no feces accumulates on the walls of the colon."

Oh yeah? "He's obviously never done a colonoscopy," says Charm, speaking from his office between patient visits. "Fifty percent of people over 50 have diverticulosis" -- a condition that causes small sac-like pockets to form in the colon wall -- "and a third of those have retained feces in the colon. I do colonoscopies every day, there's a tremendous retention of particles. I just saw a 37-year-old patient loaded with it."

Doctors plainly disagree on the value of colonics, and the American Gastroenterological Association refuses to weigh in with a judgment call. "We have no position on colonic irrigation," says Carole Anikis of the AGA News Bureau. Anikis has called some of the 10,000 AGA members to get their take on colonics. Across the board they've said, "They don't do it, don't know anything about it, can't comment on it." (Although, she confides, "One doctor said it's B.S.")

Here's one point about colonics that everyone agrees on: The procedure has never been tested or analyzed as a means of legitimate health care. "No one has done the slightest kind of clinical study," Barrett says. "How can you pretend there's a health benefit? Where has it been published?" When asked to point to peer-reviewed medical literature that documents the benefits of colonics, Hoenninger admits, "There's almost none. There absolutely is no data."

There is, however, plenty of literature that pooh-poohs the procedure. The National Council Against Health Fraud, a nonprofit agency that targets health misinformation, issued a 1995 position paper on colonic irrigation saying, "Colonics have no real health benefits, but do have a number of serious hazards. Consumers should not use colonics, and should avoid patronizing practitioners who employ this procedure. Practitioners who use colonics are either too ignorant or misguided to be entrusted with delivering health services." In 1985, the infectious disease branch of the California Department of Health Services stated that "neither physicians nor chiropractors should be performing colonic irrigations. We are not aware of any scientifically proven health benefit of this procedure, yet we are well aware of its hazards."

So are they reckless -- the doctors who go on condoning colonics? "They're delusional," Barrett says. "They have false, fixed ideas." Are there any health benefits at all from getting a colonic? "No. You stand to lose money, time and the reflex that allows you to have bowel movements."

Hoenninger, of course, takes a brighter view: "Every time I have a session I feel much, much better."

Does death begin in the colon, or does death begin with colonics? The Barretts and Hoenningers of the world will never agree on that age-old question. Finally, in the most basic terms, they view the human colon from opposite ends of the argument.

The ever-charming Charm takes a more moderate stance. "Those toxins are sitting there in your colon. Colon hydrotherapy is a way to clean it out. I'm annoyed that I waited so long to learn about it. I'm 69 years old. I want to be the oldest living doctor in America."

You go, Dr. Charm.