‘Smart Underwear’ sheds new light on just how often humans pass gas

Scientists at the University of Maryland have taken on a problem most people laugh about and doctors struggle to measure. Their solution is Smart Underwear, a small wearable device that tracks intestinal gas in daily life. By focusing on hydrogen in flatus, the team is rewriting what scientists know about how often people actually pass gas and what it says about the gut.

For years, doctors have relied on guesswork. In 2000, gastroenterologist Michael Levitt summed up the challenge, writing, “It is virtually impossible for the physician to objectively document the existence of excessive gas using currently available tests.” Most earlier estimates depended on self reports or short lab tests. Both miss events and fail during sleep.

That gap pushed assistant professor Brantley Hall and his colleagues to try something different. Their device clips discreetly to the outside of underwear and works around the clock. “Objective measurement gives us an opportunity to increase scientific rigor in an area that's been difficult to study,” Hall said.

The first study, published in the journal Biosensors and Bioelectronics, was led by assistant research scientist Santiago Botasini. Nineteen healthy adults wore the device for a week. The results surprised even the researchers.

On average, participants passed gas 32 times a day. That is about double the 14 daily events often cited in medical books. Some people logged as few as four events in a day. Others reached 59. The spread was wide and far larger than older studies suggested.

The reason for the jump is simple. Self reporting misses things. People forget. They sleep. Some barely notice gas at all. Others feel every bubble. Two people can produce the same amount yet describe very different experiences.

Smart Underwear focuses on hydrogen because it comes only from gut microbes. When bacteria break down food the body cannot digest, they release hydrogen. Tracking that gas offers a direct signal of microbial activity. “Think of it like a continuous glucose monitor, but for intestinal gas,” Hall said.

Most people think of gas as an awkward side effect. In this work, it becomes data. Gut microbes work on a fast schedule. Their activity can spike or fall within hours after a meal. Standard tools struggle to capture that timing.

Breath tests measure hydrogen, but levels are low and tests are brief. Stool and blood samples depend on when someone goes to the bathroom or visits a clinic. Imaging gives only snapshots. Questionnaires rely on memory.

Flatus offers a clearer signal. Hydrogen levels in gas can be hundreds of thousands of parts per million, far higher than in breath. That makes continuous detection easier and more reliable.

The Maryland team designed the device to be practical. It snaps onto underwear fabric without piercing it. Coin cell batteries allow about a week of use. Sensors sleep most of the time to save power and wake when gas levels rise.

When the sensor detects a burst of hydrogen, the system logs the timing and strength of the event. Over time, those bursts build a picture of how active the gut microbes are through the day.

To show the device could track real changes, the researchers ran a second study called GUMDROP. Thirty eight adults followed a low fiber diet and wore the device on two test days.

On one day, they ate regular gumdrops. On the other, they ate gumdrops containing inulin, a fiber humans cannot digest. Inulin reaches the colon intact and feeds microbes.

The results were clear. Smart Underwear detected higher microbial activity on the inulin day in 36 of 38 participants, a 94.7 percent success rate. Activity rose about three to four hours after eating, showing the slow pace of fermentation.

Interestingly, about one third of participants reported symptoms after the regular gumdrops, not the fiber ones. That mismatch suggests feelings do not always reflect what microbes are doing.

Unlike blood sugar or cholesterol, flatulence has no accepted normal range. Hall’s group wants to change that with a project called the Human Flatus Atlas.

The idea is to measure gas patterns in hundreds of adults across the United States. Participants receive devices by mail and wear them at home. The team then links gas patterns with diet and stool based microbiome data.

Early results point to three broad groups. Some people eat high fiber diets and produce little gas. The team calls them Zen Digesters. Others produce large amounts and are dubbed Hydrogen Hyperproducers. Many fall in between.

“We've learned a tremendous amount about which microbes live in the gut, but less about what they're actually doing at any given moment,” Hall said. “The Human Flatus Atlas will establish objective baselines for gut microbial fermentation.”

This work could reshape how doctors and researchers think about digestion. Objective gas tracking may help explain why some diets cause trouble for some people but not others. It could guide personalized nutrition, probiotic testing, and studies of digestive disorders.

By measuring microbial activity in real time, scientists can see how meals, fiber, or new therapies change the gut through the day. For patients who feel dismissed when tests come back normal, hard data may offer clarity.

Most of all, the research treats a common human experience with scientific care. Gas is no longer just a joke. It is a signal, and now there is a way to read it.

Research findings are available online in the journal Biosensors and Bioelectronics.

The original story "'Smart Underwear' sheds new light on just how often humans pass gas" is published in The Brighter Side of News.

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