“Even now,” he says of his flatus work, “it overshadows everything else I do.” Levitt and I are sitting in a conference room upstairs from his lab at the Minneapolis VA Medical Center. Levitt has a goofy, lopsided smile and a pale complexion. I couldn’t recall, while writing this, whether his hair was gray, so I typed his identifiers into Google Images. A photograph of a can of baked beans came up.
For the record, here are some of Michael Levitt’s other contributions to medicine: He invented the breath hydrogen test, which originated not as a flatulence assessment technique but to diagnose malabsorption of carbohydrates in the small intestine. He debunked a diet fad for foods made with “nonabsorbable” carbohydrates. He showed that the wriggling movements of the villi are the key to intestinal stirring and to healthy absorption of nutrients. “I wrote the book on intestinal stirring.”
After what I judge to be a sufficient number of follow-up questions on intestinal stirring, I ask whether it might be possible to see the Mylar pantaloons.
Levitt designed the garment for a pair of studies that aimed both to identify the gases responsible for noxious flatus and to test devices claiming to adsorb—the formal term for binding to something’s surface—those gases. He doesn’t know where they are stored, but digs out a photograph of a woman standing in the lab, modeling them. Shown uninflated, they fit more snugly than I’d pictured them. The material is silver, crinkly, and reflective. They’re the sort of clothes baked potatoes wear.
I ask Levitt whether it was difficult to recruit volunteers for the flatus studies. It wasn’t, partly because the subjects were paid for their contributions. People who sell their flatus are more or less the same crowd who turn up to sell their blood.
“What was hard,” Levitt says, “was finding the judges.” Levitt needed a pair of odor judges to take “several sniffs” and rate the noxiousness—from “no odor” to “very offensive”—of each of the sixteen people’s flatal contributions.* The hypothesis was that noxiousness would correlate with the combined concentrations of the three sulfur gases. And it did.
Curious as to which olfactory notes the different sulfur gases contributed to the overall bouquet of flatus, Levitt purchased samples of the three gases from a chemical supply house. The judges agreed on the following descriptors: “rotten eggs” for hydrogen sulfide, the gas with the strongest correlation to stink; “decomposing vegetables” for methanethiol; and “sweet” for dimethyl sulfide. Though lesser players like methylmercaptan contribute as well, it is for the most part these three notes, in subtly shifting combinations and percentages, that create the infinite olfactory variety of human flatus. To quote Alan Kligerman, “A gas smell is as characteristic of a person as a fingerprint is.” But harder to dust for.