What a Gas

There are worse places to be than Dr. Michael Levitt’s waiting room. Chernobyl, for instance. Or Love Canal.  It’s not that there’s anything wrong with Levitt’s facilities themselves, you understand. Indeed, as doctor’s offices go, they’re better than most. There are no millennia-old copies of Travel & Leisure on the coffee table (A Weekend in Pangaea!), no sour balls from the mid-1950s in the receptionist’s candy dish, no relentless Muzak repetitions of The Girl From Ipanema. No, the problem with Dr. Levitt’s waiting room is Dr. Levitt’s patients.  Michael Levitt is a gastroen-terologist working at the Veterans Affairs Medical Center in Minneapolis. The term gastroenterology, of course, refers to the branch of medicine that treats ailments of the stomach and bowels and comes from the Greek gaster, for belly, and enterology, for someone who really ought to wash his hands before making you a sandwich. For a medical specialty high in heroism and low in glamour, you can’t do much better than gastroenterology, but in Levitt’s practice the stakes have been raised. For the past 15 years, Levitt has been roundly recognized as one of the world’s leading authorities on the science of flatulence.  Flatulence is the means by which the body rids the colon of unwanted gases, the intestines of unwanted pressure, and crowded theater rows of unwanted strangers. Its familiarity notwithstanding, it has generally ranked near the bottom of most people’s lists of Impressive Things the Body Can Do--just a notch above the ability to flatten Coors cans against our foreheads. Despite the low esteem in which nature’s joy buzzer has been held, however, a handful of researchers have made it the chief object of their study. What, they have asked themselves, can it tell us about the functioning of the body? How, they have challenged one another, can it be alleviated when it becomes excessive? Why, their families have asked them, couldn’t they at least have considered a nice podiatry practice? Levitt is one of the rare scientists who have been willing to tackle these questions, and after 19 years in the flatus game, he does not regret his choice.  An enormous amount of lore has grown up around the phenomenon of flatulence, he says, much of it untrue. Debunking these myths and uncovering the truth is like investigating any poorly understood area of medicine. The answers are all there--if you’re willing to go after them.  Levitt came by his interest in eruptive science in a somewhat dramatic way. In 1976 a patient approached him with what Levitt later decorously described in a New England Journal of Medicine paper as a five- year history of passing excessive flatus. The demure phrasing in Levitt’s writing did nothing to capture the problems his patient faced. Since 1971, the prudently unnamed 28-year-old male confessed, he had been passing intestinal gas far more than he ever had before in his life, and certainly more than any of his understandably put-upon friends and family members. For the previous two years, he had been keeping a scrupulous record of his personal greenhouse emissions, and when he revealed these so-called flatugraphic recordings to Levitt, the doctor was taken aback. On an average day the patient recorded 34 episodes of flatulence, with some days cresting into the low 40s. Levitt did not have any data on how this compared with the output of the ordinary person, but even in a globally warmed, ozone-shredded, chlorofluorocarboned world, this sounded bad. Before his unhappy patient detonated at a mooring mast in Lakehurst, New Jersey, Levitt decided to take his case.  In treating a man complaining of flatulence, there are many things a doctor must consider--not the least being that the patient is a man. From toddlerhood to dotage, there are few skills more highly prized by the average male than a facility with flatulence. Why men should seem more open about their gastric volatility than women is a mystery, but from a sex whose inventiveness gave the world the noogie and the wedgie, a fascination with all things intestinal should not come as a surprise. While most men do what they can to curb this natural impulse, limiting themselves to such flatus surrogates as whoopee cushions and fireworks, an affinity for flatulence remains.  To study a problem of extraordinary flatus, Levitt needed data on what ordinary flatus is. Recruiting seven highly cooperative volunteers, he requested that they spend at least a week keeping flatugraphic logs of their own, recording how frequently they stirred intestinally and when these events occurred. While taking the time to note such events would not make for an especially social week, it would make for a scientifically enlightening one, providing Levitt with what was almost certainly science’s first flatulence control group. When the results were in, it was clear that control was just what his seven volunteers did have and what his troubled patient didn’t.  In the group I chose, Levitt says, the mean flatus frequency turned out to be 13.6 episodes per day, with no statistically significant differences attributable to age, gender, or other discernible variables. The upper limit for even the most gaseous of these subjects was less than 20. In all cases the daily output was considerably lower than my patient’s 34, indicating that his problem was quite real.  More disturbing than the frequency of flatus from the afflicted man was the quantity of effluence produced by each event. It’s well known that a flatulent episode can range from a barely detectable rumble to a propulsive burst sufficient to attain low Earth orbit, depending on general health and recent visits to all-you-can-eat salad bars. With the help of internally worn rectal tubes and 100-milliliter collection syringes, an earlier study had determined just what the standard output of all these eruptions is.  The average person appears to release between 500 and 2,000 milliliters of gas per day rectally, Levitt says, with the average volume of what passes at once varying between 35 and 90 milliliters. The young man I was treating released an average of 5,520 milliliters per day, or 162 milliliters per event.  By any measure, it was clear that Levitt had discovered the Joltin’ Joe of digestive distress, but before consigning the unfortunate man to a private wing in gastroenterology’s Hall of Fame, Levitt knew he’d have to investigate further. The next step, he decided, was to study not just the quantity of the patient’s gaseous output but its makeup. Given the power of intestinal exhaust to turn heads, clear rooms, and in extreme cases fell whole swaths of old-growth forest in the Pacific Northwest, this least fragrant vapor would seem to be made of only the most pungent stuff. Yet according to analyses Levitt--and later others--conducted on captured flatulence, intestinal gas can be surprisingly benign.  When you analyze rectal gas, Levitt says, you find that it is about 99 percent carbon dioxide, hydrogen, nitrogen, oxygen, and methane. Most of these gases are either swallowed inadvertently when food is eaten or released from the food as it is digested. What makes this remarkable to most people is not just that these gases are so common but that they are also utterly odorless.  For flatus to attain its singular bouquet, it must rely on the remaining 1 percent of the gas that makes it up--a percent composed of very different stuff, which comes from a very different source. Like all complex organisms, the human body is home to millions of microorganisms that live in our hair, pores, and even our internal organs. The part of the body that is apparently zoned for the most residential development--at least by house-hunting one-celled organisms without much of an eye for resale values--is the digestive tract. Among the better known microbes that receive their E-mail and E! channel in your intestines is the prolific E. coli. Among the lesser known are Klebsiella and Clostridium. All these organisms live for the most part in the colon, where they attack and consume undigested food and in turn generate their own waste products. In the case of microorganisms, waste usually means gas, and in the case of these microorganisms, that gas can be pretty ripe stuff--usually molecules containing sulfur, such as dimethyl sulfide and methanethiol. When these waste products build up to a sufficient level, they are released with the rest of the gas in the bowels, announcing their presence--and too often yours--to the world.  The odoriferous gases present in flatus are present in extremely small concentrations, Levitt says. It is a testament both to the pungency of the gases and to the sensitivity of the nose that we can detect them so readily.  Of course, not all episodes of flatulence carry an olfactory price tag. Some people, it seems, can release all the intestinal gas they want with no one the wiser, while other people seem to be unable to enter a room without first having to file an environmental impact statement. While it’s tempting to conclude that individual quirks of individual metabolisms account for these differences, the answer usually has less to do with our bodies than with what we put into them--particularly when what we put into them are carbohydrates.  Nutritionists have long known that while there are many kinds of carbohydrates present in food, Levitt says, not all of them are digestible. Generally it is only the simplest carbohydrates, made up of the simplest sugars, that we’re able to process. Some complex carbohydrates-- those made up of three or four sugar molecules--can’t be broken down by normal metabolism. When these get into the digestive tract, they are simply passed along to the colon, where the intestinal flora get hold of them.  Among the foods with the fewest complex carbohydrates and thus the fewest flatulent consequences are meat, fish, grapes, berries, potato chips, nuts, and eggs--the so-called normoflatugenic foods. Further up the gaseousness scale are pastries, potatoes, citrus fruits, apples, and breads, all of which contain some complex sugars, and thus some potential for flatulent fallout. At the top of the explosiveness list are the Fat Man and Little Boy of our diets--those foods that are practically nothing but complex sugars. Among these most eruptive edibles are beans, carrots, raisins, bananas, onions, milk, and milk products.  When Levitt began treating his grievously gassy patient, it was these well-nigh radioactive consumables that first drew his attention. In his initial journal paper, as well as in a subsequent paper entitled Follow-up of a Flatulent Patient (itself later followed up by Flatulent Patient: The Musical!), Levitt described the painstaking process by which the patient altered his diet to determine which foods were responsible for his distress. During the first three weeks of the patient’s treatment regimen, Levitt restricted him to the normoflatugenic foods and got immediate results: the incidence of flatus fell from 34 bursts per day to fewer than 17--well within the normal range. After this trial period, Levitt and his patient tested the possibility that the young man’s gas- producing proclivity had diminished by adding a full quart of milk to his diet.  While residents of Minneapolis do not refer to The Day Michael Levitt Gave His Flatulent Patient Milk with the same post-traumatic numbness exhibited by, say, survivors of Mount Pinatubo, the event could not have gone wholly unnoticed. In the 24 hours that followed the milk ingestion, the patient reached something close to critical gaseous mass, recording fully 90 episodes of flatus in his flatugraphic diary, including one especially productive three-hour period in which he experienced nearly 60 intestinal utterances. The cause and effect between input and output was so immediate and so direct that Levitt knew he had found his smoking, uh, gun.  It turned out, he says, that this patient was lactose intolerant. Lacking the enzyme to digest the carbohydrates in milk, he simply passed them on to his colon, where the bacteria digested them for him. In many lactose-intolerant patients, milk ingestion can lead to gas. In this patient the intolerance was severe, so the gas problem was, too.  The solution to the patient’s gaseousness was simple, involving nothing more than maintaining the low-flatulence diet, and on those occasions when milk was ingested, consuming it only with an accompanying dose of lactase, an enzyme that aids in milk metabolism. In the years since, Levitt has lost contact with the now middle-aged man, and with the exception of a few false alarms--California’s 1994 Northridge quake, for example--all has been quiet on at least that flatulence front. But even though his patient’s mystery has been solved, Levitt himself has hardly been lying down on the job, using the last two decades to expand science’s flatus horizons even further.  Among the greatest challenges he and the rest of medicine’s flatulence strike force now face is determining whether there is a way to curb intestinal gas without appreciably restricting a patient’s diet. The solution may well involve enlisting the aid of some of the very microorganisms that stir things up in the first place. The Methanobacterium smithii bacterium, Levitt has learned, is a bit of a microbial specialist, producing not the whole range of gases that make up flatulence but just methane, a gas molecule made up of four hydrogen atoms and one carbon atom. As M. smithii manufactures its gas of choice, it reduces the overall volume of gas surrounding it by condensing four stray molecules of hydrogen and one of carbon dioxide into a single molecule of methane and two waters (which are absorbed by the colon), thus lowering the pressure in the bowels in the process. The problem, as Levitt has learned, is that M. smithii is one of the least common of all bowel bacteria, far outnumbered by E. coli and its less fragrant ilk. Short of running a less than appealing classified ad (HELP WANTED: Methane Manufacturer; Must Be Willing to Work Indoors), there does not seem to be any way to increase the population of the desired microbe.  It’s only in recent years that we’ve identified all the bacteria in the intestines, Levitt says. It will be a while before we can effectively manipulate them.  On other fronts Levitt has had greater success, most recently developing a simple Breathalyzer test that can check a patient for incipient flatulence. To the average nongastroenterologist this seems a bit counterintuitive, and if Levitt is checking his patients’ breath for flatulence, I wouldn’t even ask how he’d propose to conduct dental work. Levitt, however, insists his system works, explaining that what goes on at one end of the alimentary autobahn can often reveal a lot about what’s happening at the other.  Flatulence is characterized by an overproduction of a wide range of gases, including hydrogen, he says. Not all of the gas generated in the intestines is excreted, however; some of it is absorbed by the blood and exhaled through the lungs. If you can measure the level of excess hydrogen in a patient’s breath, therefore, you can diagnose a flatulence problem and perhaps help reverse it.  In a world that has long lionized doctors, Levitt knows that he will forever labor in something close to obscurity. There will be no prime- time programs dramatizing flatulence work (St. Anywhere Elsewhere), no CNN panel shows debating it (Crossfire!), no PBS specials helping raise money for it (All Creatures Great and Small--But Some From a Distance). Nevertheless, Levitt remains committed to his discipline of choice, and well he might. It was no less a physician than Hippocrates who coined the admonition First, do no harm. Levitt can take some satisfaction in knowing that his medical specialty is the only one in which this rule applies as much to the patient as it does to the doctor.