For years, medical textbooks have been repeating pretty much the same thing about our intestinal gas. What if these numbers were completely off the mark? At the University of Maryland, researchers have developed smart underwear capable of recording each puff of gas, in a real situation, without going through probes or embarrassing examinations.
Their idea: clip a small sensor to the edge of the underwear to continuously monitor the hydrogen present in flatulence, a gas produced only by the intestinal microbiota. Until now, estimates were based mainly on approximate memories, around 10 to 20 farts per day. The new measures tell a different story.
Smart underwear that doubles the average number of flatulences
In a first study, 19 adults wore the device for seven days, an average of 11 hours per day. Result: the sensors detected on average 32 episodes of flatulence per daymore than double the 14 events often cited in the medical literature. Depending on the individual, the count ranged from 4 to 59 daily farts.
This difference does not surprise intestinal gas specialists. In 2000, gastroenterologist Michael Levitt wrote: “It is virtually impossible for the physician to objectively document the existence of excessive gas using currently available tests.”. Why were previous estimates so low? Older studies used intrusive rectal probes or diaries where patients forgot farts, especially at night.
Smart Underwear: how this sensor tracks flatulence on a daily basis
The device, called Smart Underwearis a small box of about a centimeter that clips to the outside of any underwear, near the perineum. Inside, an electrochemical sensor measures the hydrogen contained in each fart and records the time of passage. For the majority of people, flatulence consists mainly of hydrogen, carbon dioxide and nitrogen. In some individuals, methane may also be present. Hydrogen, produced only by intestinal microbes, allows, through continuous monitoring of its concentration in flatulence, to directly evaluate the food fermentation activity by the intestinal microbiota, particularly with regard to timing and intensity.
© Brantley Hall, University of Maryland.
“Think of it like a continuous glucose monitor, but for intestinal gas” summarized Brantley Hall, assistant professor in the Department of Cell Biology and Molecular Genetics at the University of Maryland.
In the feasibility study, the 19 volunteers wore the sensor an average of 11.3 hours per day for a week, without keeping it in the shower, on the toilet or during strenuous sport. Nearly 95% found it comfortable. As night wear was optional, these 32 farts a day
correspond rather to a minimum than to a maximum.
Atlas of Human Flatulence: what our farts reveal about the microbiota
To verify that the sensor accurately reflects the activity of the intestinal microbiota, the team conducted the GUMDROP trial on 38 people. Two days of a very low fiber diet, then one day with sugar candies, and another with candies containing inulin, a prebiotic fiber. Smart Underwear detected the increase in hydrogen linked to inulin in 36 out of 38 participants, a sensitivity of 94.7%.
Next step: the Human Flatus Atlasa large study where hundreds of adults will wear these smart underwear day and night. “We don’t actually know what normal flatulence production looks like,” Brantley Hall acknowledges.Without this reference, it is difficult to know when someone’s gas production is truly excessive.”. Volunteers will be classified:
- “Zen digesters”: these are individuals who, although they consume a diet rich in fiber (between 25 and 38 grams per day), produce very little gas. They could provide us with valuable information on how the intestinal microbiota adapts to such a diet;
- Hydrogen hyperproducers: This term refers to people who emit a significant amount of flatulence. The analysis of these cases could help to understand the reasons for this increased gas production;
- Normal people : those which fall between the two groups previously mentioned.
© Brantley Hall, University of Maryland.
To study the microbial factors behind gas production in the two extreme cases, the team will collect stool samples from the first two groups for microbiome analysis. “We have learned a lot about the microbes that live in the gut, but less about their activities at any given time.”said Brantley Hall. “The Human Flatulence Atlas will establish objective baseline data for intestinal microbial fermentation, providing an essential basis for assessing the impact of dietary, probiotic or prebiotic interventions on microbiome activity.”.